THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 


PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


A 

COMPENDIUM 


OF.  THE 


COURSE  OF  CHEMICAL  INSTRUCTION 

IX  THE 

MEDICAL  DEPARTMENT 

OF  THE 

UNIVERSITY    OF    PENNSYLVANIA. 

BY 

ROBERT    HARE,    M.D. 

PROFESSOR  OF  CHEMISTRY. 

IN   TWO   PARTS. 


PART  I. 

COMPRISING    THE 


CHEMISTRY  OF  HEAT  AND  LIGHT,  AND  THAT  OF  INORGANIC 
SUBSTANCES,  USUALLY  CALLED  INORGANIC  CHEMISTRY. 


'  FOURTH  EDITION. 

WITH    AMENDMENTS    AND    ADDITIONS. 


PHILADELPHIA: 

J.  G.  AUNER,  No.  343  MARKET  STREET. 

John  C.  Clark,  Printer. 

1840. 


I  £40 


PREFACE 

TO  THE  FIRST  EDITION. 


WHERE  a  subject  cannot  be  followed  by  a  reader  without  study,  it 
would  seem  unreasonable  to  expect  that,  without  some  assistance,  it  should 
be  followed  at  a  lecture.  Under  this  impression,  from  the  time  that  I 
became  a  lecturer,  I  applied  myself  so  to  improve  and  multiply  the  means 
and  methods  of  experimental  illustration,  as  to  render  manipulation  easier, 
and  the  result  more  interesting  and  instructive. 

But  notwithstanding  all  my  efforts,  there  remained  obstacles  to  be  sur- 
mounted. However  striking  might  be  the  experimental  illustration  of  a 
property  or  principle,  the  rationale  might  be  incomprehensible  to  a  majority 
of  my  class,  unless  an  opportunity  for  studying  it  were  afforded  them. 

Again,  some  of  my  contrivances,  which  greatly  facilitated  my  experi- 
ments, were  too  complex  to  be  understood  without  a  minuteness  of  expla- 
nation, which,  even  if  it  were  useful  and  agreeable  to  some  of  my  hearers, 
might  be  useless  and  irksome  to  others ;  and  to  such  minutiae  I  have  not 
deemed  it  expedient  to  exact  attention. 

A  chemical  class,  in  a  medical  school,  usually  consists  of  individuals, 
who  differ  widely  with  respect  to  their  taste  for  chemistry,  and  in  opinion 
as  to  the  extent  to  which  it  may  be  practicable  or  expedient  for  them  to 
iearn  it.  There  is  also  much  disparity  in  the  opportunities  which  they  may 
have  enjoyed,  of  acquiring  some  knowledge  of  this  science,  and  of  others 
which  are  subsidiary  to  its  explanation.  Hence  a  lecturer  may  expatiate 
too  much  for  one  portion  of  his  auditors,  and  yet  be  too  concise  for  another 
portion.  While  to  the  adept  he  may  often  appear  trite,  to  the  novice  he 
may  as  often  appear  abstruse. 

Some  pupils,  actuated  by  a  laudable  curiosity,  under  circumstances  per- 
mitting its  indulgence,  may  desire  an  accurate  knowledge  of  the  apparatus 
by  which  my  experimental  illustrations  are  facilitated:  other  pupils  may 
feel  themselves  justified,  perhaps  necessitated,  not  to  occupy  their  time  with 
the  acquisition  of  any  knowledge  which  is  not  indispensable  to  graduation. 

After  some  years'  experience  of  the  difficulties  abovementioned,  I  came 
to  the  conclusion,  that  the  time  spent  in  the  lecture  room  might  be  rendered 
much  more  profitable,  if  students  could  be  previously  apprized  of  the  chain 


PREFACE. 


of  ideas,  or  the  apparatus  and  experiments,  to  be  subjected  to  attention  at 
each  lecture  ;  especially  as  the  memory  might  afterwards  be  refreshed  by 
the  same  means.  In  consequence  of  this  conviction,  the  minutes  of  my 
course  of  instruction  were  printed  ;  and  subsequently  a  work,  comprising 
engravings  and  descriptions  of  the  larger  portion  of  such  of  my  apparatus 
and  experiments,  as  could  in  this  way  be  advantageously  elucidated.  En- 
couraged by  the  success  of  my  plan,  I  am  now  preparing  an  edition  which 
will  be  still  more  extensive.  The  work  thus  expanded,  I  have  entitled 
"  A  Compendium  of  the  Course  of  Chemical  Instruction  in  the  Medical 
School,"  &c. 

There  will  be  much  matter-in  the  Compendium,  respecting  which  I  shall 
not  question  candidates  at  the  examination  for  degrees.  With  the  essence 
of  the  larger  part,  I  shall  undoubtedly  expect  them  to  be  acquainted  ;  but 
other  portions  have  been  introduced,  that  I  may  not  be  obliged  to  dwell 
upon  them  in  my  lectures,  and  that  attention  to  them  may  be  optional  on 
the  part  of  the  students.  To  designate  the  portion  of  the  work,  respecting 
which  candidates  for  degrees  will  not  be  questioned,  I  have  had  it  printed 
in  a  smaller  type,  excepting  where  it  was  too  much  blended  with  subjects 
of  primary  importance  to  be  separated.  I  wish  it,  however,  to  be  under- 
stood, that  I  shall  expect  attention  to  the  parts  thus  distinguished,  so  far  as 
they  may  be  necessary  to  a  comprehension  of  the  rest.  Thus,  although  I 
do  not  deem  it  to  be  a  part  of  my  duty  to  question  a  pupil  on  pneumatics,  I 
shall  expect  him  to  understand  the  influence  of  atmospheric  pressure  upon 
chemical  reaction,  and  in  pneumato-chemical  operations. 

One  great  and  almost  self-evident  advantage,  resulting  from  my  under- 
taking, I  have  yet  to  mention;  I  allude  to  the  instruction  which  students 
may  derive  from  the  Compendium,  either  before  or  subsequently  to  their 
attendance  on  my  lectures,  and  especially  during  the  period  which  inter- 
venes between  their  first  and  second  course. 


PREFACE 

TO    THE    FOURTH   EDITION. 


THE  suggestions,  which  were  made  in  the  Preface  to  the  first  edition  of 
the  Compendium,  respecting  the  necessity  of  an  appropriate  text  book,  to 
aid  and  extend  the  instruction  afforded  by  the  course  of  chemical  lectures, 
delivered  in  the  Medical  Department  of  the  University  of  Pennsylvania,  have 
acquired  additional  force  since  that  Preface  was  written.  During  the  twelve 
intervening  years  the  boundaries  of  those  portions  of  human  knowledge  over 
which  Chemistry  has  established  a  rightful  domain,  have  undergone  an  ex- 
tension commensurate  with  the  time.  It  is,  of  course,  proportionably  more 
difficult  to  do  justice  to  the  whole  of  the  wonderful  region  comprised  within 
those  boundaries  in  sixty  lectures  delivered  within  four  months.  Formerly, 
the  attention  of  the  student  was  alternately  claimed  by  six  professors;  but 
latterly,  the  claims  of  a  seventh  professor  have  been  added  to  those  pre- 
viously established.  Nevertheless,  I  am  under  the  impression,  that  with  the 
assistance  which  my  text  books  are  competent  to  afford,  my  course  of  lec- 
tures, brief  as  it  is,  may  be  more  serviceable  to  a  student  who  makes  due 
use  of  those  text  books,  than  it  could  prove,  were  its  duration  doubled,  with- 
out being  associated  with  treatises  made  expressly  for  the  purpose  of  ampli- 
fying the  information  partially  afforded  by  my  lectures,  or  of  remedying 
their  inevitable  omissions. 

Having  been  prevented  by  indisposition  from  commencing  this  work  as 
early  as  expedient,  I  am  under  the  necessity  of  issuing  that  part  which  re- 
lates to  Caloric,  Light,  and  Inorganic  Chemistry  first.  Dynamic  Electri- 
city, comprising  Galvanism  or  Voltaic  Electricity,  and  Electro-magnetism, 
having  been  already  issued,  I  shall  in  the  next  place  republish  my  Treatise 
on  Mechanical  Electricity.  Then  to  complete  the  new  edition  of  my  text 
books,  only  Organic  Chemistry  will  remain  to  be  reprinted.  On  this  branch 
I  hope  to  furnish  a  treatise  before  I  reach  that  part  of  my  course  of  lectures, 
in  which  it  becomes  the  object  of  attention. 

I  am  in  hopes  that  numbering  the  paragraphs,  an  excellent  expedient  re- 
sorted to  by  me  for  the  first  time  in  this  edition,  will  be  found  advantageous 
to  the  reader,  by  rendering  references  from  one  part  of  the  work  to  another 
less  inconvenient,  and  consequently  more  frequent. 


CONTENTS. 


Page 
INTRODUCTION. 

Definition  of  Natural  Philosophy,  Chemistry,  and  Physiology  -  1 

Of  Chemical  reaction  -  2 

Of  repulsive  reaction,  or  repulsion  -  2 

I.  CALORIC. 

Experimental  proofs  of  a  material  cause  of  calorific  repulsion  3 
Expansion  -  6 
Expansion  of  solids          -  6 
Expansion  of  liquids       -  -  8 
Expansion  of  aeriform  fluids       -  -  10 
Thermometers  -  10 
Modification  of  the  effects  of  caloric  by  atmospheric  pres- 
sure -  14 
Capacities  for  heat,  or  specific  heat  -  44 
Slow  communication   of  heat,  comprising  the  conducting 

process  and  circulation         -  -  47 

Quick  communication  of  heat,  or  radiation  -  52 

Means  of  producing  heat,  or  rendering  caloric  sensible  -  57 

Means  of  producing  cold,  or  rendering  caloric  latent  -  68 

States  in  which  caloric  exists  in  nature       -  -  74 

II.  Light  -  75 

Sources  of  light  -  76 

Heating,  illuminating,  and  chemical  properties  of  the  rays  78 

Polarization  of  light  -  80 

PONDERABLE  MATTER. 

OF  CERTAIN    GENERAL  PROPERTIES   OF   PONDERABLE    MATTER  AND  THE   MEANS 

OF  ASCERTAINING  OR  INVESTIGATING  THEM  -  83 

SECT.  I.  Chemical  attraction  -  83 

Attraction  of  aggregation,  or  cohesion         -  -  83 

Crystallization  84 

Chemical  affinity,  or  heterogeneous  attraction  -  89 

II.  Definite  proportions                                   -              -              -  -  93 

Tables  of  chemical  equivalents  -  94 

Atomic  theory         -  .  95 

Chemical  symbols  -  96 

Atomic  weights  and  symbols  of  the  simple  substances  -  97 

III.  Specific  gravity                                        -              -              -  -  98 

Definition  and  discovery  of  the  aeriform  fluids  called  gases  '105 

INORGANIC  CHEMISTRY;   OR  CHEMISTRY  OF  INORGANIC 
SUBSTANCES. 

Individual  ponderable  elements  -  110 

BASACIGEN  ELEMENTS                                                                                 -  .  no 

SECT.  I.  Oxygen  .  no 

II.  Chlorine         -  -  117 

Compounds  of  chlorine  with  oxygen  -  123 

Hypochlorous  acid,  or  protoxide  of  chlorine             -  -  124 


Ylll  CONTENTS. 

Page 

Euchlorine,  or  impure  chlorous  acid  125 

Chloric  acid  -  126 

Oxychloric,  or  perchloric  acid  -  127 

III.  Bromine          -  -  128 

Compounds  of  bromine  with  oxygen  and  chlorine  -  129 

Bromic  acid          -                             -  -  1 29 

Chloride  of  bromine  -  130 

IV.  iodine  -  130 

Compounds  of  iodine  with  oxygen  -  133 

lodic,  hyperiodic,  and  iodous  acid  -  133 

Chlorides  and  bromides  of  iodine               -  -  133 

V.  Fluorine                                                       -              -  -              -  134 

VI.  Sulphur  -  134 

Compounds  of  sulphur  with  oxygen  -  137 

Hyposulphurous  acid       -  -  137 

Sulphurous  acid                                              -  -  137 

Hyposulphuric  acid         -                            .  -  138 

Sulphuric  acid  -  139 

Chlorides,  bromide,  and  iodide  of  sulphur  -  140 

VII.  Selenium       -  -  140 

Compounds  of  selenium  with  oxygen  -  141 

VIII.  Tellurium       -  142 

RADICALS  -  143 

NON-METALLIC  RADICALS  -  143 

SECT.  I.  Hydrogen  -  143 

Compounds  of  hydrogen  with  oxygen  -  150 

Water     -  -  150 

Deutoxide  or  bioxide  of  hydrogen  -  156 

Compound  of  hydrogen  with  chlorine          -  -  160 

Chlorohydric  or  muriatic  acid  gas  -  160 

Old  theory  of  the  nature  of  chlorine  and  chlorohydric  acid  165 

Bromohydric  acid  -  165 

lodohydric  acid  •  165 

Compounds  of  hydrogen  with  sulphur         -  -  166 

Sulphydric  acid,  or  sulphuretted  hydrogen  -  167 

Polysulphide  of  hydrogen  -  170 

Compounds  of  hydrogen  with  selenium  and  tellurium         -  171 

Selenhydric  acid,  or  selenuretted  hydrogen  -  171 

Telluhydric  acid,  or  telluretted  hydrogen  -  171 

II.  Nitrogen  or  azote         -  -  172 

Atmospheric  air  -  174 

Chemical  compounds  of  nitrogen  with  oxygen  -              -  179 

Protoxide  of  nitrogen,  or  nitrous  oxide  -  179 

Nitric  oxide,  or  nitrous  air  -  182 

Hyponitrous  acid  -  183 

Nitrous  acid        -  -  184 

Theory  of  volumes       -  -  187 

Nitric  acid  -  190 

Nitroso-nitric  acid        -  -  192 

Compounds  of  nitrogen  with  chlorine  and  iodine  -              -  195 

Some  points  of  chemical  theory       -  -  195 

Theories  of  combustion  -  196 

Influence  of  the  habitudes  of  chemical  agents  with  the 

Voltaic  series,  on  classification  and  nomenclature  198 
Methods  of  distinguishing  degrees  of  oxidizement,  de- 
rived from  the  school  of  Lavoisier  -  199 
Origin  of  the  erroneous  idea  of  an  acidifying  principle     -  200 
Acidity  -  201 
Alkalinity  -  202 
Compounds  of  nitrogen  with  hydrogen  204 


CONTENTS.  IX 


Ammonia,  or  the  volatile  alkali  -  204 

Ammonium     -  -  208 

SECT.  III.  Phosphorus     -  -  211 

Compounds  of  phosphorus  with  oxygen       -  -  214 

Oxide  of  phosphorus        -  -  215 

Hypophosphorous  acid  -  215 

Phosphorous  acid  -  215 

Phosphoric  acid  -  216 

Chlorides  of  phosphorus      -  -  217 

Bromides  and  iodides  of  phosphorus  -  217 

Sulphides  and  selenides  of  phosphorus         -  217 

Compounds  of  phosphorus  with  hydrogen  -  218 

Protophosphuretted  hydrogen      -  -  218 

Perphosphuretted  hydrogen         -  -  218 

IV.  Carbon  -  220 

Compounds  of  carbon  with  oxygen  -  224 

Carbonic  oxide  -  224 

Carbonic  acid      -  -  225 

Oxalic  acid  -  231 

Mellitic  acid        -  -  232 

Croconic  acid      -                                                        -  -  232 

Compounds  of  carbon  with  oxygen  and  chlorine      -  -  232 

Chloral                                             -  -  232 

Chloroxycarbonic  acid     -  -  233 

Chlorides  of  carbon  -  233 

Bromide  of  carbon  -  233 

Iodides  of  carbon    -  -  233 

Sulphocarbonic  acid,  or  bisulphide  of  carbon  -  234 

Compounds  of  carbon  with  hydrogen  -  234 

Light  carburetted  hydrogen,  or  fire  damp  -  236 

Safety  lamp     -  -  236 

Deutocarbohydrogen,  or  olefiant  gas        -  -  237 

Certain  gaseous  compounds  formed  by  igniting  gaseous 

elements  of  water  with  olefiant  gas,  &c.  -  238 

Other  varieties  of  carbohydrogen  -  240 

Bicarburet  of  hydrogen  -  240 

Naphthaline  -  240 

Compounds  of  carbon  with  chlorine  and  hydrogen  -  241 

Compound  of  carbon  with  nitrogen  -  241 

Bicarburet  of  nitrogen,  or  cyanogen          -  -  241 

Nomenclature  of  the  compounds  of  cyanogen  -  242 

Cyanic,  cyanuric,  and  fulminic  acid  -  243 

Chlorides,  bromides,  and  iodides  of  cyanogen  -  245 

Sulphocyanogen  -  245 

Sulphocyanhydric  acid         -  -  245 

Cyanhydric  or  prussic  acid      -  -  246 

V.  Boron  -  249 

Compound  of  boron  with  oxygen  -  250 

Boric  or  boracic  acid       -                                                      '  -  250 

Chloride  of  boron  -  251 

VI.  Silicon  -  251 

Compound  of  silicon  with  oxygen  -  253 

Silica,  or  silicic  acid        -  -  253 

Glass  -  254 

Compounds  of  fluorine  with  hydrogen,  boron,  and  silicon     -  255 

Fluohydric  acid  -  256 

Fluoboric  acid     -             -  -  256 

Fluosilicic  acid  -  257 

Reaction  of  fluohydric  acid  with  fluoboric  and  fluosilicic 

acid  -  258 
«* 


X  CONTENTS. 

Page 

SECT.  VII.  Zirconion  259 
METALLIC  RADICALS 

METALS  OF  THE  EARTHS  PROPER 

SECT.  I.  Aluminium     -  -  264 

Alumina     -  -  265 

Chloride  of  aluminium        -  -  268 

II.  Glucinium      -  -  268 

Glucina      -  -  269 

III.  Yttrium  -  269 

Yttria         -  -  269 

IV.  Thorium          -  -  269 

Thorina      -  -  270 

METALS  OF  THE  ALKALINE  EARTHS  -  270 

SECT.  I.  Magnesium     -  -  270 

Magnesia  -              -  270 

II.  Calcium,  barium  and  strontium  -  271 

Evolution  of  calcium,  barium  and  strontium  -  272 

III.  Lime,  or  calcia,  the  oxide  of  calcium  -  273 

Baryta        -  -  275 

Strontia      -  -  277 

Peroxides  or  bioxides  of  barium  and  strontium  -             -  277 

METALS  OF  THE  ALKALIES,  OR  ALKALIFIABLE  METALS     -  -  278 

SECT.  I.  Potassium       -  -  278 

II.  Sodium  -  279 

Potash  or  potassa,  and  soda                           -  -  280 

Peroxides  and  suboxides  of  potassium  and  sodium  -  283 

III.  Lithium  -  284 

Lithia         -  -  284 

Reaction  of  chlorine,  bromine,  iodine,  fluorine,  and  cyanogen, 

with  the  metals  of  the  earths  and  alkalies  -  284 
Reaction  of  sulphur,  selenium,  and  tellurium,  with  the  metals 

of  the  earths  and  alkalies  -  288 

METALS  PROPER  -  289 

SECT.  I.   Gold  -  290 

Compounds  of  gold  with  oxygen     -  -  291 

Compounds  of  gold  with  the  halogen  class  -  292 

Compounds  of  gold  with  sulphur    -  -  292 

II.  Platinum         -  -  293 

Compounds  of  platinum  with  oxygen  -  294 

Compounds  of  platinum  with  the  halogen  class  -             -  294 

Compounds  of  platinum  with  sulphur          -  -  296 

Power  of  platinum  and  other  metals  in  a  divided  or  spongy 

form  to  induce  chemical  reaction      -  -  296 

III.  Silver  -  297 

Compounds  of  silver  with  oxygen  -  298 

Compounds  of  silver  with  the  halogen  class  -  299 

Compounds  of  silver  with  sulphur  -  299 

IV.  Mercury                                                  -  -  300 

Compounds  of  mercury  with  oxygen            -  -  302 

Reaction  of  acids  with  mercury  and  its  oxides  -              -  303 

Chlorides  of  mercury  -  304 

Bromides,  iodides,  fluorides,  and  cyanides  of  mercury          -  307 

Compounds  of  mercury  with  sulphur  -  308 

Phosphurets  of  mercury      -  -  309 

Combustion  of  mercury  with  chlorine  -  309 

V.  Copper  .  310 

Compounds  of  copper  with  oxygen  -  312 

Compounds  of  the  oxides  of  copper  with  acetic  acid  -  314 

Compounds  of  copper  with  /the  halogen  class  -  314 

Compounds  of  copper  with  sulphur  and  selenium  -  315 


CONTENTS.  XI 

Page 

VI.  Lead  -  315 
Compounds  of  lead  with  oxygen  -  316 
Compounds  of  the  protoxide  of  lead  with  acetic  acid  -  318 
Carbonate  of  lead  -  318 
Compounds  of  lead  with  the  halogen  class  -  319 
Compounds  of  lead  with  sulphur  and  selenium  -  -  319 
SECT.  VII.  Tin  -  -  320 
Compounds  of  tin  with  oxygen  -  -  320 
Compounds  of  tin  with  the  halogen  class  -  321 
Compounds  of  tin  with  sulphur  and  selenium.  -  321 
VIII.  Bismuth  -  322 
Compounds  of  bismuth  with  oxygen  -  323 
Compounds  of  bismuth  with  the  halogen  class  -  -  323 
Compounds  of  bismuth  with  sulphur  and  selenium  -  324 
IX.  Iron  -  324 
Compounds  of  iron  with  carbon,  boron,  silicon,  and  phos- 
phorus -  325 
Compounds  of  iron  with  oxygen  -  -  326 
Reaction  of  iron  with  acids  -  328 
Compounds  of  iron  with  the  halogen  class  -  329 
Compounds  of  iron  with  sulphur  and  selenium  -  -  330 
X.  Zinc  -  331 
Compounds  of  zinc  with  oxygen  -  -  331 
Compounds  of  zinc  with  the  halogen  class  -  333 
Compounds  of  zinc  with  sulphur  and  selenium  -  -  333 
XI.  Arsenic  -  334 
Compounds  of  arsenic  with  oxygen  -  335 
Compounds  of  arsenic  with  the  halogen  class  -  338 
Compounds  of  arsenic  with  sulphur  and  selenium  -  338 
Compounds  of  arsenic  with  phosphorus  and  hydrogen  -  339 
Means  of  detecting  arsenic  in  cases  where  poisoning  is  sus- 
pected by  it  -  340 
XII.  Antimony  -  -  344 
Sesquioxide  of  antimony  -  -  345 
Compounds  of  antimony  with  oxygen  of  minor  importance  346 
Compounds  of  antimony  with  the  halogen  class  -  -  347 
Compounds  of  antimony  with  sulphur  and  selenium  -  347 
XIII.  Metals  proper  of  minor  importance  -  -  -  350 
Palladium  -  -  -  -  350 
Rhodium  -  -  350 
Iridium  -  -  351 
Osmium  -  -  351 
Nickel  -  -  351 
Cadmium  -  -  352 
Chromium  -  352 
Cobalt  -  -  .  354 
Columbium  -  354 
Manganese  -  -  354 
Molybdenum  -  354 
Titanium  -  355 
Tungsten  -  355 
Uranium  -  -  355 
Cerium  -  -  355 
Vanadium  -  355 
SALTS  •  -  356 
SECT.  I.  Oxysalts  -  359 
Chlorates  and  hypochlorites  -  359 
Oxychlorates  -  354 
Nitrates  -  -  364 
Nitrites  and  hyponitrites  -  -  365 


Xll  CONTENTS. 

Page 

Sulphates  365 

Hyposulphates,  sulphites,  and  hyposulphites  366 

Seleniates  -  366 

Phosphates  -  366 

Phosphites  -  366 

Carbonates  -  367 

Borates       -  -  367 

Silicates      -  -  367 

Cyanates  and  fulminates     -  c  368 

Double  oxysalts      -                                                        -  -  368 

SECT.  II.  Sulphosalts  -  369 

III.  Selenisalts  and  tellurisalts      -  -  369 

IV.  Chlorosalts,  bromosalts,  iodosalts,  and  fluosalts  -  370 
V.  Cyanosalts    -  -  370 


DEFINITIONS  OF  CHEMISTRY. 

It  is  natural  that  a  person  whose  attention  may  be  directed  to  chemistry, 
should  inquire  of  what  does  it  treat,  or  how  is  it  to  be  defined  or  distin- 
guished from  other  sciences  1 

Agreeably  to  the  definition  given  in  the  second  page  of  the  Compendium, 
chemistry  treates  of  those  phenomena  and  operations  of  nature  which  arise 
from  reaction  between  particles  of  inorganic  matter. 

I  subjoin  several  other  definitions  from  some  of  the  most  celebrated 
modern  writers  on  chemistry. 

Thomson  defines  chemistry  to  be  "  the  science  which  treats  of  those 
events  or  changes  in  natural  bodies,  which  are  not  accompanied  by  sen- 
sible motions." 

Henry  conceives  that  "  it  may  be  defined,  the  science  which  investigates 
the  composition  of  material  substances,  and  the  permanent  changes  of 
constitution,  which  their  mutual  actions  produce." 

According  to  Murray,  "  it  is  the  science  which  investigates  the  combi- 
nations of  matter,  and  the  laws  of  those  general  forces,  by  which  these 
combinations  are  established  and  subverted." 

Brande  alleges  "that  it  is  the  object  of  chemistry  to  investigate  all 
changes  in  the  constitution  of  matter,  whether  effected  by  heat,  mixture,  or 
other  means." 

According  to  Z7re,  "  chemistry  may  be  defined  that  science,  the  object 
of  which  is  to  discover  and  explain  the  changes  of  composition  that  occur 
among  the  integrant  and  constituent  parts  of  different  bodies." 

The  definition  given  by  Berzelius  is  as  follows : — "  Chemistry  is  the 
science  which  makes  known  the  composition  of  bodies,  and  the  manner  in 
which  they  comport  with  each  other." 


COMPENDIUM 

OF 

CHEMICAL  INSTRUCTION, 

&c. 


INTRODUCTION. 

1.  The  phenomena  and  operations  of  the  material  world 
appear  to  be  dependent  on  certain  properties  in  the  parti- 
cles or  masses  of  matter  which  enable  them  to  exercise 
a  reciprocal  influence.     Without  this  reciprocal  action, 
which  I  would  prefer  to  call  reaction,*  every  particle  or 
mass  would  be  as  if  no  other  existed,  and  could  itself  have 
no  efficient  existence. 

2.  The  reciprocal  action  or  reaction,  thus  inferred  to 
exist,  may  be  distinguished  as  taking  place  between  masses, 
between  a  mass  and  particles,  and  between  particles  only. 

3.  Reaction  between  masses}  is  sublimely  exemplified  in 
the  solar  system,  by  that  attraction  between  the  sun  and 
planets,  by  which  they  are  made  to  revolve  in  their  orbits. 

4.  Reaction  between  a  mass  and  particles  is  exemplified 
by  the  reflection,  refraction,  and  polarization  of  light. 

5.  Reaction  between  particles  is  exemplified  by  a  fire,  or 
the  explosion  of  gunpowder. 

Definition  of  Natural  Philosophy,  Chemistry,  and 
Physiology. 

6.  Natural  Philosophy,  in  its  most  extensive  sense,  treats 
of  physical  reaction  generally.     In  its  more  limited  and 

*  In  Mechanics,  action  is  said  to  produce  reaction ;  but  in  the  case  of  an  innate 
property,  which  mutually  causes  different  portions  of  matter  to  be  self  attractive, 
or  repellent,  it  is  impossible  to  distinguish  the  agent  from  the  reagent.  From  our 
first  acquaintance  with  any  bodies  so  situated,  they  may  be  said  mutually  to  react, 
or  to  exercise  reaction. 

t  By  the  word  mass,  I  mean  a  congeries  of  particles  capable  of  producing  some 
effect  collectively,  to  which  severally  they  would  be  incompetent. 
1 


2  INTRODUCTION. 

usual  acceptation,  it  treats  of  those  phenomena  and  ope- 
rations of  nature,  which  arise  from  reaction  between 
masses,  or  between  a  mass  and  particles. 

7.  Chemistry  treats  of  the  phenomena  and  operations  of 
nature,  which  arise  from  the  reaction  between  the  particles 
of  inorganic  matter. 

8.  Physiology  treats  of  the  phenomena  and  operations, 
which  arise  from  the  reaction  of  the  masses  or  atoms  of 
organic  or  living  bodies. 

OF  CHEMICAL  REACTION. 

9.  Reaction  between  particles,  or  chemical  reaction,  is 
distinguished   into  repulsive  reaction   or   repulsion,   and 
attractive  reaction  or  attraction. 

OF  REPULSIVE  REACTION  OR  REPULSION. 

A  Priori  Proofs  that  there  must  be  a  Matter  in  which  Re- 
pulsion exists  as  an  Inherent  Property. 

10r  Matter  may  be  defined  to  be  that  which  has  proper- 
ties. We  know  nothing  of  matter  directly.  It  is  only 
with  its  properties  that  we  have  a  direct  acquaintance.  It 
is  from  our  perception  of  matter,  through  the  powers  or 
properties  by  which  it  affects  our  senses,  that  we  believe 
in  its  existence. 

11.  The  existence  of  repulsion  and  attraction  is  as  evi- 
dent as  that  of  the  matter  which,  in  obedience  to  their 
successive  predominancy,  may  be  seen  either  to  cohere,  in 
solids,  with  great  tenacity,  or  to  fly  apart  with  explosive 
violence  in  the  state  of  a  vapour.     The  existence  of  re- 
pulsion and  attraction  being  proved,  it  must  be  admitted 
that  they  are  properties  of  matter ;  since  the  existence  of 
a  property,  independently  of  matter,  is  inconceivable.   But 
being  of  a  nature  to  counteract  each  other,  the  repellent 
and  attractive  powers  cannot  coexist  in  particles  of  the 
same  kind,  and  consequently  must  belong  to  particles  of 
different  kinds.     There  must,  therefore,  be  a  matter  en- 
dowed with  repulsion,  distinct  from  that  which  is  endowed 
with  attraction. 

12.  I  conceive  that  the  phenomena  of  chemistry  demon- 
strate that  there  are  at  least  the  three  following  properties, 
which,  from  their  obvious  incompatibility,  cannot  belong 
to  the  same  elementary  particles. 


INTRODUCTION.  .5 

13.  1st.  An  innate  property  of  reciprocal  attraction. 

14.  2d.  An  innate  property  of  counteracting  attraction 
directly,  by  imparting  reciprocal  repulsion. 

15.  3d.  An  innate  property  of  imparting  an  attraction, 
variable  in  its  force,  and  limited  and  contingent  in  its  du- 
ration. 

16.  I  presume  that  there  must  be  at  least  three  different 
kinds  of  matter,  to  each  of  which,  one  of  the  properties 
thus  specified  innately  appertains. 

17.  The  permanent  and  unvarying  attractive  power  is 
exemplified  by  gravitation,  and,  as  modified  by  circum- 
stances, by  tenacity,  or  cohesion. 

18.  It  resides,  undoubtedly,  in  every  kind  of  matter  en- 
dowed with  weight,  and  consequently  in  all  that  is  consi- 
dered as  material  by  the  mass  of  mankind. 

19.  It  must  likewise  act  between  each  of  those  impon- 
derable principles  which  I  am  about  to  mention,  and  all 
other  matter,  whether  ponderable  or  imponderable. 

20.  The  power  of  imparting   reciprocal   repulsion   to 
ponderable  matter  is  supposed  by  chemists  generally  to 
belong  to  certain  imponderable  material  reciprocally  repul- 
sive particles,  constituting  the  cause  of  heat,  called  ca- 
loric. 

21.  The  power  of  indirectly  counteracting  attraction, 
and  substituting  for  it  a  contingent  and  variable  attraction, 
appears  to  belong  to  electricity.     Light  also  appears  to 
exercise  a  modifying  influence. 

22.  Thus  we  have  reason  to  infer  the  existence  of  at 
least  three  imponderable  substances — electricity,  caloric, 
and  light — each  consisting  of  particles  reciprocally  repul- 
sive, yet  attractive  of  other  matter,  and  probably  more  or 
less  attractive  of  each  other. 

OF  CALORIC. 

Experimental  Proofs  of  the  Existence  of  a  material  Cause 
of  Calorific  Repulsion. 

23.  It  has  been  ascertained  that  ice  melts  and  water 
freezes  at  the  temperature  of  32°  of  Fahrenheit's  thermo- 
meter.   If  at  this  temperature,  which  is  called  the  freezing 
point,  ice  in  a  divided  state,  as  in  that  of  snow  for  in- 
stance, be  mingled  with  an  equal  weight  of  water  at  172°, 


4  INTRODUCTION. 

the  ice  will  be  melted,  and  the  resulting  temperature  will 
be  32° ;  but  if  equal  weights  of  water  be  mingled  at  those 
temperatures,  the  mixture  will  have  the  mean  heat  of  102°. 

24.  It  follows  that  a  portion  of  heat  becomes  latent  in 
the  aqueous  particles  during  the  liquefaction  of  the  ice, 
sufficient  to  raise  an  equal  weight  of  water  one  hundred 
and  forty  degrees.     In  this  case  the  ice  is  supposed  to 
combine  with  material  calorific  particles,  innately  endowed 
with  a  power  of  reciprocal  repulsion,  and  likewise  with 
that  of  combining  with  ponderable  matter.     Hence  wrater 
is  considered  as  a  combination  of  ponderable  particles, 
endowed  with  a  reciprocally  attractive  power,  and  impon- 
derable particles  endowed  with  a  reciprocally  repellent 
power ;  so  that,  in  obedience  to  the  power  last  mentioned, 
the  compound  atoms,  instead  of  cohering  as  in  the  solid 
state,  move  freely  among  each  other,  forming  consequently 
a  liquid. 

25.  In  all  cases  of  liquefaction  or  fusion  which  have 
been   examined,  analogous  results   have  been  observed; 
whence  it  is  generally  believed  that  whenever  a  solid  is 
converted  into  a  liquid,  its  particles  unite  with  a  portion  of 
the  material  cause  of  heat,  which  becomes  latent,  as  in  the 
case  of  ice  in  melting.     The  evidence  is  equally  strong  in 
favour  of  the  inference  that  in  passing  from  the  liquid  to 
the  aeriform  state,  ponderable  matter  combines  with,  and 
renders  latent  even  a  larger  quantity  of  heat  in  proportion 
to  its  weight,  than  in  cases  of  liquefaction. 

26.  When,  by  means  of  a  thermometer,  we  observe  the 
rise  of  temperature  in  water  exposed  to  a  regular  heat,  as 
when  placed  in  a  cup  upon  a  stove,  we  find  that  nearly 
equal  increments  of  heat  are  acquired  in  equal  times,  until 
the  boiling  point  is  attained.     Subsequently,  the  cup  being 
open  so  as  to  allow  the  steam  to  escape  freely,  no  further 
rise  of  temperature  will  be  found  to  ensue;  but  in  lieu  of 
it,  steam  will  be  evolved  more  or  less  copiously,  in  propor- 
tion to  the  activity  of  the  fire.     Since  from  the  time  the 
water  boils  it  ceases  to  grow  hotter,  it  may  be  fairly  pre- 
sumed that  the  steam  generated  during  the  ebullition,  al- 
though of  a  temperature  no  higher  than  212°,  contains,  in 
a  latent  state,  the  caloric  which  meanwhile  enters  the 
liquid.     This  presumption  is  fully  justified  by  the  fact,  that 
if  any  given  weight  of  steam  be  received  in  a  quantity  of 


CALORIC.  O 

cool  water  ten  times  heavier,  it  will  cause  in  it  a  rise  of 
temperature  of  nearly  one  hundred  degrees. 

27.  The  heat  which  would  raise  ten  parts  of  water  to 
100  degrees,  would,  if  concentrated  into  one  of  those  parts, 
raise  it  to  1000  degrees  nearly,  which  is  about  equal  to  a 
red  heat.     It  follows,  therefore,  that  as  much  heat  is  ab- 
sorbed in  producing  steam,  as  would  render  the  water  of 
which  it  consists  red-hot,  if  prevented  from  assuming  the 
aeriform  state. 

28.  These  facts  and  deductions  induce  chemists  general- 
ly to  believe  that  the  cause  of  calorific  repulsions  is  mate- 
rial; that  it  consists  of  a  fluid,  of  which  the  particles  are 
self-repellent,  while  they  attract  other  matter;  that  by  the 
union  of  this  fluid  with  other  matter,  a  repulsive  property 
is  imparted,  which  counteracts  cohesion,  so  as  to  cause, 
successively,  expansion,  fusion,  afel^  the  aeriform    state ; 
and  further,  that  it  is  by  the  afflux  of  the  calorific  matter 
that  the  sensation  of  heat  is  produced,  while  that  of  cold 
results  from  its  efflux. 

4*        * 

Acceptation  of  the  term  Cal\-ic.\  .     ^ 

29.  If  we  place  a  small  heap  of  fulminating  mercury 
upon  the  face  of  a  hammer,  and  strike  it  duly  with  another 
hammer,  an  explosion  will  ensue  so  violent  as  to  cause  a 
visible  indentation  in  the  steel  surface.     This  explosion, 
agreeably  to  the  premises,  can  only  be  explained  by  sup- 
posing the  evolution  of  a  great  quantity  of  the  material 
cause  of  heat.     Were  an  equal  quantity  of  red-hot  sand  to 
be  suddenly  quenchecl  with  water,  the  effect  would  be  com- 
paratively feeble.     We  may,  therefore,  infer  that  the  ful- 
minating powder,  though  cold,  contains  more  of  the  cause 
of  heat  than  a  like  quantity  of  red-hot  sand.     Hence  it 
would  follow  from  using  the  word  heat  in  the  sense  both 
of  cause  and  effect,  that  there  is  more  heat  in  a  cold  body 
than  in  a  hot  one,  which  in  language  is  a  contradiction. 
On  this  account  it  was  considered  proper  by  the  chemists 
of  the  Lavoisierian  school,  to  use  a  new  word,  caloric,  to 
designate  the  material  cause  of  calorific  repulsion. 

Experimental  Illustration. 

30.  A  portion  of  fulminating  mercury  exploded  between 
two  hammers. 


IMPONDERABLE    SUBSTANCES. 


ORDER  PURSUED  IN  TREATING  OF  CALORIC. 

EXPANSION. — MODIFICATION  OF  THE  EFFECTS  OF  CALORIC  BY  ATMOS- 
PHERIC PRESSURE. — CAPACITIES  FOR  HEAT,  OR  SPECIFIC  HEAT. — 
SLOW  COMMUNICATION  OF  HEAT,  COMPRISING  THE  CONDUCTING  PRO- 
CESS AND  CIRCULATION. — QUICK  COMMUNICATION  OF  HEAT,  OR  RA- 
DIATION.— MEANS  OF  PRODUCING  HEAT,  OR  RENDERING  CALORIC  SEN- 
SIBLE.— MEANS  OF  PRODUCING  COLD,  OR  RENDERING  CALORIC  LATENT. 
— STATES  IN  WHICH  CALORIC  EXISTS  IN  NATURE. 


EXPANSION. 

OF  THE  EXPANSION  OF  SOLIDS,  LIQUIDS,  AND  ELASTIC  FLUIDS, 
AND  ON  THE  OPPONENT  AGENCY  OF  ATMOSPHERIC  AND  OTHER 
PRESSURE. 

Expansion  of  Solids. 

31.  A  ring  and  plug,  which  when  cold  fit  each  other, 
cease  to  do  so  when  either  is  heated;  and  a  tire  when  red- 
hot  is  made  to  embrace  a  wheel  otherwise  too  large  for  it. 

Pyrometer,  in  which  the  Extension,  in  length,  of  a  Metallic  Bar  is  ren- 
»       dered  fensible  by  a  Combination  of  Levers. 

32.  The  influence  of  temperature  on  the  length  of  a  metallic  wire  may  be 
rendered  evident  by  means  of  the  instrument,  of  which  fig.  1,  in  the  oppo- 
site engraving  is  a  representation. 

33.  WW,  represents  a  wire,  beneath  which  is  a  spirit  lamp  consisting 
of  a  long,  narrow,  triangular  vessel  of  sheet  copper,  open  along  the  upper 
angle,  so  as  to  receive  and  support  a  strip  of  thick  cotton  cloth,  or  a  suc- 
cession of  wicks.     By  the  action  of  the  screw  at  S  the  wire  is  tightened, 
and  by  its  influence  on  the  levers,  the  index  I  is  raised.     The  spirit  lamp 
is  then  lighted  and  the  wire  enveloped  with  flame.     It  is  of  course  heated 
and  expanded,  and,  allowing  more  liberty  to  the  levers,  the  index  upheld 
by  them  falls. 

34.  By  the  action  of  the  screw  the  wire  may  be  again  tightened,  and,  the 
application  of  the  lamp  being  continued,  will  again,  by  a  further  expan- 
sion, cause  the  depression  of  the  index ;  so  that  the  experiment  may  be 
repeated  several  times  in  succession. 

35.  Since  this  figure  was  drawn,  I  have  substituted  for  the  alcohol  lamp 
the  more  manageable  flame  of  hydrogen  gas,  emitted  from  a  row  of  aper- 
tures in  a  pipe  supplied  by  an  apparatus  for  the  generation  of  that  gas. 
See  fig.  2. 

36.  If,  while  the  index  is  depressed  by  the  expansion,  ice  or  cold  water 
be  applied  to  the  wire,  a  contraction  immediately  follows  so  as  to  raise  the 
index  to  its  original  position. 

37.  Metals  are  the  most  expansible  solids,  but  some  are  more  expansible 
than  others. 

38.  The  following  table,  abstracted  by  Turner  from  that  furnished  by 
Lavoisier,  will  show  the  increase  of  bulk  obtained  by  glass  and  various  me- 
tals in  rising  in  temperature  from  32°  to  212°. 


Instrument 
far  demonstrating  the  Power  of  Caloric  in  expanding  a  Metallic  Rod. 


(Page  6.) 


CALORIC. 

Atau.  cf  Subnets. 

Glass  tube  without  lead,  mean  of  three  specimens        -        -         1-1115  of  its  length. 

English  flint  glass,        - 1-1248 

Copper, 1-581 

Brass,  mean  of  two  specimens, -532 

Soft  iron,  forged, 819 

Iron  wire,     --- -812 

Untempered  steel, 927 

Tempered  steel, 807 

Lead, '     -  .351 

Tin  of  India, 516 

Tin  of  Falmouth, 462 

Silver, 524 

Gold,  mean  of  three  specimens, -602 

Platinum,  determined  by  Borda, 1-1167 

39.  Pyrometers  have  been  made  of  platinum,  in  one  of  which,  invented 
by  Daniell,  changes  in  the  length  of  a  cylinder  of  this  metal,  arising  from 
temperature,  are  made  sensible  by  the  motion  of  a  lever  associated  with  it, 
and  which  acts  as  an  index.     In  the  other,  a  bulb  is  formed  of  platinum, 
and  the  degree  of  heat  is  inferred  from  the  quantity  of  air  expelled. 

40.  The  use  of  this  air  pyrometer  is  burdened  by  the  necessity  of  mea- 
surement and  calculation  to  ascertain  the  result.     This  might  be  very  much 
facilitated  by  the  use  of  a  sliding  rod  and  air-gauge.     The  retraction  of 
the  rod  might  be  made  to  compensate  the  expulsion  of  air,  while  divisions 
well  made  on  it  would  indicate  the  quantity. 

Experimental  Illustration  of  the  different  Expansibility  of 

Metals. 

41.  That  the  expansibility  of  one  metal  may  exceed  that 
of  another,  may  be  rendered  apparent  by  soldering  to- 
gether, face  to  face,  two  thin  strips,  one  iron  the  other 
brass.     On  exposure  to  heat,  the  compound  strip,  thus 
constituted,  assumes  the  shape  of  an  arch.     The  brass, 
which  is  the  more  expansible  metal,  forms  the  outer  and  of 
course  larger  curve. 

Supposed  Exception  to  the  Law  that  Solids  expand  by  Heat 
in  the  case  of  Clay,  which  contracts  in  the  Fire. 

42.  The  phenomena  do  not  justify  us  in  considering  the 
contraction  of  clay  from  heat  as  an  exception  to  the  ge- 
neral law.     In  the  first  instance  clay  shrinks  by  losing 
water,  of  which  the  last  portions  are  difficult  to  expel.     In 
the  next  place  a  chemical  union  takes  place  between  the 
principal  ingredients,  silica  and  alumina,  which  is  rendered 
more  complete  in  proportion  to  the  duration  and  intensity 
of  the  fire.     It  may  be  presumed  that  the  vitreous  com- 


8 


IMPONDERABLE  SUBSTANCES. 


pound,  which  would  result  from  a  complete  fusion  and 
combination  of  the  constituents,  would  be  as  expansible  as 
other  vitreous  substances. 

Experimental  Illustration. 

43.  The  contraction  produced  by  heat  in  cylinders  of 
clay  shown  by  means  of  the  ingenious  but  inaccurate  pyro- 
meter of  Wedgwood. 

Expansion  of  Liquids  or  non-elastic  Fluids. 

44.  The  word  fluid  applies  to  every  mass  that  will  flow, 
distribute  itself  equally  in  obedience  to  its  own  weight  or 
self-repulsion. 

45.  Ponderable  fluids  are  either  elastic  or  non-elastic. 
Latterly  the  term  liquid  has  been  employed  to  designate 
those  fluids  which  are,  like  water,  alcohol,  and  oil,  devoid 
of  elasticity,  a  property  which,  in  due  time,  I  shall  define 
and  illustrate. 

Liquids  are  expanded  when  their  Temperature  is  raised,  and 
some  Liquids  are  more  expansible  than  others. 


N 


N 


IlilllllillllillllllliilHIii 


CALORIC. 


46.  Let  two  glass  vessels  be  provided  with  bulbs  and 
necks  of  the  same  shape  and  dimensions  as  represented  in 
the  preceding  figure.    Let  one  of  them,  that  on  the  left  for 
instance,  be  supplied  with  as  much  alcohol  as  will  occupy 
it  to  the  level  designated  by  the  letters  O  O.    Let  the  ves- 
sel on  the  right  be  occupied  with  water  to  the  same  level, 
the  height  of  the  liquid  in  each  being  made  to  correspond 
with  a  little  fillet  of  white  paper  secured  about  the  neck. 
Under  each  vessel,  place  equal  quantities  of  charcoal,  burn- 
ing with  a  similar  degree  of  intensity ;  or  preferably,  sur- 
round the  bulbs  simultaneously  with  hot  water  in  an  oblong 
vessel  of  suitable  dimensions.     The  liquids  in  each  vessel 
will  be  expanded  so  as  to  rise  into  the  necks;  but  the  alco- 
hol will  rise  to  a  greater  height  than  the  water. 

47.  The  dilatation  of  the  following  liquids,  by  a  change 
of  temperature  from  32°  to  212°,  is  as  follows — alcohol  1-9, 
nitric  acid  1-9,  fixed  oils  1-12,  sulphuric  ether  1-14,  oil  of 
turpentine   1-14,  sulphuric  or  muriatic  acid  1-17,  brine 
1-20,  water  1-23  nearly,  mercury  about  1-55. 

48.  The  rate  of  expansion  for  liquids  increases  with  the 
temperature;  as  if  their  particles,  by  becoming  more  re- 
mote, lost  some  of  their  ability  to  counteract  the  repulsive 
influence  of  caloric. 

49.  The  number  associated  with  each  of  the  substances 
in  the  following  list,  shows  its  melting  point  as  estimated  by 
Fahrenheit's  scale.  One  degree  of  Daniell's  pyrometer,  (39) 
by  which  the  temperatures  above  600°  were  measured,  is 
calculated  to  be  equal  to  seven  of  Fahrenheit. 

50.  Cast  iron  3479°,  gold  2590°,  silver  2233°,  brass  1869°, 
antimony  810°,  zinc  648°,  lead  606°,  bismuth  497°,  tin 
442°,  sulphur  218°,  beeswax  142°,  spermaceti  112°,  phos- 
phorus 108°,  tallow  92°,  olive  oil  36°,  milk  30°,  blood  2.5°, 
sea  water  272°,  oil  of  turpentine  14°,  mercury — 39°,  nitric 
acid — 45^°,  sulphuric  ether — 46°. 

Exception  to  the  Law  that  Liquids  expand  by  Heat. 

51.  The  bulk  of  water  diminishes  with  the  temperature, 
until  it  reaches  39°  nearly.     Below  this  point,  it  expands 
as  it  grows  colder,  and  in  freezing  increases  in  bulk  one- 
ninth.     This  wonderful  exception  to  the  law  that  liquids 
expand  by  heat,  appears  to  be  a  special  provision  of  the 
Deity  for  the  preservation  of  aquatic  animals;  for  were 


10  IMPONDERABLE  SUBSTANCES. 

water  to  increase  in  density  as  it  approaches  the  point 
of  congelation,  the  upper  stratum  would  continue  to  sink 
as  refrigerated  in  bodies  of  water  below  39°,  as  well  as  in 
others.  Hence  a  whole  river,  lake,  or  sea  might,  in  high 
latitudes,  be  rendered  too  cold  for  animal  life;  and  finally 
be  so  far  converted  into  ice,  as  not  to  thaw  during  the 
ensuing  summer.  Subsequent  winters  co-operating,  the 
whole  might  be  consolidated  so  as  never  to  thaw.  But 
in  consequence  of  the  peculiarity  in  question,  the  cold- 
est stratum,  in  a  body  of  water  below  39°,  remains  at  top, 
until,  if  the  cold  be  adequate,  congelation  ensues.  The 
buoyant  sheet  of  ice,  which  results  in  this  case,  forms  effec- 
tively a  species  of  winter  clothing  to  the  water  beneath 
it;  and,  by  augmenting  with  the  frost,  opposes  an  increas- 
ing obstacle  to  the  escape  of  caloric  from  the  water  which 
it  covers. 

Expansion  of  Aeriform  Fluids. 

52.  Aeriform   fluids  are   much  more  expansible  than 
liquids.     In  order,  however,  to  appreciate  the  changes  of 
bulk  which  they  may  be  observed  to  sustain,  it  is  neces- 
sary to  understand  the  influence  which  the  pressure  of  the 
atmosphere  has  upon  their  density,  independently  of  tempe- 
rature.    The  simple  influence  of  heat,  in  expanding  them, 
may  be  illustrated  by  holding  a  hot  iron  over  the  thermo- 
meter of  Sanctorio,  represented  in  the  following  figure. 

Thermometers. 

53.  The  invention  of  the  thermometer  is  ascribed  to 
Sanctorio.     The  principle  of  that  form  of  the  instrument 
which  he  contrived  may  be  understood  from  the  following 
article. 


CALORIC. 


11 


Expansion  of  Air  illustrated  by  the  Air  Thermometer  of  Sanctorio  on 

a  large  Scale. 

54.  The  bulb  of  a  matrass  is  support- 
ed by  a  ring  and    an   upright  wire 
with  its  neck  downwards,    so  as  to 
have  its  orifice  beneath  the  surface  of 
the  water  in  a  small  glass  jar.     A 
heated  iron  being  held  over  the  ma- 
trass, the  contained  air  is  so  much  in- 
creasgd  in  bulk,  that,  the  vessel  being 
inadequate  to  hold  it,  a  partial  escape 
from  the   orifice   through   the  water 
ensues.     On  the  removal  of  the  hot 
iron,  the  residual  air  regains  its  pre- 
vious  temperature,    and  the   portion 
expelled  by  the  expansion  is  replaced 
by  the  water. 

55.  If  in  this  case  the  quantity  of  air 
expelled  be  so  regulated,  that  when 
the  remaining  portion  returns  to  its 
previous  temperature,  the  liquid  rises 
about  half  way  up  the  stem,  or  neck, 
the  apparatus  will  constitute  an  air 
thermometer.    For  whenever  the  tem- 
perature of  the  external  air  changes, 
the   air   in   the  bulb  of  the  matrass 

must,  by  acquiring  the  same  temperature,  sustain  a  corresponding  increase 
or  diminution  of  bulk,  and  consequently,  in  a  proportionate  degree,  influ- 
ence the  height  of  the  liquid  in  the  neck.  As  elastic  fluids  are  dilated 
equably,  in  proportion  to  the  temperature,  and  are  also  much  more  expan- 
sible than  liquids,  this  thermometer  would  be  very  accurate,  as  well  as 
pre-eminent  in  sensibility,  were  it  not  influenced  by  atmospheric  pressure 
as  well  as  temperature.  On  this  account,  however,  it  was  never  of  much 
utility.  Subsequently,  liquids  were  resorted  to,  and  the  instrument  assumed 
the  form  now  generally  employed,  the  principle  of  which  is  explained.  (45.) 

56.  In  the  following  pages  I  shall  give  engravings  and  descriptions  of 
the  form  of  the  thermometer  used  in  the  laboratory,  of  the  self- registering 
thermometer,  of  the  differential  thermometer,  and  of  an  apparatus  which 
illustrates  the  difference  between  it  and  Sanctorio's  thermometer. 

57.  Agreeably  to  the  example  of  my   predecessor  and  preceptor  Dr. 
Woodhouse,  I  have  been  accustomed  to  exhibit  to  my  class  the  blowing  and 
filling  of  a  thermometer.     Of  this  process  an  account  is  subjoined. 

58.  The  tubes  used  in  constructing  thermometers  are  made  at  almost  all  the  glass 
houses,  having  usually  a  capillary  perforation.     They  are  made  by  rapidly  drawing 
out  a  hollow  glass  globe  while  red-hot,  by  which  means  it  is  changed  into  a  long 
cylindrical  string  of  glass,  in  the  axis  of  which  a  perforation  exists,  in  consequence 
of  the  cavity  of  the  globe.     When  a  thermometer  tube  is  softened  by  exposure  to  a 
flame,  excited  by  a  blow-pipe,  a  bulb  may  be  blown  upon  it.    While  the  bulb  is  still 
warm,  the  other  end  of  the  tube  is  immersed  in  mercury,  or  in  spirit,  according  to 
the  purposes  for  which  the  instrument  is  intended.  As  the  bulb  cools,  the  air  within 
it  contracts,  and  thus  allows  the  liquid  to  enter,  in  obedience  to  the  pressure  of  the 
atmosphere.     The  bulb  thus  becomes  partially  supplied  with  the  liquid,  which  is 
next  boiled  in  order  to  expel  all  the  air  from  the  cavity  of  the  bulb  and  perforation. 


12  IMPONDERABLE  SUBSTANCES. 

The  orifice  being  again  depressed  into  the  liquid,  when  the  whole  becomes  cold  the 
liquid  will  fill  the  cavity  of  the  bulb.  This  result  will  be  hereafter  fully  explained 
and  illustrated.  The  open  end  of  the  tube  being  now  heated,  is  drawn  out  into  a 
filament  with  a  capillary  perforation.  The  bulb  being  raised  to  a  temperature  above 
the  intended  range  of  the  thermometer,  so  as  to  expel  all  the  superabundant  liquid, 
the  point  is  fused  so  as  to  seal  the  orifice  hermetically,  or  in  other  words  so  as  to  be 
perfectly  air-tight.  In  the  next  place,  the  bulb  is  to  be  exposed  to  freezing  water, 
and  the  point  to  which  the  liquid  reaches  in  the  capillary  perforation  marked.  In 
like  manner  the  boiling  point  is  determined,  by  subjecting  the  bulb  to  boiling  water. 
The  distance  between  the  freezing  and  boiling  points,  thus  ascertained,  may  be  di- 
vided according  to  the  desired  graduation. 

59.  The  scale  of  Reaumur  requires  80  divisions,  that  of  Celsius  100,  Fahrenheit's 
180.    The  graduation  of  Celsius  is  the  most  rational ;  that  of  Fahrenheit  the  least 
so,  although  universally  used  in  Great  Britain  and  the  United  States.     The  degrees 
of  these  scales  are  to  each  other  obviously,  as  80,  100,  and  180;  or  as  4,  5,  and  9. 
Hence  it  is  easy  to  convert  the  one  into  the  other  by  the  rule  of  three. 

60.  It  should,  however,  be  observed  that  the  scales  of  Celsius  and  Reaumur  com- 
mence at  the  freezing  of  water,  all  above  that  being  plus,  all  below  it  minus ;  while 
the  scale  of  Fahrenheit  commences  at  thirty-two  degrees  below  freezing.     Hence 
in  order  to  associate  correctly  any  temperature  noted  by  his  thermometer  with 
theirs,  we  must  ascertain  the  number  of  degrees  which  the  mercury  is  above  or 
below  freezing,  and  convert  this  number  into  one  equivalent  to  it  by  their  gradua- 
tion ;  and  conversely,  after  changing  any  number  of  degrees  of  theirs  into  his,  we 
must  consider  the  result  as  indicating  the  number  of  degrees  above  or  below  32  on 
his  scale. 

61.  The  process  above  described  for  the  construction  of  a  thermometer,  is  equally 
applicable  whether  the  bulb  be  filled  with  alcohol  or   mercury.     Each  of  these 
liquids  has  peculiar  advantages.     Mercury  expands  most  equably.     Equal  divisions 
on  the  scale  of  the  mercurial  thermometer  will  more  nearly  indicate  equal  incre- 
ments or  decrements  of  temperature.    Mercury  also  affords  a  more  extensive  range ; 
as  it  does  not  boil  below  656°,  nor  freeze  above— 39°,  of  Fahrenheit's  thermometric 
scale. 

62.  Alcohol,  being  more  expansible  than  mercury,  is  more  competent  to  detect 
slight  changes.     It  boils  at  176°  of  Fahrenheit,  and  for  its  congelation  is  alleged  to 
require — 90°  of  the  same  scale.     As  this  temperature  is  below  any  ever  observed  in 
nature,  and  can  only  be  attained  by  an  extremely  difficult  process,  latterly  disco- 
vered by  Bussier,  it  can  hardly  ever  happen  that  an  alcoholic  thermometer  will  not 
be  found  competent  to  measure  any  degree  of  cold  which  chemists  have  a  motive 
for  determining.     Besides  those  above  mentioned,  a  thermometric  scale  has  been 
used  in  Russia,  which  bears  the  name  of  its  author,  Delisle.     In  this,  zero  is  at  the 
boiling  point  of  water,  and  five  of  his  graduations  are  equal  to  six  of  Fahrenheit's. 


Laboratory  Thermometer. 

63.  The  thermometers  used  in  laboratories,  are  usually  con- 
structed so  as  to  have  a  portion  of  the  wood  or  metal,  which 
defends  them  from  injury  and  receives  the  graduation,  to 
move  upon  a  hinge,  as  represented  in  the  adjoining  figure. 

64.  This  enables  the  operator  to  plunge  the   bulb  into 
fluids,  without  introducing  the  wood  or  metal,  which  would 
often  be  detrimental  either  to  the  process  or  to  the  instru- 
ment, if  not  to  both. 

65.  The  scale  is  kept  straight  by  a  little  bolt  on  the  back 
of  it,  when  the  thermometer  is  not  in  use. 


Self-registering  Thermometer. 

O 


rrm  .  i  i  i  i  i  i  i  •  i  i  i  1 1  i  i 


J — I — I — I — 1 — L 


CALORIC. 


13 


66.  This  figure  represents  a  self-registering  thermometer.  It  comprises  necessarily  a 
mercurial  and  a  spirit  thermometer,  which  differ  from  those  ordinarily  used,  in  hav- 
ing their  stems  horizontal  and  their  bores  round ;  also  large  enough  to  admit  a  cylin- 
der of  enamel  in  the  bore  of  the  spirit  thermometer,  and  a  cylinder  of  steel  in  the  bore 
of  the  mercurial  thermometer.     Both  the  cylinder  of  enamel  and  that  of  steel  must 
be  as  nearly  of  the  same  diameter  with  the  perforations  in  which  they  are  respec- 
tively situated,  as  is  consistent  with  their  moving  freely  in  obedience  to  gravity,  or 
any  gentle  impulse. 

67.  In  order  to  prepare  the  instrument  for  use,  it  must  be  held  in  such  a  situation, 
as  that  the  enamel  may  subside  as  near  to  the  end  of  the  alcoholic  column  as  possible, 
yet  still  remaining  within  this  liquid.     The  steel  must  be  in  contact  with  the  mer- 
cury, but  not  at  all  immersed  in  it. 

68.  On  this  account  the  bulbs  of  the  thermometers  are  placed  at  opposite  ends  of  the 
plate  upon  which  they  are  secured ;  so  that  when  this  plate  is  made  to  stand  up  on 
one  end,  in  such  manner  as  to  have  the  bulb  of  the  mercurial  thermometer  lower- 
most, that  of  the  spirit  thermometer  will  be  uppermost.    Under  these  circumstances, 
impelled  by  gravity,  the  steel  cylinder  will  subside  upon  the  surface  of  the  mercurial 
column,  while  the  cylinder  of  enamel  will  sink  within  the  little  column  of  spirit, 
which  retains  it,  till  it  reaches  the  surface  of  that  column.     The  instrument  being, 
after  this  object  is  attained,  suspended  in  a  horizontal  position,  as  represented  in  the 
figure,  if  in  consequence  of  its  expansion  by  heat,  the  mercury  advance  into  the 
tube,  the  steel  moves  before  it;  but  should  the  mercury  "re  tire  during  the  absence  of 
the  observer,  the  steel  does  not  retire  with  it.     Hence,  the  maximum  of  temperature, 
in  the  interim,  is  discovered  by  noting  the  graduation  opposite  the  end  of  the  cylin- 
der nearest  the  mercury.     The  minimum  of  temperature  is  registered  by  the  enamel, 
which  retreats  with  the  alcohol  when  it  contracts,  but,  when  it  expands,  does  not 
advance  with  it.     The  enamel  must  retire  with  the  alcohol,  since  it  lies  at  its  mar- 
gin, and  cannot  remain  unmoved  in  the  absence  of  any  force  competent  to  extricate 
it  from  a  liquid,  towards  which  it  exercises  some  attraction.     But  when  an  opposite 
movement  lakes  place,  which  does  not  render  its  extrication  from  the  liquid  neces- 
sary to  its  being  stationary,  the  enamel  does  not  accompany  the  alcohol.     Hence  the 
minimum  of  temperature,  which  may  have  intervened  during  the  absence  of  the  ob- 
server, is  discovered  by  ascertaining  the  degree  opposite  the  end  of  the  enamel  near- 
est to  the  end  of  the  column  of  alcohol. 


Leslie's  Differential  Thermometer. 


o      o 


69  This  instrument  consists  of  a  glass  tube  nearly  in 
the  form  of  the  letter  U,  with  a  bulb  at  each  termination. 
In  the  bore  of  the  tube  there  is  some  liquid, as, for  instance, 
coloured  sulphuric  acid,  alcohol,  or  ether.  When  such 
an  instrument  is  exposed  to  any  general  alteration  of 
temperature  in  the  surrounding  medium,  as  in  the  case 
of  a  change  of  weather,  the  air  in  both  bulbs  being  equal- 
ly affected,  there  is  no  movement  produced  in  the  fluid; 
but  the  opposite  is  true,  when  the  slightest  change  of 
temperature  exclusively  affects  one  of  the  bulbs.  Any 
small  bodies  situated  at  different  places  in  the  same 
apartment  warmed  by  a  fire,  will  show  a  diversity  of 
temperature,  when  severally  applied  to  the  different 
bulbs. 


14 


IMPONDERABLE  SUBSTANCES. 


15 


Difference  between  an  Air  Thermometer  and  a  Differential  Thermometer,  illustrated 

upon  a  large  Scale. 

70.  The  adjoining  figure  represents 
an  instrument,  which  acts  as  an  air 
thermometer,  when  the  stopple  S  is 
removed  from  the  tubulure  in  the  coni- 
cal recipient,  R;  because  in  that  case, 
whenever  the  density  of  the  atmos- 
phere varies  either  from  changes  in 
temperature,  or  barometric  pressure, 
hereafter  to  be  explained,  the  extent 
of  the  alteration  will  be  indicated  by 
an  increase  or  diminution  of  the  space 
occupied  by  the  air  in  the  bulb,  B, 
and  of  course  by  a  corresponding 
movement  of  the  liquid  in  the  stem, 
T.  But  when  the  stopple  is  in  its  place, 
the  air  cannot,  within  either  cavity  of 
the  instrument,  be  affected  by  changes 
in  atmospheric  pressure :  nor  can 
changes  of  temperature  which  operate 
equally  on  botii  cavities,  produce  any 
movement  in  the  liquid  which  sepa- 
rates them.  Hence,  under  these  cir- 
cumstances, the  instrument  is  compe- 
tent to  act  only  as  a  differential  ther- 
mometer. 


MODIFICATION  OF  THE  EFFECTS  OF  CALORIC  BY  ATMOS- 
PHERIC PRESSURE. 

Digression  to  demonstrate  the  Nature  and  Extent  of  Atmospheric 

Pressure. 


Experimental  Proof  that  Air  has  Weight. 

71.  The  air  being  allowed  to  replenish  an 
exhausted  globe,  while  suspended  from  a  scale 
beam  and  accurately  counterpoised,  causes  it 
to  preponderate. 

72.  By  a  temporary  communication  with  an 
air  pump,  by  means  of  a  screw  with  which  it 
is  furnished,  a  glass  globe  is  exhausted  of  air. 
It  is  then  suspended  to  one  arm  of  a  scale  beam, 
and  accurately  counterpoised.     Being  thus  pre- 
pared, if  by  opening  the  cock  the  air  be  al- 
lowed to  re-enter  the  globe,  it  will  preponde- 
rate; and  if  a  quantity  of  water,  adequate  to 
restore  the  equilibrium,   be  introduced  into  a 
small  vessel,   duly   equipoised   by   a   counter- 
weight applied  to  the  other  arm  of  the  beam, 
the  inequality  in  bulk  of  equal  weights  of  air 
and  water  will  be  satisfactorily  exhibited. 


CALORIC. 


15 


Definition  of  Elasticity. 

73.  The  power  which  bodies  have  to  resume  their  shape,  position,  or 
bulk  on  the  cessation  of  constraint,  is  called  elasticity.     The  degree  in 
which  any  body  possesses  this  power  is  not  to  be  estimated  by  the  force, 
but  by  the  perfection  of  its  recoil.     A  coach  spring  is  far  more  powerful, 
but  is  not  more  elastic,  than  a  watch  spring. 

74.  Elasticity  is  erroneously  spoken  of  as  a  varying  property  in  the  air, 
which,  in  common  with  aeriform  fluids  in  general,  appears  to  be  always 
perfectly  elastic.  , 

75.  As  a  property  distinguishing  aeriform  fluids  from  liquids,  elasticity 
conveys  the  idea  of  a  power  in  a  given  weight  of  a  fluid  to  expand  or  to 
contract  with  the  space  in  which  it  may  be  confined,  producing  at  the  same 
time  a  pressure  on  the  internal  surface  of  the  cavity,  or  any  object  within 
it,  inversely  as  the  space. 

The  Existence  and  Extent  of  the  Pressure  of  the  Atmosphere  experimentally  demon- 
strated. 


PRELIMINARY  PROPOSITION. 

76.  For  the  pressure  of  any  fluid  on  any  area  assumed  within  it,  the  pressure  of  a  co- 
lumn of  any  other  fluid  may  be  substituted,  making  it  as  much  higher  as  lighter,  as 
much  lower  as  heavier;  or  in  other  words,  the  heights  are  inversely  as  the  gravities. 

Experimental  Illustration  in  the  case  of  Mercury  and  Water. 

77.  If  into  a  tall  glass  jar,  such 
as  is  represented  in  the  adjoining 
figure,  a  glass  cylinder,  C,  (like 
a  large  glass  tube  open  at  both 
ends)  were  introduced — on  filling 
the  jar  with  water,  this  liquid 
would  of  course  rise  in  the  cylin- 
der to  the  same  height  as  in  the 
jar;  but,  if,  as  in  the  figure,  be- 
fore introducing  the  water,  the 
bottom  of  the  jar  be  covered  with 
a  stratum  of  mercury,  two  inches 
deep,  so  as  to  be  sufficiently  above 
the  open  end  of  the  cylinder,  it 
must  be  evident  that  the  water 
will  be  prevented  from  entering 
the  cylinder  by  the  interposition 
of  a  heavier  liquid.  But  as  the 
pressure  of  the  water  on  the  mer- 
cury outside  of  the  cylinder  is 
unbalanced  by  any  pressure  from 
water  within  the  cylinder,  the 
mercury  within  will  rise,  until, 
by  its  weight,  the  external  pres- 
sure of  the  water  is  compensated. 
When  this  is  effected,  it  will  be 
seen,  on  comparing,  by  means  of 
the  scale,  S,  the  height  of  the 
two  liquids,  that  for  every  inch  of 
elevation  acquired  by  the  mer- 
cury, the  water  has  risen  more 
than  a  foot;  since  the  weight  of 
mercury  is  to  that  of  water,  as 
13.6  to  1. 


16 


IMPONDERABLE  SUBSTANCES. 


78.  It  may  be  demonstrated  that  the  pressure  of  the  column  of  mercury  is  exactly 
equivalent  to  that  of  a  column  of  water  having  the  same  base,  and  an  altitude 
equal  to  that  of  the  water  in  the  jar,  by  filling  the  cylinder  with  water.     It  will 
then  be  seen,  that,  when  the  water  inside  of  the  cylinder  is  on  a  level  with  the 
water  on  the  outside,  the  mercury  within  the  cylinder  is  also  on  a  level  with  the 
mercury  without. 

79.  It  is,  therefore,  obvious,  that  the  elevation  of  the  column  of  mercury,  within  the 
tube,  is  produced  by  the  weight  or  pressure  of  the  water  without,  and  measures  the 
extent  of  that  pressure  on  the  lower  orifice  of  the  tube. 

The  Illustration  extended  to  the  case  of  Liquids  lighter  than  Mercury. 

80.  Let  there  be  four  jars,  each  about  four  inches  in  diameter,  and  more  than  thirty 
inches  in  height,  severally  occupied  by  mercury  to  the  depth  of  about  two  inches. 
In  the  axis  of  each  jar,  let  a  tube  be  placed,  of  about  one  inch  and  a  half  in  diame- 
ter, and  about  one-fourth  taller  than  the  jar,  with  both  ends  open,  and  the  lower 
orifice  under  the  surface  of  the  mercury.     On  pouring  water  into  the  jars,  the  mer- 
cury rises  in  the  tubes,  as  the  water  rises  in  the  jars;  but  the  mercury  rises  as  much 
less  than  the  water  as  it  is  heavier. 

81.  The  mercurial  columns  in  this  case,  as  in  the  preceding  experiment,  owe  their 
existence  to  the  pressure  of  the  surrounding  water,  and  by  their  height  measure 
the  extent  of  that  pressure  on  the  areas  of  their  bases  respectively.     They  may  be 
considered  as  substituted  severally  for  the  aqueous  columns,  which  would  have  en- 
tered the  tubes  had  not  the  mercury  been  interposed.     Accordingly,  water  being 
poured  into  one  of  the  tubes,  the  mercury  in  that  tube  subsides  to  a  level  with  the 
mercury  without,  when  the  water  poured  into  the  tube  reaches  the  level  of  the 
water  without. 

82.  The  three  remaining  columns  of  mercury  may  be  considered  as  substituted, 
in  water,  for  columns  of  water,  and  being  as  much  lower  as  heavier  are  found  ade- 
quate to  preserve  the  equilibrium. 

83.  It  remains  to  be  proved  that  other  fluids,  heavier  or  lighter  than  water,  may  in 
like  manner  be  substituted  for  the  columns  of  mercury,  and  of  course  for  the  water  of 
which  the  mercury  is  the  representative. 


CALORIC. 


17 


84.  Into  the  three  tubes,  in  which,  by  the  addition  of  water  to  the  jars,  columns  of 
mercury  are  sustained,  pour  severally,  ether,  alcohol,  (differently  coloured,  so  that 
they  may  be  distinguished)  and  a  solution  of  sulphate  of  copper,  until  the  mercurial 
columns,  within  the  tubes,  are  reduced  to  a  level  with  the  mercury  without.     It 
will  be  found  that  the  column  formed  by  the  cupreous  solution  is  much  lower  than 
the  surface  of  the  water  on  the  outside  of  the  tube ;  that  the  opposite  is  true  of  the 
column  of  alcohol ;  and  that  the  ether,  still  more  than  the  alcohol,  exceeds  the  sur- 
rounding water  in  elevation. 

85.  While  it  is  thus  proved  that  columns  of  mercury,  ether,  alcohol,  and  of  a 
saline  liquid  may,  in  water,  be  substituted  for  columns  of  this  liquid;  it  is  also  appa- 
rent that  they  must  be  as  much  higher  as  lighter,  as  much  lower  as  heavier;  or  in 
other  words,  their  heights  must  be  inversely  as  their  gravities. 

Torricellian  Experiment. 

86.  Pursuant  to  the  law  which  has  been  above  illustrated,  that  the  pressure  of  one 
fluid  may  be  substituted  for  that  of  another,  provided  any  difference  of  weight  be 
compensated  by  a  corresponding  difference  in  height;  if,  in  lieu  of  water,  the  mer- 
cury were  pressed  by  air  on  the  outside  of  the  tubes,  unbalanced  by  air  within,  co- 
lumns of  the  metal  would  be  elevated,  which  would  be  in  proportion  to  the  height 
and  weight  of  the  air  thus  acting  upon  it. 

87.  In  order  to  show  that  the  air  exercises  a  pressure  on  the  mercury  outside  of 
the  tubes,  analogous  to  that  exercised  by  water  in  the  experiments  just  described,  it 
is  only  requisite  that  this  external  pressure  be  unbalanced  by  the  pressure  of  air 
within  the  tube.     This  desideratum  is  obtained  by  filling,  with  mercury,  a  tube 
about  three  feet  in  length,  open  at  one  end  and  closed  at  the  other,  and  covering  the 
open  end  with  the  hand,  until  it  be  inverted  and  merged  in  a  vessel  containing  some 
of  the  same  metal,  without  allowing  any  air  to  enter.     A  mercurial  column  of  about 
30  inches  in  height  will  remain  in  the  tube,  supported  by  the  pressure  of  the  sur- 
rounding air,  and  an  index  of  its  weight.     This  is  a  case  obviously  analogous  to 
that  of  the  mercurial  columns,  supported  by  the  pressure  of  water  in  the  experi- 
mental illustration  above  given. 

88.  The  tube  may  be  supposed 
to  occupy  either  of  the  three  posi- 
tions, represented  in  the  drawing. 
The  mercury,  in  each  position, 
preserves  the  same  degree  of  ele- 
vation, its  surface  being  always 
in  the  same  horizontal  plane,  or 
level,  whether  upright  or  inclined. 
Or  we  may  suppose  three  tubes, 
filled  with  mercury,  and  inverted 
in  a  vessel,  nearly  full,  of  the 
same  metal,  to  be  placed  in  the 
positions  represented  in  the  draw- 
ing. The  upper  surfaces  of  the 
columns  of  mercury  in  each  tube, 
will  be  found  always  coincident 
with  the  same  horizontal  plane, 
however  different  may  be  the  an- 
gle which  they  make  with  the 
horizon.  And  the  horizontal  plane, 
in  which  their  surfaces  are  thus 
found,  will  be  between  28  and  31 
inches  above  the  surface  of  the 
mercury  in  the  vessel.  The  line,  L, 
with  which  the  mercury  in  each  of 
the  tubes  is  on  a  level,  represents  a 
cord  rendered  horizontal,  by  mak- 
ing it  parallel  with  the  surface  of 
the  mercury  in  the  reservoir. 


18 


IMPONDERABLE  SUBSTANCES. 


Additional  Illustration  of  Atmospheric  Pressure. 

89.  I  trust  that  the  preceding  illustrations 
are  well  adapted  to  convey  a  clear  concep- 
tion of  atmospheric  pressure ;  but  as  it  some- 
times happens,  fortuitously,  that  when  truth 
cannot  get  access  to  the  mind   under  one 
form,  it  may  reach  it  in  another,  even  when 
less  eligible,  I  subjoin  the  following  illustra- 
tion, which,  though  less  amusing,  and  asso- 
ciating with  it  fewer  instructive  phenomena, 
is  more  brief,  and  perhaps  equally  conclu- 
sive. 

90.  If  a  tube,  recurved  into  a  crook  at  one 
end  so  as  to  form  a  syphon,  with  legs  of 
very  unequal  length,  and  both  ends  open, 
have  the  crook  lowered  into  water,  as  in  the 
adjoining  figure,  the  fluid  will  of  course, 
rise  within  the  tube  to  the  same  height  as 
without.     But  i'f,  before  the  crook  is  sunk 
in  the  fluid,  it  be  occupied  by  mercury,  the 
water  will  enter  the  tube,  only  so  far  as  the 
pressure  which  it  exerts  upon  the  mercury 
in  the  short  leg  of  the  syphon,  is  competent 
to  raise  the  mercury  in  the  long  leg. 

91.  This  pressure,  or  the  effort  of  the  water 
to  enter  the  tube,  is  obviously  measured  by 
the  height  to  which  it  forces  the  mercury, 
in  the  long  leg  of  the  syphon,  above  the 
mercurial  surface  in   the  short  leg.     The 
height  will  of  course  be  greater  or  less,  in 
proportion  to  the  depth  to  which  the  lower 
surface  of  the  mercury  may  be  sunk.     It 
will  also  be  greater  or  less,  according  as  the 
fluid  in  which  it  is  immersed  is  heavier  or 

lighter.     Hence,  as  water  is  about  820  times  heavier  than  air,  a  depth  of  820  inches 
in  air  would  displace  the  mercury  as  much  as  one  inch  in  water. 

92.  Let  us  imagine  a  tube  recurved  at  one  end,  similarly  to  the  one  represented 
in  the  foregoing  figure,  the  crook  likewise  occupied  by  mercury,  to  have  the  upper 
orifice  as  completely  above  the  atmpsphere,  as  the  orifice  of  the  tube  is  above  the 
water  in  the  jar.     The  mercury,  in  the  short  leg  of  the  syphon,  thus  situated,  would 
be  evidently  exposed  to  a  pressure,  caused  by  the  air  analogous  to  that  sustained 
from  water,  in  the  case  of  the  tube,  as  already  illustrated;  and  this  pressure  of  the 
air  would,  as  in  the  case  of  the  water,  be  measured  by  the  rise  of  the  mercury  in  the 
long  leg  of  the  syphon. 

93.  Yet  to  realize  this  experiment  with  a  syphon  reaching  above  the  atmosphere, 
it  is  obviously  impossible ;  but,  as  the  only  motive  for  giving  such  a  height  to  the 
syphon  is  to  render  the  mercury  in  the  long  leg  inacessible  to  atmospheric  pressure, 
if  this  object  can  be  otherwise  attained,  the  phenomenon  may  be  exhibited  in  the 
case  of  the  atmosphere  without  any  material  deviation. 

94.  In  fact,  to  protect  the  mercury  in  the  long  leg  from  atmospheric  pressure,  we 
have  only  to  seal  the  orifice  of  that  leg,  and,  through  the  orifice  of  the  other,  to  fill 
the  syphon  with  mercury,  before  we  place  it  in  a  vertical  position.     We  shall  then 
find  that  the  pressure  of  the  air  on  the  mercury,  in  the  open  leg  of  the  syphon,  will 
support  a  column  of  this  metal  in  the  other  leg  of  nearly  thirty  inches,  though  occa- 
sionally varying  from  28  to  31  inches. 

Inferences  respecting  the  Weight  of  the  Atmosphere  from  the  preceding  Experiments. 

95.  Supposing  the  base  of  the  column  of  mercury,  sustained  by  the  atmosphere, 
as  demonstrated  in  the  preceding  articles,  were  equivalent  to  a  square  inch,  the  total 
weight  of  the  column  would  be  about  fifteen  pounds.   This  of  course  represents  the 
weight  of  that  particular  column  of  air  only,  whose  place  it  has  usurped;  and  as, 
for  every  other  superficial  inch  on  the  earth's  surface,  a  like  column  of  air  exists, 
the  earth  must  sustain  a  pressure  from  the  "atmosphere,  equal  to  as  many  columns  of 
mercury,  30  inches  high,  as  could  stand  upon  it;  or  equal  to  a  stratum  of  mercury 
of  the  height  just  mentioned,  extending  all  over  the  surface  of  the  globe. 


CALORIC.  19 

96.  It  has  been  shown  that  the  heights  of  heterogeneous  fluids,  reciprocally  resist- 
ing  each  other,  are  inversely  as  their  gravities ;  or,  in  other  words,  that  they  are  as 
much  higher  as  lighter,  as  much  lower  as  heavier.     The  height  of  the  column  of 
air  which,  by  its  pressure,  elevates  the  mercury,  must,  therefore,  be  as  much  greater 
than  the  height  of  the  column  of  mercury,  as  the  weight  of  the  mercury  is  greater 
than  the  weight  of  the  air,  supposing  the  air  to  be  of  uniform  density.     Mercury  is 
11152  times  heavier  than  air,  and  of  course  the  height  of  the  atmosphere  would  be 
(if  uniform  in  density)  11152  X  30  inches  =  27880  feet;  supposing  30  inches  to  be 
the  height  of  the  mercurial  column  supported. 

97.  Hence  the  atmosphere,  if  of  the  same  density  throughout  as  on  the  surface  of 
the  earth,  would  not  extend  much  above  the  elevation  ascribed  to  the  highest  moun- 
tains. 

98.  But  as  the  pressure  of  the  atmosphere  causes  its  density,  it  may  be  demon, 
strated  that,  the  heights  increasing  in  arithmetical  progression,  the  densities  will 
decrease  in  geometrical  progression.     Thus  at  an  elevation  of  three  miles,  the  air 
being,  by  observation,  half  as  dense  as  upon  the  earth's  surface: 

At  6  miles  it  will  be  i  At  21  miles  it  will  be  T|T 

9     ....       I  24     ....     ^ 

12     ....      TV  27     -.          -      fa 

15     ....      7V  30     ...          „!„ 
18     ....      ,IT 

or  rarer  than  we  can  render  it  by  the  finest  air  pump.     These  results  have  been 
verified,  to  a  considerable  extent,  by  actual  observation. 

99.  It  is  reasonable  to  suppose  that  there  is  a  degree  of  rarefaction,  at  which  the 
weight  of  the  ponderable  particles  of  the  air  will  be  in  equilibrio  with  the  repulsive 
power  of  the  caloric  united  with  them.     Beyond  the  distance  from  the  earth's  sur- 
face at  which  there  should  be  such  an  equilibrium,  the  air  could  not  exist.     Hence 
it  is  inferred  that  the  extent  of  our  atmosphere  is  limited. 

Of  the  Water  Pump. 

100.  The  admission  of  the  atmosphere  is  necessary  to  the  suction  of  the  water 
from  a  receiver.  Air  may  be  removed  from  close  vessels  by  the  same  process.  Water 
rises  by  the  pressure  of  the  atmosphere  j  air  presses  out  by  its  own  elasticity. 

Mechanism  and  Action  of  the  Suction  Pump  rendered  evident  by  means  of  a  Model  with 
a  Glass  Chamber.  Difference  between  pumping  an  Elastic  Fluid  and  a  Liquid,  illus- 
trated by  an  appropriate  Contrivance. 

101.  A  little  suction  pump  is  constructed,  with  a  chamber  C  C,  of  glass,  which 
permits  the  action  of  its  piston,  P,  and  valves  to  be  seen.     Below  the  pump  is  a 
hollow  glass  globe  filled  with  water.     This  globe  communicates  with  the  pump  by  a 
tube,  visibly  descending  from  the  lower  part  of  the  pump,  through  an  aperture  in  the 
globe,  till  it  nearly  reaches  the  bottom.     This  tube  is  luted  air-tight  into  the  aper- 
ture by  which  it  enters  the  globe.     Its  orifice,  next  the  chamber,  is  covered  by  a 
valve  opening  upwards.    In  the  axis  of  the  piston  there  is  a  perforation,  also  covered 
by  a  valve  opening  upwards. 

102.  If  the  piston,  P,  be  moved  alternately  up  and  down  as  usual  in  pumping,  as 
often  as  it  rises  its  valve  will  shut  close  ;  so  that  if  nothing  passes  by  the  sides  of  the 
piston,  nor  enters  into  the  chamber  of  the  pump  from  below,  a  vacuum  must  be 
formed  behind  the  piston.     Under  these  circumstances,  it  might  be  expected  that 
the  water  would  rise  from  the  globe  through  the  lower  valve,  and  prevent  the  forma- 
tion of  a  vacuum.     But  being  devoid  of  elasticity,  and,  therefore,  incapable  of  self, 
extension  beyond  the  space  which  it  occupies,  the  water  does  not  rise  into  the  chain, 
ber  of  the  pump,  so  long  as  by  means  of  the  cock,  C,  of  the  recurved  pipe,  PP,  com. 
munication  with  the  external  air  is  prevented.     But  if  this  cock  be  opened  during 
the  alternate  movement  of  the  piston,  a  portion  of  the  water  will  mount  from  the 
globe  into  the  chamber  at  each  stroke  of  the  piston.     The  opening  of  the  cock  per- 
mits  the  atmosphere  to  press  upon  the  fluid  in  the  globe,  and  to  force  it  up  the  tube 
leading  to  the  pump  chamber,  as  often  as  the  chamber  is  relieved  from  atmospheric 
pressure  by  the  rise  of  the  piston.     As  soon  as  the  piston  descends,  the  valve  over 
the  orifice  of  the  tube  shuts,  and  prevents  the  water  from  returning  into  the  globe. 
It  is  of  course  forced  through  the  perforation  in  the  piston,  so  as  to  get  above  it. 


20 


IMPONDERABLE  SUBSTANCES. 


When  the  piston  rises,  the  valve  over  its  perforation  being  shut,  it  lifts  the  portion 
of  water  above  this  valve  until  it  runs  out  at  the  nozzle  of  the  pump;  while  the 
chamber,  below  the  piston,  receives  another  supply  from  the  globe.  But  if  after  all 
the  water  has  been  pumped  from  the  globe,  the  pumping  be  continued  with  the  cock 
closed ,  a  portion  of  air  will  be  removed  from  the  globe  at  each  stroke,  until  the  resi- 
due be  so  much  rarefied,  as,  by  its  elasticity,  no  longer  to  exert  against  the  valve, 
closing  the  tube,  sufficient  pressure  to  lift  it,  and  thus  to  expand  into  the  vacuity 
formed  behind  the  piston,  as  often  as  it  rises. 

103.  The  rarefaction  thus  effected  in  the  air  remaining  in  the  globe,  is  rendered 
strikingly  evident,  by  causing  the  orifice  of  the  curved  tube  to  be  under  the  surface 
of  some  water  in  an  adjoining  vase,  while  the  cock  is  opened.  The  water  rushes 
from  the  vase  into  the  exhausted  globe  with  great  violence  ;  and  the  extent  of  the 
rarefaction  is  demonstrated  by  the  smallness  of  the  space  within  the  globe  which  the 
residual  air  occupies,  after  it  is  restored  to  its  previous  density  by  the  entrance  of 
the  water. 


(Pago  21.) 


CALORIC.  21 


Description  of  a  Chemical  Implement. 

104.  The  operation  of  sucking  up  a  liquid  through  a  quill, 
arises  from  the  partial  removal  of  atmospheric  pressure  from 
within  the  quill  by  the  muscular  power  of  the  mouth.     There 
is  a  great  analogy  between  the  mode  in  which  suction  is  ef- 
fected by  the  mouth,  and  that  in  which  a  liquid  is  made  to  rise 
into  the  bulb  of  an  implement  which  I  am  about  to  describe, 
and  which  is  very  useful  for  withdrawing  small  portions  of 
liquids  from  situations  from  which  otherwise  they  cannot  be 
removed  without  inconvenience. 

105.  This  instrument  is  constructed  by  duly  attaching  a  bag 
of  caoutchouc  to  the  neck  of  a  glass  bulb  with  a  long  tapering 
perforated  stem. 

106.  In  order  to  withdraw  from  any  vessel  into  which  the 
stem  will  enter,  a  portion  of  any  contained  liquid,  it  is  only 
necessary  to  compress  the  bag  so  as  to  exclude  more  or  less  of 
the  air  from  within  it ;  then  to  place  the  orifice  of  the  stem  be- 
low the  surface  of  the  liquid,  and  allow  the  bag  to  resume  its 
shape.     Of  course,  the  space  within  it  becoming  larger,  the 
air  must  be  rarefied,  and  inadequate  to  resist  the  pressure  of 
the  atmosphere,  until  enough  of  the  liquid  shall  have  entered 
to  restore  the  equilibrium  of  density  between  the  air  within 
the  bag  and  the  atmosphere.     The  air  within  the  bag  cannot, 
however,  fully  resume  its  previous  density ;  since  the  column 
of  the  liquid  counteracts,  as  far  as  it  goes,  the  atmospheric 
pressure.     Indeed,  this  counteracting  influence  is  so  great  in 
the  case  of  mercury,  that  the  instrument  cannot  be  used  with 

this  liquid.  It  is  however  the  only  substance,  fluid  at  ordinary  temperatures,  which 
is  too  heavy  to  be  drawn  up  into  the  bulb  of  the  instrument  in  question,  when  fur- 
nished with  a  stout  bag. 

Of  the  Mr  Pump. 
Difference  between  the  Mr  Pump  and  the  Water  Pump. 

107.  The  action  of  the  air  pump  is  perfectly  analogous  to  that  of  the  water  pump;  as 
there  is  no  difference  between  pumping  water  and  pumping  air,  excepting  that  which 
arises  from  the  nature  of  the  fluids;  the  one  being  elastic,  the  other,  in  common  with 
liquids  in  general,  almost  destitute  of  elasticity. 

108.  In  the  air  pump,  as  in  the  water  pump,  therefore,  there  is  a  chamber,  and  an 
upper  and  lower  valve,  which  operate  in  the  same  manner  as  the  valves  of  the  water 
pump  already  described. 

Description  of  a  large  Mr  Pump  with  Glass  Chambers. 

109.  The  opposite  engraving  represents  a  very  fine  instrument  of  large  size,  ob- 
tained  from  Mr.  Pixii,  of  Paris. 

110.  From  the  figure,  it  must  be  evident  that  this  pump  has  two  glass  chambers. 
They  are    unusually  large,   being  nearly  three   inches   in   diameter   inside.     The 
lower  valvB,  V,  is  placed  at  the  end  of  a  rod,  which  passes  through  the  packing  of 
the  piston.     Hence,  during  the  descent  of  the  piston,  the  friction  of  the  packing 
against  the  rod,  causes  it  to  act  upon  the  valve  with  a  degree  of  pressure  adequate 
to  prevent  anv  escape  of  air,  through  the  hole  which  it  closes,  at  the  bottom  of  the 
chamber.     The  air  included  between  the  piston  and  the  bottom  of  the  chamber,  is, 
therefore,  by  the  descent  of  the  piston,  propelled  through  a  channel  in  the  axis  of  the 
piston,  covered  by  a  valve  opening  upwards.     When  the  motion  of  the  piston  is  re- 
versed, the  air  cannot,  on  account  of  the  last  mentioned  valve,  return  again  into  the 
cavity  which  the  piston  leaves  behind  it.     But  in  the  interim,  the  same  friction  of 
the  packing,  about  the  rod,  which  had  caused  it  to  press  downwards,  has  now,  in 
consequence  of  the  reversal  of  the  stroke,  an  opposite  effect,  and  the  valve  V  is  lifted 
as  far  as  a  collar  on  the  upper  part  of  the  rod  will  permit.    The  rise,  thus  permitted, 
is  just  sufficient  to  allow  the  air  to  enter  the  chamber  through  an  aperture  which  the 
valve  had  closed,  and  which  communicates  by  means  of  a  perforation  with  a  hole  in 
the  centre  of  the  air  pump  plate,  and  of  course  with  the  cavity  of  the  receiver,  RR, 
placed  over  the  plate.     The  reaction  of  the  air  in  the  perforation  and  pump  chamber 


22 


IMPONDERABLE  SUBSTANCES. 


being  diminished,  the  air  of  the  receiver  moves  into  the  chamber  until  the  equili- 
brium of  density  is  restored  between  the  two  cavities.  The  chamber  will  now  be  as 
full  of  air  as  at  first;  but  the  air  with  which  it  is  replenished  is  not  so  dense  as  before, 
as  the  whole  quantity  in  the  receiver  and  the  chamber  scarcely  exceeds  that  which 
had  existed,  before  the  stroke,  in  the  receiver  alone.  By  the  next  downward  stroke, 
the  air  which  has  thus  entered  the  chamber  is  propelled  through  the  valve  hole  in 
the  piston.  Another  upward  stroke  expels  this  air  from  the  upper  portion  of  the 
chamber;  and  the  valve  attached  to  the  rod  being  again  uplifted,  the  portion  of  the 
chamber,  left  below  the  piston,  is  supplied  with  another  complement  of  air  from  the 
receiver :  and  thus  a  like  bulk  of  air  is  withdrawn  at  every  stroke  of  the  pump.  I 
say  a  like  bulk  of  air,  since  the  quantity  necessarily  varies  with  the  density  of  the  air 
in  the  vessel  subjected  to  exhaustion.  This  density  is  always  directly  as  the  quantity 
of  air  remaining ;  of  course  it  finally  becomes  insignificant.  Thus  when  the  quantity, 
in  the  receiver,  is  reduced  to  one-hundredth  of  what  it  was  at  first,  the  weight  of  air 
removed,  at  each  stroke,  will  be  one-hundredth  of  the  quantity  taken  at  each  stroke 
when  the  process  began. 

111.  I  have  explained  the  action  of  one  chamber  only,  as  that  of  the  other  is  ex- 
actly similar,  excepting  that  while  the  piston  of  one  descends,  that  of  the  other 
rises. 

112.  The  gauge  represented  in  the  engraving,  is  one  which  I  have  contrived  upon 
a  well  known  principle.     It  consists  of  a  globular  vessel  to  hold  mercury,  supported 
upon  a  cock.     The  mercury  is  prevented  from  entering  the  perforation  in  the  cock, 
by  a  tube  of  iron,  surmounted  by  a  smaller  one  of  varnished  copper,  which  passes  up 
into  a  Torricellian  glass  tube  till  it  reaches  near  the  top.     The  glass  tube  opens  at 
its  lower  extremity,  under  the  surface  of  the  mercury  in  the  globe.     The  exhaustion 
of  this  tube,  and  that  of  any  vessel  placed  over  the  air  pump  plate,  proceed  simulta- 
neously, and  consequently  the  mercury  is  forced  up  from  the  globe  into  the  glass 
tube  to  an  altitude  commensurate  with  the  rarefaction. 

113.  By  inspecting  a  scale,  SS,  behind  the  glass  tube,  the  height  of  the  mercury 
is  ascertained.     In  order  to  make  an  accurate  observation,  the  commencement  of 
the  scale  must  be  duly  adjusted  to  the  surface  of  the  mercury  in  the  globe.     On  this 
account  it  is  supported  by  sliding  bands  on  an  upright  square  bar,  between  the  glass 
cylinders. 

114.  The  receiver,  RR,  represented  on  the  air  pump  plate,  is  one  which  I  usually 
employ  in  exhibiting  the  artificial  aurora  borealis.     The  sliding  wire,  terminated  by 
a  ball,  enables  the  operator  to  vary  the  distance  through  which  the  electrical  corus- 
cations are  induced. 

Experimental  Illustrations  of  the  Elastic  Reaction  of  the  Mr. 
Air  occupying  a  small  Portion  of  a  Cavity,  rarefied  so  as  to  fill  the  whole  Space. 

115.  Air  is  dependent  on  its  own  weight  for  its  density,  and  enlarges  in  bulk  in 
proportion  as  the  space  allotted  to  it  is  enlarged. 

116.  The  mode  in  which  the  air  occupying  but  a  small 
part  of  a  vessel  may  be  rarefied  so  as  to  fill  the  whole 
cavity,  is  shown  by  the  experiment  represented  in  the 
annexed  engraving.     A  bladder  is  so  suspended  within 
a  vessel  included  in  a  receiver,  as  that  the  cavity  of  the 
bladder  communicates  through  its  own  neck  and  that  of 
the  vessel,  with  the  cavity  of  the  receiver;  while  no 
such  communication  exists  between  the  receiver  and 
the  space  between  the  bladder  and  the  inside  of  the 
vessel. 

117.  Things  being  thus  situated,  and  the  receiver  ex- 
hausted, the  bladder  contracts  in  consequence  of  the 
removal  of  air  from '  within  it,  proportionably  with  the 
exhaustion  of  the  receiver ;  for,  as  the  air  between  the 
outside  of  the  bladder,  and  the  inside  of  the  vessel,  is 
no  longer  resisted,  within  the  bladder,  by  air  of  the  same 
density,  it  expands  into  the  space  which  the  bladder 
had   occupied,  so  as  to  reduce  it  into  a  very  narrow 
compass. 

118.  This  cannot  excite  surprise,  when  it  is  recollected 
that  the  air,  confined  between  the  outside  of  the  blad- 
der and  the  inside  of  the  vessel,  had  previously  to  the  exhaustion  been  condensed  by 
supporting  the  whole  atmospheric  pressure,  and  must  of  course  enlarge  itself  from 
its  elasticity,  as  that  pressure  is  diminished. 


CALORIC. 


23 


Distcntion  of  a  Caoutchouc  Bag  by  the  Rarefaction  of  confined  Mr. 

119.  The  power  of  any  included  portion  of  air  to  ex- 
tend itself  in  consequence  of  a  removal  of  pressure, 
is  illustrated  in  another  way,  by  subjecting  to  a  highly 
rarefied  medium  a  gum  elastic  bag,  its  orifice  being 
previously  closed,  so  as  to  be  air-tight.     The  bag  will 
swell  up  in  a  most  striking  manner,  in  proportion  to 
the  diminution  of  power  in  the  air  without  the  bag  to 
counteract  the  reaction  of  the  air  within  it. 

120.  The  experiment  is  reversed  by  subjecting  a 
bag,  while  inflated,  to  the  influence  of  a  condenser, 
by  which  it  may  be  reduced  in  size  more  than  it  had 
been  expanded;   the  air  within  the  receiver  being 
rendered  denser  than  without. 

121.  In  the  adjoining  cut,  the  gum  elastic  bag  is  re- 
presented as  when  inflated.     The  glass  represented 
below  the  bag,  is  one  which  happened  to  be  used  as  a 
support  when  the  drawing  was  made. 


Expulsion  of  a  Liquid  by  the  Rarefaction  of  Mr. 
122.  A  flask,  half  full  of  water,  is  inverted  in  another 
vessel,  having  some  water  at  the  bottom,  and  both  are 
placed,  under  a  bell  glass,  on  the  plate  of  an  air  pump. 
As  the  bell  is  exhausted  by  the  action  of  the  pump,  the 
air  included  in  the  flask  enlarges  its  bulk,  finally  occu- 
pying the  whole  cavity,  and  partially  escaping  from  the 
orifice  through  the  water  in  the  lower  vessel.  When 
the  atmosphere  is  allowed  to  re-enter  the  bell,  the  water 
rises  into  the  flask,  so  as  to  occupy  as  much  more  space 
than  at  first,  as  the  air  occupies  less,  in  consequence  of  a 
portion  having  escaped  as  abovementioned. 


Experimental  Proofs  of  the  Weight  of  the  Atmosphere. 

Atmospheric  Pressure  on  the  Hand. 
123.  If,  as  represented  in  this  figure,  the  air  be  ex- 
hausted from  a  vessel  covered  by  the  hand,  its  re- 
moval will  be  found  almost  impracticable :  for,  sup- 
posing the  opening  which  the  hand  closes  to  be  equal 
to  five  square  inches,  at  15  Ib.  per  square  inch,  the 
pressure  on  it  will  evidently  be  seventy-five  pounds. 


Bladder  ruptured  by  the  Weight  of  the  Atmosphere. 

124.  Let  there  be  a  glass  vessel  open  at  both  ends, 
as  represented  in  this  figure.  Over  the  upper  opening 
let  a  bladder  be  stretched  and  tied,  so  as  to  produce  an 
air-tight  juncture.  For  every  square  inch  of  its  super- 
ficies, the  bladder  thus  covering  the  opening  in  the 
vessel  sustains  a  pressure  of  about  15  pounds.  Yet 
this  is  productive  of  no  perceptible  effect;  because  the 
atmosphere  presses  upwards  against  the  lower  surface 
of  the  bladder,  as  much  as  downwards  upon  the  upper 
surface.  But  if  the  vessel  be  placed  upon  the  plate 
of  an  air  pump,  so  that,  by  exhaustion,  the  atmosphe- 


24 


IMPONDERABLE  SUBSTANCES. 


tic  pressure  downwards  be  no  longer  counteracted  by  its  pressure  upwards,  the  blad- 
der will  be  excessively  strained,  and  usually  torn  into  pieces. 

125.  When  the  bladder  is  too  strong  to  be  broken  by  the  unassisted  weight  of  the 
air,  a  slight  score  with  the  point  of  a  penknife  will  cause  it  to  be  ruptured  not  only 
where  the  score  is  made,  but  in  various  other  parts,  so  that  it  will,  at  times,  be  torn 
entirely  from  the  rim  of  the  vessel. 


R 


The  Hemispheres  of  Otho  Gueriche,  the  celebrated  Inventor  of  the  Air  Pump. 

126.  Two  brass  hemispheres 
are  so  ground  to  fit  each  other 
at  their  rims  as  to  form  an  air- 
tight sphere  when  united.  One 
of  the  hemispheres  is  furnished 
with  a  cock,  on  which  is  a 
screw  for  attaching  the  whole 
to  the  air  pump.  Being  by 
these  means  exhausted,  the  cock  closed,  and  the  ring,  R,  screwed  on  to  the  cock, 
great  force  must  be  exerted,  before  the  hemispheres  can  be  separated. 


Bottle  broken  by  Exhaustion  of  the  Mr  from 
within. 

127.  Proof  that  a  square  glass  bottle  may  be  broken 
by  atmospheric  pressure  on  the  outside,  as  soon  as  it 
ceases  to  be  counteracted  by  the  resistance  of  the  air 
within. 

128.  The  mouth  of  a  square  bottle  being  placed 
over  the  hole  in  an  air  pump  plate,  so  as  to  be  suffi- 
ciently tight  for  exhaustion,  a  few  strokes  of  the 
air  pump,  by  withdrawing  the  air  from  the  interior, 
causes  the  bottle  to  be  crushed. 

129.  A  stout  globular  glass  vessel,  with  an  aper- 
ture at  top,  is  placed  over  the  bottle,  to  secure  the 
spectators  from  the  fragments. 


Bottle  broken  by  Exhaustion  of  the  Mr  from 
without. 

130.  The  elastic  reaction  of  the  air,  confined  within 
a  square  bottle,  will  burst  it,  as  soon  as  relieved  from 
the  counteracting  weight  of  the  atmosphere. 

131.  If  a  thin  square  bottle,  so  sealed  that  while 
unbroken  the  contained  air  cannot  escape,  be  placed 
within  the  receiver  of  an  air  pump,  the  exhaustion 
of  the   receiver   will,   by   removing    the    pressure 
which  counteracts  the  elastic  reaction  of  the  con- 
fined air,  cause  the  bottle  to  be  fractured. 


The  Height  of  the  Column  of  Mercury  which  balances  the  Atmosphere,  shown  by 

Exhaustion. 

132.  R,  fig.  1,  is  a  hollow  glass  cylinder,  about  33  inches  in  height,  and  2£  inches 
in  diameter,  into  the  upper  end  of  which  a  brass  gallows  screw,  G,  is  cemented;  so 
that  by  means  of  the  flexible  pipe  communicating  with  the  air  pump  plate,  A,  the 
cylinder  may  be  exhausted.  The  mouth  of  the  cylinder  being  immersed  in  mercury 
in  the  vase,  the  metal,  as  the  exhaustion  proceeds,  rises  in  the  cylinder,  until  it 


CALORIC.  Zb 

reaches  more  or  less  nearly  to  the  height  at  which  it  slando  in  a  Torricellian  tube, 
accordingly  as  the  pump  may  be  more  or  less  perfect. 

FIG.  2. 
FIG.  1. 


Barometric  Column  of  Mercury  lowered  by  Exhaustion. 

133.  It  has  been  shown  that  in  a  tube  void  of  air,  a  mercurial  column  may  be  sup- 
ported at  the  height  nearly  of  thirty  inches;  and  this  has  been  alleged  to  result 
from  the  pressure  of  the  atmosphere  on  the  surface  of  the  mercury  on  the  outside  of 
the  tube. 

134.  In  order  to  verify  this  allegation,  let  a  tube,  fig.  2,  supporting  within  it  a 
column  of  mercury,  be  placed  under  a  competent  receiver  upon  the  air  pump  plate. 

135.  It  will  be  found  that,  as  the  air  is  withdrawn  from  the  receiver,  the  mercury 
in  the  tube  will  subside,  and,  if  the  exhaustion  be  carried  far  enough,  will  sink  to  a 
level  with  the  mercury  on  the  outside. 

136.  If,  while  this  experiment  is  performing,  a  communication  exist  between  the 
air  pump  and  the  cylinder,  R,  employed  in  the  preceding  experiment,  the  mercury 
will  rise  in  the  cylinder,  while  it  falls  in  the  tube ;  thus  proving  that  the  force  which 
is  required  to  remove  the  air  from  the  outside  of  the  tube  and  lower  the  mercury 
within  it,  is  adequate  to  raise  in  the  cylinder  a  mercurial  column  equal  in  height  to 
that  which  is  reduced. 


IMPONDERABLE  SUBSTANCES. 


Of  the  Barometer  Gauge. 

137.  While  I  am  upon  the'  subject  of  atmospheric 
pressure,  it  appears  to  me  expedient  to  give  a  de- 
scription of  an  instrument  which,  in  several  of  my 
illustrations,  is  employed  to  ascertain  the  quantity 
of  air  within  a  receiver. 

138.  It  consists  of  a  barometer  tube,  33  inches  in 
height,  supported  in  a  vertical  position  by  a  pedes- 
tal, and  a  strip  of  wood,  G-  G.     Attached   to  the 
latter  is  a  brass  scale,  by  which  30  inches  is  divided 
into  500  equal  parts.  The  gauge  tube  is  surmounted 
by  a  ferrule  and  gallows  screw,  by  the  aid  of  which 
a  flexible  leaden  pipe,  P,  communicates  with  the 
bore  of  the  tube.     By  means  of  the  valve  cock  and 
gallows  screw  at  V,  this  pipe  may  be  made  to  com- 
municate also  with  the  cavity  to  be  measured,  the 
valve  cock  enabling  us  to  suspend  the  communica- 
tion when  desirable.    The  lower  orifice  of  the  glass 
tube,  T,  is  covered  by  mercury  in  a  broad  shallow 

'  receptacle,  D.  Supposing  the  cavity,  under  these 
circumstances,  to  be  exhausted,  and  the  communi- 
cation with  the  bore  of  the  glass  tube  open,  the  ex- 
tent of  the  exhaustion,  or,  in  other  words,  the 
quantity  of  air  withdrawn,  will 'be  exactly  in  pro- 
portion to  the  rise  of  the  mercury  as  indicated  by 
the  scale;  and  consequently,  reversing  the  operation, 
the  fall  of  the  mercury,  as  indicated  by  the  scale, 
will  show  the  quantity  of  air  which  may  be  intro- 
duced. If  we  count  the  degrees  upwards  from  the 
surface  of  the  mercury  in  the  receptacle,  D,  their 
number  will  show  the  quantity  of  air  withdrawn. 
If  we  count  the  degrees  downwards  from  the  level 
of  the  top  of  the  mercurial  column  in  the  barometer, 
the  number  will  indicate  the  exact  quantity  of  gas 
in  the  cavity  examined.  In  short,  the  quantity  taken 
out,  or  introduced,  is  always  measured  by  the  num- 
ber of  degrees  which  the  mercury  rises  or  falls  in 

consequence.     It  is  preferable  to  have  two  scales,  one  beginning  above,  the  other 

below. 

139.  This  gauge  may  be  employed  to  indicate  the  quantity  of  air  in  any  cavity. 
It  only  requires  accuracy  in  the  divisions  of  the  scale,  and  in  the  adjustment  of  zero 
to  the  proper  level.     As  the  height  of  the  mercurial  column  in  the  barometer  varies 
with  those  changes  of  atmospheric  pressure  which  it  is  employed  to  indicate,  there- 
fore, in  counting  downwards,  care  must  be  taken  to  place  the  commencement  of  the 
scale  on  a  level  with  the  upper  end  of  a  column  of  mercury  in  a  good  barometer,  at 
the  time.     To  facilitate  this  adjustment,  I  have  occasionally  placed  a  Torricellian 
tube  by  the  side  of  the  gauge  tube.     The  top  of  the  column  of  the  mercury  in  the 
Torricellian  tube  is  then  the  proper  point  for  the  upper  zero.     As  the  strip  of  wood 
to  which  the  scale  is  attached  slides  upon  the  iron  rod,  R,  the  scale  may  be  fixed  at 
a  proper  height  by  a  set  screw.* 

140.  As  a  perfect  vacuum  cannot  be  produced  by  means  of  an  air  pump,  in  order 
to  wash  out  of  a  receiver  all  traces  of  atmospheric  air,  it  is  necessary  that  portions 
of  the  gas  to  be  substituted  should  be  repeatedly  introduced,  and  as  often  removed 
by  exhaustion.! 

141.  The  rise  of  the  mercury  in  the  tube,  by  diminishing  the  quantity  in  the  re- 
ceptacle, D,  will  cause  the  surface  of  it  to  be  lower;  but  the  breadth  of  this  vessel 
is  so  great,  and  the  descent  of  the  mercurial  surface  in  it  so  inconsiderable,  that  no 
error  worthy  of  attention  is  thus  produced. 

142.  It  is  proper  to  mention  that  the  cavity  of  the  tube  ought  to  be  so  small  in 
proportion  to  that  of  the  receiver,  as  to  create  no  error  worthy  of  attention. 


*  Both  the  gauge  tube  and  the  rod,  R,  should  be  longer  than  they  are  represented 
in  the  figure. 

t  One  gas  may  be  employed  to  wash  another  out  of  a  cavity,  in  a  mode  analogous 
to  that  in  which  water  may  wash  out  alcohol,  or  alcohol  water. 


CALORIC.  27 

Apparatus  for  illustrating  the  Difference  between  the  Lifting  and  Forcing  Pumps. 


143.  The  process  by  which  the  water  is  drawn  into  the  chamber  is  the  same  in 
the  case  of  the  forcing  as  in  that  of  the  lifting  pump.     In  the  lifting  pump,  L,  the 
water  which  has  entered  the  chamber  during  the  ascent  of  the  piston,  passes  through 
the  piston  during  its  descent,  and  is  lifted  by  it  when  the  motion  is  reversed.  In  the 
forcing  pump,  F,  the  piston,  being  imperforate,  forces,  in  descending,  the  water  into 
the  adjoining  air  vessel,  A,  whence  its  regress  is  prevented  by  a  valve,  V,     The 
stroke  being  repeated,  the  water  accumulates  in  the  air  vessel,  compressing  the  con- 
tained air,  until  it  reacts  upon  the  water  with  sufficient  force  to  cause  an  emission  of 
this  liquid  through  the  jet  pipe,  J  J,  commensurate  with  the  supply. 

Of  Condensation. 

144.  It  has  been  shown  that,  in  consequence  of  the  elasticity  of  the  air,  the  quan- 
tity of  this  fluid,  in  any  close  vessel,  may  be  diminished  until  the  residual  portion 
has,  by  the  action  of  the  air  pump,  become  too  rare  to  escape  in  opposition  to  the 
very  slight  resistance  made  by  the  valves.     It  remains  to  show  that,  in  consequence 
of  the  same  property,  by  an  operation  the  converse  of  that  of  the  air  pump,  the  air 
in  any  adequate  vessel  may  be  made  many  times  more  dense  than  it  would  other- 
wise be. 

Of  the  Condenser. 

145.  The  instrument  employed  for  the  purpose  of  condensing  air  is  called  a  con- 
denser. 

146.  The  air  pump  was  illustrated  by  its  analogy  with  the  suction  pump.     There 
is  the  same  analogy  between  the  condenser  and  the  forcing  pump.     In  the  air  pump, 
the  valve  between  the  chamber  and  receiver  opens  towards  the  chamber;  in  the  case 
of  the  condenser  a  corresponding  valve  opens  towards  the  receiver. 

147.  Besides  the  valve  thus  placed  between  the  chamber  and  receiver,  there  is  in 
each  pump  another  valve.     In  the  air  pump,  the  air  passes  this  second  valve  only 


IMPONDERABLE  SUBSTANCES. 


when  the  piston  moves  so  as  to  lessen  the  vacancy  between  it  and  the  bottom  of  the 
chamber ;  in  the  condenser,  the  air  passes  only  when  the  piston  moves  so  as  to  en- 
large the  vacancy.  In  other  respects  these  machines  are  so  much  alike,  that  the  one 
might  be  used  for  the  other.  In  my  experimental  illustrations,  I  shall  have  occasion 
to  employ  instruments  which  serve  either  to  exhaust  or  to  condense,  according  to 
the  aperture  selected  for  making  a  communication  with  the  receiver. 

FIG.  1. 

'.  148.  Fig.  1,  in  the  adjoining  engraving, 
represents  a  condenser.  It  consists  of  a 
brass  cylinder,  A  A,  ground  internally,  so 
as  to  be  perfectly  cylindrical.  Into  this 
a  piston,  B,  is  fitted  by  means  of  oiled 
leathers  packed  between  screws,  repre- 
sented in  the  figure,  and  turned  in  the 
lathe,  so  as  to  enter  the  chamber  in  obedi- 
ence to  considerable  force.  At  the  lower 
end  of  the  rod,  a  perforation,  C  C,  may  be 
seen,  which  commences  at  the  lower  ex- 
tremity, rises  vertically  until  it  gets  above 
the  packing,  and  then  passes  out  at  right 
angles  to  its  previous  direction  through  the 
rod  of  the  piston.  Just  above  where  it 
commences,  a  cavity,  D,  may  be  observed, 
which  is  left  for  the  upper  valve.  This 
valve  is  formed  of  a  strip  of  oiled  leather 
tied  over  a  brass  knob  represented  within 
the  cavity. 

149.  The  upper  and  lower  valves  are  ex- 
actly alike;  hence,   a  good  idea  of  either 
may  be  obtained  from  fig.  2,  which  affords 
a  separate  view  of  the  lower  valve. 

150.  The  action  of  the  condenser  is  as 
follows.     When  the  piston  is  drawn  up,  all 
the  air  within  the  chamber  gets  below  the 
packing  through  the  perforation,  C  C,  and 
the  upper  valve,  which  opens  downwards 
with  ease  so  as  to  afford  a  passage.     When 
the  piston  descends,  the  air  included  in  the 
chamber  cannot  get  by  the  leather  packing. 

The  upper  valve  at  the  same  time  shuts  so  as  to  prevent  it  from  getting  through  the 
perforation,  C  C.  It  has  therefore  to  proceed  through  the  lower  perforation,  E. 
The  piston  being  drawn  up  again,  the  valve  at  E  shuts  and  prevents  a  return  of  the 
air  expelled,  while  the  air  of  the  chamber  again  gets  below  the  piston  as  in  the  first 
instance.  Thus,  at  every  stroke,  the  contents  of  the  chamber  are  discharged  through 
the  lower  valve,  while  its  retrocession  from  any  receiver  into  which  it  may  pass  is 
prevented  by  the  valve,  E. 

151.  As  the  quantity  of  air  in  the  vessel  increases,  the  force  requisite  to  drive  the 
piston  home  becomes  greater ;  and  it  has  to  descend  farther,  ere  the  air  within  the 
chamber  exceeds  in  density  that  in  the  receiver,  so  far  as  to  open  the  lower  valve. 

Influence  of  Pressure  on  the  Bulk  of  Mr,  and  of  its  Density  on  its  Resistance. 

152.  Mr  lessens  in  bulk  as  the  pressure  which  it  sustains  augments ;  and  the  resist- 
ance arising  from  its  elasticity  is  augmented,  as. the  quantity  confined  in  the  same  space 
is  increased,  or  the  confining  space  diminished. 

153.  For  the  illustration  of  this  proposition,  I  have  devised  the  apparatus  repre- 
sented in  the  opposite  engraving. 

154.  If  mercury  bo  poured  into  the  air-tight  vessel,  A,  through  the  tube,  T  T, 
which  passes  perpendicularly  into  this  vessel  until  it  touches  the  bottom ;  as  the  air 
in  the  vessel  cannot  escape,  it  is  gradually  reduced  in  bulk,  but  at  the  same  time  re- 
acts upon  the  surface  of  the  metallic  liquid  with  a  force  which  becomes  greater,  in 
proportion  as  its  bulk  is  lessened.     Hence  an  increasing  mercurial  column  will  be 
upheld,  which  by  its  height  indicates  the  resistance.     When  the  air  in  the  vessel 
has  been  reduced  to  half  its  previous  bulk,  the  height  of  the  mercury  in  the  tube  will 
be  about  '.50  inches,  or  equal  to  that  of  the  mercury  in  the  barometer  at  the  time  of 


Apparatus  for  illustrating  the  Influence,  of  Pressure  on  the  Bulk  of  Air. 


T 


(Page  28.) 


CALORIC.  4\) 

performing  the  experiment.  Thus  it  is  shown,  that  when  air  is  condensed  into  half 
the  space  which  it  occupies  under  the  pressure  of  the  atmosphere,  its  reactive  power 
is  doubled,  being  adequate  to  support  a  column  of  mercury  equal  to  the  pressure  of 
the  Atmosphere,  in  addition  to  that  pressure.  It  follows  that  the  quantity  of  air  oc- 
cupying any  space  is  as  the  pressure,  and  is  always  to  that  of  an  equal  bulk  of  the 
atmosphere,  as  the  height  of  the  column  of  mercury  which  the  said  air  can  support 
in  a  Torricellian  tube,  is  to  the  height  of  the  mercury  in  the  barometer:  and  like- 
wise, that  the  resistance  of  air  increases  with  the  diminution  of  the  including  space  ; 
or,  vice  versa,  that  the  space  which  a  given  weight  of  air  is  capable  of  occupying, 
lessens  as  the  pressure  increases. 

155.  It  remains  to  be  shown  that  the  resistance  of  air  to  compression  increases  as 
the  quantity  in  any  space  increases. 

156.  If,  by  means  of  the  condenser,  C,  (the  valve  cock,  v  c,  and  the  cock,  c,  being 
open,)  air  be  injected  into  the  vessels,  A  and  B  at  the  same  time,  it  will  be  found 
that  the  liquid  in  the  vase,  V,  will  mount  into  the  flask,  F,  and  that  when  the  pres- 
sure is  adequate  to  cause  the  air  in  this  to  be  reduced  to  half  its  previous  volume, 
the  mercury  in  the  tube,  TT,  will  have  the  same  height  as  in  the  previous  experi- 
ment ;  because  the  density  of  the  air,  and  of  course  its  quantity  and  reactive  power, 
are  doubled  in  one  case  no  less  than  in  the  other. 

157.  The  communication  between  the  condenser  and  the  receiver,  A,  is  suspended 
during  the  first  mentioned  experiment,  by  closing  the  valve  ccck,  v  c.     This  cock 
is  opened  during  the  action  of  the  condenser  in  the  second  experiment;  and  like- 
wise another  cock  at  c,  which  serves  to  intercept  the  communication  between  the 
condenser  and  the  receiver,  B. 

Mechanical  Action  of  the  Lungs  in  Respiration  illustrated. 

158.  The  elevation  of  the  sternum  rarefies  the  air  within  the  cavity  of  the  thorax. 
Consequently,  the  atmospheric  pressure  not  being  adequately  resisted,  the  external 
air  rushes  through  the  trachea  into  the  lungs,  dilating  all  the  cells.     The  depression 
of  the  sternum  and  consequent  diminution  of  the  cavity  cause  the  air  which  had 
thus  entered,  or  an  equivalent  portion,  to  flow  out.     For  the  illustration  of  the  pro- 
cess here  described,  I  have  contrived  the  apparatus  represented  below. 

159.  A  tall  receiver,  R,  with  an  orifice,  O,  is  placed  in  a  globe  containing  water, 


0 


R 


30  IMPONDERABLE  SUBSTANCES. 

so  that  about  two-thirds  of  the  receiver  are  occupied  by  this  liquid,  the  remainder 
with  air,  whilst  a  bladder  is  so  suspended  from  the  orifice  as  not  to  touch  the  water. 

160.  The  atmosphere  has  access  to  the  cavity  of  the  bladder  through  its  neck,  and 
through  the  orifice  O  of  the  receiver,  but  not  to  the  space  A,  between  the  outside  of 
the  bladder  and  the  inside  of  the  receiver. 

161.  It  may  be  assumed  as  an  obvious  consequence  of  the  preceding  experiments, 
(154,  156)  that  the  pressure,  exerted  by  any  given  quantity  of  air,  is  inversely  as  the 
confining  space ;  or  in  other  words,  that  the  pressure  increases  as  the  space  lessens, 
and  diminishes  as  the  space  enlarges. 

162.  When  a  cavity  to  which  the  atmosphere  has  no  access  is  enlarged,  the 
density  of  the  contained  air  is  proportionably  diminished.     When  any  cavity  is  di- 
minished, the  density  of  the  contained  air  is  proportionably  increased.     But  if  the 
atmosphere,  meanwhile,  have  access  to  the  cavity,  it  will  by  its  influx  or  efflux  tend 
to  preserve  the  equilibrium  of  density  and  pressure  between  the  air  of  the  cavity  and 
the  external  medium.     These  consequences  are  well  known  to  ensue,  from  an  al- 
ternate enlargement  and  diminution  of  capacity,  during  the  working  of  an  air  pump, 
a  condenser,  or  bellows. 

163.  In  like  manner  the  elevation  of  the  receiver,  R,  enlarging  the  cavity  within 
it  unoccupied  by  water,  causes  the  air  to  rush  in  through  the  orifice,  O  ;  and  the  re- 
versal  of  the  motion,  reducing  the  cavity,  causes  the  air  to  rush  out  through  the 
same  aperture.    The  bladder  is  so  situated  as  to  receive  all  the  air  that  enters,  and  to 
supply  all  that  is  expelled.     Hence  when  the  receiver  is  lifted,  the  bladder  is  in- 
flated, and  when  lowered  to  its  previous  position,  the  bladder  resumes  its  original 
dimensions. 

164.  Supposing  the  space,  A,  between  the  outside  of  the  bladder  and  the  inside  of 
the  receiver,  to  represent  the  space  between  the  outside  of  the  lungs  and  the  inside 
of  the  thorax,  the  cavity  of  the  bladder  representing  the  cavities  of  the  lungs,  and 
the  orifice,  O,  performing  the  part  of  the  trachea  and  nostrils,  the  explanation,  above 
given,  will  be  as  applicable  to  the  apparatus  by  which  nature  enables  us  to  breathe, 
as  to  that  employed  in  the  preceding  illustration. 


EXPANSION  OF  ELASTIC  FLUIDS. 

165.  Having  by  means  of  the  preceding  digression  ex- 
plained the  nature  and  extent  of  atmospheric  pressure,  I 
shall  proceed  to  show  the  important  influence  exercised 
by  it  in  all  chemical  processes  in  which  elastic  fluids  are 
concerned. 

166.  It  has  been  demonstrated  (54)  in  illustrating  the 
principle  of  Sanctorio's  thermometer,  that  the  bulk  of  the 
air  in  any  space  varies  with  the  temperature. 

167.  It  has  been  shown  that  the  same  effect  may  be 
produced  by  variations  in  atmospheric  pressure.     (115, 
119,  120,  122.) 

168.  It  follows  that  the  volume  of  elastic  fluids  is  in- 
versely as  the  pressure  and  directly  as  the  heat.     In  other 
words,  the  less  the  pressure  arid  the  greater  the  heat,  the. 
larger  their  bulk ;  and  vice  versa,  the  less  the  heat,  and 
the  greater  the  pressure,  the  less  their  bulk. 

169.  Agreeably  to  the  observations  of  Dalton,  Gay-Lussac,  and  Crich- 
ton,  1000  parts  of  atmospheric  air,  in  rising  from  the  temperature  of  32° 
to  212°,  will  expand  so  as  to  measure  1375  parts  nearly,  or,  ^-g^th  of  the 
bulk  which  it  would  have  at  32®,  for  each  degree  of  heat  which  it  may  re- 
ceive. 


CALORIC.  31 

170.  Having,  therefore,  any  given  bulk  of  dry  air,  100  cubic  inches  for 
instance  at  60°,  to  find  its  bulk  at  any  other  temperature,  suppose  at  80°, 
we  must  in  the  first  place  consider  that  480  parts  at  32°  would  at  60°, 
adding  one  part  for  every  degree  above  32°,  be  508  parts ;  and  would  by 
a  proportionate  increase,  become  at  80°,  528  parts.     But  if  508  parts  at 
60°  become  528  at  80°,  what  will  100  parts  at  60°  become  when  heated 
to  80°. 

508    :  528  :  :  100    :  103.9 

171.  It  has  been  inferred  by  the  same  distinguished  philosophers,  that 
all  aeriform  substances,  whether  gases  or  vapours,  are  expanded  by  heat  at 
the  same  rate- as  dry  atmospheric  air,  if  they  be  not  in  contact  with  any 
vaporizable  matter,  in  the  liquid  or  solid  state,  which  by  vaporizing  or  con- 
densing may  vary  the  result. 

Theory  of  Expansion. 

172.  The  expansion  of  matter,  whether  solid,  liquid,  or  aeriform,  by  an 
increase  of  temperature,  may  be  thus  explained. 

173.  In  proportion  as  the  temperature  within  any  space  is  raised,  there 
will  be  more  caloric  in  the  vicinity  of  the  particles  of  any  mass  contained 
in  the  space.     The  more  caloric  in  the  vicinity  of  the  particles,  the  more 
of  it  will  combine  with  them ;  and  in  proportion  to  the  quantity  of  caloric 
thus  combined,  will  they  be  actuated  by  that  reciprocally  repellent  power, 
which,  in  proportion  to  its  intensity,  regulates  their  distance  from  each 
other. 

174.  There  may  be  some  analogy  between  the  mode  in  which  each 
ponderable  atom  is  surrounded  by  the  caloric  which  it  attracts,  and  that  in 
which  the  earth  is  surrounded  by  the  atmosphere;  and  as  in  the  latter  case, 
so  probably  in  the  former,  the  density  is  inversely  as  the  square  of  the  dis- 
tance. 

175.  At  a  height  at  which  the  atmospheric  pressure  does  not  exceed  a 
grain  to  the  square  inch,  suppose  it  to  be  doubled,  and  supported  at  that  in- 
creased pressure  by  a  supply  of  air  from  some  remote  region ;  is  it  not 
evident  that  a  condensation  would  ensue  in  all  the  inferior  strata  of  the 
atmosphere,  until  the  pressure  would  be  doubled  throughout,  so  as  to  be- 
come at  the  terrestrial  surface,  30  pounds,  instead  of  the  present  pressure 
of  15  pounds?    Yet  the  pressure  at  the  point  from  which  the  change  would 
be  propagated  would  not  exceed  two  grains  per  square  inch. 

176.  In  like  manner,  it  may  be  presumed  that  the  atmospheres  of  caloric 
are  increased  in  quantity  and  density  about  their  respective  atoms,  by  a 
slight  increase  in  the  calorific  tension  of  the  external  medium. 

Demonstration  that  Atmospheric  Pressure  opposes  and  limits 
Chemical  Action,  where  Elastic  Fluids  are  to  be  generated 
or  evolved. 

Of  Vaporization. 

177.  Water  would  boil  at  a  lower  temperature  than 
212°,  if  the  atmospheric  pressure  was  lessened;  for  when  it 


32 


IMPONDERABLE  SUBSTANCES. 


has  ceased  to  boil  In  the  open  air,  it  will  begin  to  boil  again 
in  an  exhausted  receiver.  Those  who 
ascend  mountains  find  that  for  every 
530  feet  of  elevation,  the  boiling  point 
is  lowered  one  degree  of  Fahrenheit's 
thermometer.  It  is,  in  fact,  lowered  or 
raised  rinnrth  of  a  degree  for  every  tenth 
of  an  inch  of  variation  in  the  height  of 
the  mercury  in  the  barometer. 

Ebullition  from  diminished  Pressure. 

178.  The  adjoining  figure  represents  a  vessel  of 
water  boiling  within  a  receiver,  in  consequence  of 
the  diminution  of  pressure  by  exhaustion. 


Culinary  Paradox. — Ebullition  by  Cold. 

179.  A  matrass,  half  full  of  water,  be- 
ing heated   until  all  the  contained   air  is 
superseded  by  steam,  the  orifice  is  closed 
so  as  to  be  perfectly  air-tight.    The  matrass 
is  then  supported  upon  its  neck,  in  an  in- 
verted position,  by  means  of  a   circular 
block  of  wood.     A   partial  condensation 
of  the  steam  soon  follows  from  the  re- 
frigeration  of  that   portion   of  the   glass 
which  is  not  in  contact  with  the  water. 
The  pressure  of  the  steam  upon  the  liquid 
of  course   becomes   less,  and   its   boiling 
point   is   necessarily   lowered.     Hence   it 
begins  again  to  present  all  the  phenomena 
of  ebullition,   and   will    continue    boiling 
sometimes  for  nearly  an  hour. 

180.  By  the  application  of  ice,  or  of  a 
sponge  soaked  in  cold  water,  the  ebullition 
is  accelerated ;  because  the  aqueous  vapour 
which  opposes  it,  is  in  that  case  more  ra- 
pidly condensed ;  but  as  the  caloric  is  at  the  same  time  more  rapidly  ab- 
stracted from  the  water  by  the  increased  evolution  of  vapour  to  replace 
that  which  is  condensed,  the  boiling  will  cease  the  sooner. 


CALORIC. 


33 


Improved  Apparatus  for  showing  the  Culinary  Paradox. 

181.  This  figure  illustrates  a  new  and  in- 
structive method  of  effecting  ebullition  by  cold. 

182.  The  apparatus  consists  principally  of 
a  glass  matrass,  with  a  neck  of  about  three 
feet  in  length,  tapering  to  an  orifice  of  about 
a  quarter  of  an  inch  in  diameter.     The  bulb 
is  bulged  inwards  in  the  part  directly  oppo- 
site the  neck,  so  as  to  create  a  cavity  capa- 
ble of  holding  any  matter  which  it  may  be 
desirable  to  have  situated  therein.     In  addi- 
tion to  the  matrass,  a  receptacle  holding  a 
few  pounds  of  mercury  is  requisite.     The 
bulb  of  the  matrass  being  rather  less  than 
half  full  of  water,  and  this  being  heated  to 
ebullition,  the   orifice  should  be  closed  by 
the  finger,  defended  by  a  piece  of  gum-elas- 
tic, and  depressed  below  the  surface  of  the 
mercury;  the  whole  being  supported  as  re- 
presented in  the  figure.     Under  these  cir- 
cumstances, the  mercury  rises  as  the  tempe- 
rature of  the  water  declines,  indicating  the 
consequent  diminution  of  pressure  within  the 
bulb.     Meanwhile,  the   decline  of  pressure 
lowering  the  boiling  point  of  the  water,  the 
ebullition  continues  till  the  mercury  rises  in 

the  neck  nearly  to  the  height  of  the  mercury  in  the  barometer. 

183.  By  introducing  into  the  cup  formed  by  the  bulging  of  the  bulb,  cold 
water,  alcohol,  ether,  or  ice,  the  refrigeration,  the  diminution  of  pressure, 
and  the  ebullition,  are  all  simultaneously  accelerated;  since  these  results 
are  reciprocally  dependent  on  each  other. 

Experimental  Proof  that  some  Liquids  would  be  permanently  aeriform, 
if  Atmospheric  Pressure  were  removed. 

184.  The  power  of  certain  liquids,  common  ether 
for  instance,  to  assume  in  vacuo,  at  ordinary  tempe- 
ratures, the  aeriform  state,  in  opposition  even  to  the 
pressure  of  a  column  of  mercury,  may  be  shown  by 
the  following  experiment. 

185.  A  glass  funnel  is  ground  to  fit  air-tight  into 
the  neck  of  a  glass  decanter,  so  that  the  stem  of  the 
funnel  may  reach  nearly  to  the  bottom  of  the  decan- 
ter, as  represented  in  the  adjoining  cut.     The  decan- 
ter is  filled  with  mercury,  with  the  exception  of  a  small 
portion  of  the  neck,  which  is  occupied  by  ether.     The 
stem  of  the  funnel  is  then  introduced  into  the  neck  of 
the  decanter,  so  as  to  be  air-tight ;  and  the  whole  be- 
ing included  in  a  receiver,  the  air  is  withdrawn  by  a 
pump.     The  ether  converted  into  vapour  will  force 
the  mercury  to  rise  from  the  decanter,  through  the 
stem,  into  the  wider  part  of  the  funnel. 

186.  Rationale. — The  attraction  between  the  ponderable  particles  of  the 
ether,  and  those  of  caloric,  can  be  indulged  only  in  opposition  to  the  reci- 
procally repulsive  power  of  the  latter ;  since  one  tends  to  rarefy  the  caloric, 
5 


34 


IMPONDERABLE  SUBSTANCES. 


the  other  to  condense  it  into  the  limited  space  occupied  by  the  ether.  It 
follows  that  the  caloric  cannot  combine  with  the  ponderable  matter  beyond 
the  point  at  which  the  repulsive  power  becomes  equal  to  the  attractive.  But 
the  repulsion  exercised  by  the  same  number  of  particles  of  caloric  will  be 
greater  as  the  space  is  less,  and  vice  versa.  The  larger,  therefore,  the 
space  occupied  by  the  ponderable  particles  of  the  ether,  the  more  caloric 
may  combine  with  them,  without  rendering  its  reciprocally  repulsive  power 
paramount  to  its  attraction  for  them. 

187.  The  removal  of  atmospheric  pressure,  by  allowing  the  ponderable 
particles  to  occupy  a  larger  space,  enables  them  to  combine  with  that  addi- 
tional quantity  of  caloric  which  is  necessary  to  the  aeriform  state. 

188.  This  explanation  may,  of  course,  be  extended  to  the  ebullition  of 
other  liquids  in  vacuo,  at  temperatures  lower  than  those  at  which  they 
boil  in  the  air.     It  is  obviously  applicable  to  the  two  preceding  illustra- 
tions. 

Boiling  Point  elevated  by  Pressure. 

189.  Into  a  small  glass  matrass,  with  a  bulb 
of  about  an  inch  and  a  half  in  diameter  and  a 
neck  of  about  a  quarter  of  an  inch  in  bore,  in- 
troduce nearly  half  as  much  ether  as  would  fill 
it.     Closing  the  orifice  with  the  thumb,  hold  the 
bulb  over  the  flame  of  a  spirit  lamp,  until  the 
effort  of  the  generated  vapour  to  escape  becomes 
difficult  to  resist.     Removing  the  matrass  to  a 
sufficient  distance  from  the  lamp,  lift  the  thumb 
from  the  orifice.     The  ether,  previously  qui- 
escent, will  rise  up  in  a  foam,  produced  by  the 
rapid  extrication  of  its  vapour. 

190.  This  experiment  may  be  performed  with 
less  risk,  by  plunging  the  matrass  in  hot  water, 
instead  of  heating  it  by  a  lamp. 


191.  Having  supplied  a  small  flask  with  a  quantity 
of  mercury,  sufficient  to  cover  the  bottom  to  about  an 
inch  in  depth,  let  there  be  a  glass  tube  so  introduced 
through  the  neck,  and  luted  air-tight,  as  to  extend 
nearly  an  inch  below  the  mercurial  surface.  If  the 
flask  thus  prepared,  be  duly  heated,  the  ether  will  be 
proportion  ably  vapourized,  and  the  generated  vapour 
pressing  on  the  mercury,  will  cause  a  column  of  this 
metallic  liquid  to  rise  within  the  tube,  and  thus  to  in- 
dicate and  measure  the  pressure.  It  is  necessary  to 
discontinue  the  heat,  when  the  mercurial  column  ap- 
proaches the  upper  orifice  of  the  tube,  in  order  to  pre- 
vent the  metal  from  overflowing. 


High  Pressure  Boiler. 


(Page  35.) 


CALORIC.  35 


High  Pressure  Boiler. 

192.  That  the  temperature  of  steam  increases  with  the  pressure,  may  be 
demonstrated  by  means  of  a  small  boiler,  such  as  is  represented  in  the 
opposite  engraving. 

193.  A  glass  tube,  of  about  five  feet  in  height,  and  of  half  an  inch 
in  bore  nearly,  is  secured  into  an  aperture  in  a  very  strong  iron  boiler,  so 
as  to  be  air-tight,  and  so  as  to  be  concentric  with  the  axis  of  the  boiler. 
Within  the  boiler  the  tube  descends  in  such  manner  as  to  pass  through  the 
water  with  which  it  is  supplied,  and  to  terminate  close  to  the  bottom,  be- 
neath a  small  quantity  of  mercury  purposely  introduced.     On  the  opposite 
side  of  the  boiler,  a  tube,  not  visible  in  the  engraving,  descends  into  it. 
This  tube  consists  of  about  two  inches  of  a  musket  barrel,  and  is  closed  at 
bottom.     The  object  of  it  is  to  contain  some  mercury,  into  which  the  bulb 
of  a  thermometer  may  be  plunged  for  ascertaining  the  temperature. 

194.  When  the  fire  has  been  applied  during  a  sufficient  time,  the  mercury 
will  rise  in  the  glass  tube  so  as  to  be  visible  above  the  boiler ;  and  con- 
tinuing to  rise  during  the  application  of  the  fire,  it  will  be  found  that,  with 
every  sensible  increment  in  its  height,  there  will  be  a  corresponding  rise  of 
the  mercury  in  the  thermometer. 

1 95.  In  front  of  the  tube,  as  represented  in  the  figure,  there  may  be  ob- 
served a  safety  valve  with  a  lever  and  weight  for  regulating  the  pressure. 
It  has  been  found  that,  when  the  effort  made  by  the  steam  to  escape,  in 
opposition  to  the  valve  thus  loaded,  is  equal  to  about  fifteen  pounds  for  every 
square  inch  in  the  area  of  the  aperture,  the  height  of  the  column  of  mer- 
cury, C  C,  raised  by  the  same  pressure,  is  about  equal  to  that  of  the  co- 
lumn of  this  metal,  usually  supported  by  atmospheric  pressure  in  the  tube 
of  a  barometer. 

196.  Hence  the  boiler,  under  these  circumstances,  is  conceived  to  sustain 
an  unbalanced  pressure  equivalent  to  one  atmosphere ;  and  for  every  addi- 
tional fifteen  pounds  per  square  inch,  required  upon  the  safety  valve  to  re- 
strain the  steam,  the  pressure  of  an  atmosphere  is  alleged  to  be  added.    To 
give  to  steam  at  212  degrees,  or  the  boiling  point,  such  an  augmentation  of 
power,  a  rise  of  38  degrees  is  sufficient,  making  the  temperature  equal  to 
250  degrees.     To  produce  a  pressure  of  four  atmospheres  about  293  de- 
grees would  be  necessary.     Eight  atmospheres  would  require  nearly  343 
degrees. 

197.  When  by  means  of  the  cock  an  escape  of  steam  is  allowed,  a  cor- 
responding decline  of  the  temperature  and  pressure  ensues. 

198.  If  the  steam,  as  it  issues  from  the  pipe,  be  received  under  a  portion 
of  water  of  known  temperature  and  weight,  the  consequent  accession  of 
heat  is  surprisingly  great,  when  contrasted  with  the  accession  of  weight 
derived  from  the  same  source.     It  has  in  fact  been  ascertained  that  one 
measure  of  water,  converted  into  aqueous  vapour,  will,  by  its  condensa- 
tion, raise  about  ten  measures  of  water  in  the  liquid  form  one  hundred 
degrees. 

Of  the  Incompetency  of  a  Jet  of  High  Steam  to  scald  at  a  certain 
Distance  from  the  Aperture. 

199.  Much  attention  has  been  excited  by  the  observation,  that  the  hands 
may  be  enveloped  in  a  jet  of  vapour  from  a  high  pressure  boiler  without 


36  IMPONDERABLE  SUBSTANCES. 

inconvenience,  at  a  certain  distance  from  the  aperture  through  which  it 


Experimental  Demonstration. 

200.  The  fact  that  the  hand  may  be  immersed  without 
injury  in  a  jet  of  steam  while  issuing  from  a  boiler,  if 
not  too  near  the  aperture,  experimentally  demonstrated. 

201.  Rationale. — Since  the  temperature,  density,  and  pressure,  which 
form  the  distinguishing  attributes  of  high  steam,  cannot  be  sustained  with- 
out  confinement,  steam  ceases  to  be  high  steam  as  soon  as  it  is  liberated. 
Consequently,  a  jet  from  a  high  pressure  boiler  is  essentially  no  more  than 
a  copious  jet  of  aqueous  vapour  at  the  heat  of  boiling  water. 

202.  The  only  distinguishing  characteristic,  derived  from  its  previously 
superior  temperature  and  density,  is  a  greater  velocity  of  efflux.     Without 
any  superiority  of  temperature,  the  high  pressure  jet  is  propelled  in{o  the 
atmosphere  with  a  momentum,  which  cannot  be  given  to  low  steam.    Hence 
the  rapid  refrigeration  to  which  the  former  is  subjected,  at  a  sufficient  dis- 
tance from  the  place  of  its  efflux  to  admit  of  an  extensive  diffusion  in  the 
atmosphere. 

Illustration  of  the  Process  by  which  Thermometers  are  supplied  with  the  Liquids  used 

in  their  construction. 


203.  A  globe,  with  a  long  cylindrical  neck,  situated  as  in  the  preceding  figure, 
and  containing  a  small  quantity  of  water,  being  subjected  to  the  flame  of  a  lamp, 
the  water,  by  boiling,  will  soon  fill  the  cavity  of  the  globe  and  neck  with  steam. 
When  this  is  accomplished,  bubbles  of  air  will  cease  to  escape  from  the  orifice  of  the 
neck  through  the  water  in  the  vase. 

204.  The  apparatus  being  thus  prepared,  on  removing  the  lamp,  the  water  will 
quickly  rush  from  the  vase  into  the  vacuity  arising  from  the  condensation  of  the 
steam  within  the  globe. 


CALORIC. 


37 


Explosive  Power  of  Steam. 

205.  If  a  glass  bulb,  hermetically  sealed  while 
containing  a  small  quantity  of  water  be  suspend- 
ed by  a  wire  over  a  lamp  flame,  an  explosion  soon 
follows,  with  a  violence  and  noise  which  are  sur- 
prising,  when  contrasted   with   the   quantity   of 
water  by  which  they  are  occasioned. 

206.  Rationale. — Supposing  that  the  bulb  were, 
in  the  first  instance,  merely   filled   with  steam, 
without  any  water  in  the  liquid  form,  the  explana- 
tion of  this  phenomenon  would  be  comprised  in 
the  theory  of  expansion,  already  suggested.  (173.) 
In  that  case,  the  effort  of  the  steam  to  enlarge  itself, 
would  be  nearly  in  direct  arithmetical  proportion  to 
the  temperature ;  but  water  being  present  in  the  li- 
quid form,  while  the  expansive  power  of  the  steam, 
previously  in  existence,  is  increased,  more  steam 

is  generated  with  a  like  increased  power  of  expansion.  It  follows  that  the 
increments  of  heat  being  in  arithmetical  proportion,  the  explosive  power  of 
the  confined  vapour  will  increase  geometrically,  being  actually  doubled  as 
often  as  the  temperature  is  augmented  38°.  (196.) 

Interesting  Experiments  with  respect  to  Vaporization  under  extreme  Pres- 
sure, by  M.  Cagniard  de  la  Tour,  and  Mr.  Perkins. 

207.  Agreeably  to  some  experiments  performed  by  M.  Cagniard  de  la 
Tour,  in  which  liquids  were  exposed  to  heat  in  very  stout  tubes,  vaporiza- 
tion  was  performed  in  a  space  which  was  to  that  previously  occupied, — 

Ether,  as  2  to  1,  producing  a  pressure  of  33  atmos- 
pheres. 
Alcohol,  as  3  to  1,  producing  a  pressure  of  119  atmos- 

pheres. 

Water,  as  4  to  1,  producing  a  pressure  greater  than 
that  caused  by  the  alcohol. 


In  the  case  of 


208.  Mr.  Perkins  alleges  that  a  small  iron  boiler  of  great  strength  may  be  heated 
red-hot  while  holding  a  portion  of  water,  and  that  if,  under  these  circumstances,  an 
aperture  be  opened  of  \  of  an  inch  in  diameter,  the  steam  will  not  escape,  although 
upon  a  reduction  of  temperature,  it  will  rush  out  with  great  violence. 

209.  It  was  inferred  that  the  repulsion  between  the  particles  of  the  caloric  in 
union  with  the  water,  and  those  in  union  with  the  metallic  ring  bounding  the  aper- 
ture, was  paramount  to  the  pressure  tending  to  produce  the  expulsion  of  the  steam. 

210.  I  am  unable  to  reconcile  this  experiment  with  one  which  I  performed  by 
heating  to  incandescence,  in  a  forge  fire,  a  tube  of  iron,  of  which  the  bore  was  less 
than  i  of  an  inch,  while,  by  means  of  a  cock,  a  communication  with  a  high  pressure 
boiler  was  made.     Under  these  circumstances,  the  steam  was  not  prevented  from 
escaping  through  the  pipe. 

211.  It  appears  to  be  sufficiently  proved  that  the  quantity  of  caloric  combined  with 
a  given  weight  of  steam  is  always  the  same,  whatever  may  be  its  temperature;  the 
sensible  heat  increasing  and  the  latent  heat  diminishing  as  the  density  and  pressure 
are  augmented. 

Cold  and  Cloudiness  arising  from  Rarefaction. 

212.  Incipient  rarefaction  in  the  air  of  a  receiver  is  usually  indicated  by  a  cloud, 
which  disappears  when  the  exhaustion  has  proceeded  beyond  a  certain  point.     A 
delicate  thermometer  placed  in  the  receiver,  shows  that  a  decline  of  temperature 


JO  IMPONDERABLE  SUBSTANCES. 

accompanies  this  phenomenon.  We  may,  therefore,  infer  that  the  cloud  is  the  con- 
sequence of  refrigeration.  If  the  suggestions  be  correct  which  were  made  (Theory 
of  Expansion,  175)  respecting  the  mode  in  which  caloric  exists  in  atmospheres 
around  the  particles  of  ponderable  matter,  it  will  not  be  difficult  to  understand 
why  aeriform  fluids  should  absorb  more  caloric,  in  proportion  as  their  consti- 
tuent particles  are  enabled,  by  a  diminution  of  pressure,  to  become  more  remote. 
Hence,  by  rarefaction,  the  capacity  of  air  is  increased,  and  cold  is  produced,  which 
condenses  the  aqueous  vapour  until  its  sensible  heat  is  restored  by  an  accession  of 
caloric  from  the  surrounding  medium.  (184.) 

Cold  produced  by  the  Palm  Glass. 

213.  In  forming  the  bulbs  severally  at  the 
ends  of  the  glass  tube  represented  in  this 
figure,  one  is  furnished  with  a  perforated  pro- 
jecting beak.  By  warming  the  bulbs,  and 
plunging  the  orifice  of  the  beak  into  alcohol,  a 
portion  of  this  liquid  enters,  as  the  air  within 
contracts  in  returning  to  its  previous  tempera- 
ture. The  liquid,  thus  introduced,  is  to  be 
boiled  in  the  bulb  which  has  no  beak,  until 
the  whole  cavity  of  the  tube  and  of  both  bulbs, 
not  occupied  by  liquid  alcohol,  is  filled  with 
its  steam.  While  in  this  situation,  the  end  of 
the  beak  is  to  be  shortened  and  sealed,  by  sub- 
jecting it  to  the  flame  excited  by  a  blowpipe. 

214.  As  soon  as  the   instrument  becomes  cold,  the  steam,  which  had  filled  the 
space  vacant  of  liquid  alcohol,  condenses,  and  with  the  exception  of  a  slight  portion 
of  vapour,  which  is  always  emitted  by  liquids  when  relieved  from  atmospheric  pres- 
sure, a  vacuum  exists  within  the  bulb. 

215.  The  instrument,  thus  formed,  has  been  called  a  palm  glass;  because  the  phe- 
nomenon which  it  exhibits  is  seen  by  grasping  one  of  the  bulbs,  so  as  to  bring  it 
completely  into  contact  with  the  palm  of  the  hand.     One  of  the  bulbs  being  thus 
situated,  and  while  surcharged  with  the  alcohol,  and  held  in  the  position  represented 
in  the  figure,  both  the  liquid  and  vapour  are  propelled  from  it  into  the  other  bulb. 
This  phenomenon  combines  the  characteristics  of  the  differential  thermometer,  (69,) 
with  those  of  the  culinary  paradox,  (179,)  being  the  joint  effect  of  the  expansion,  and 
evolution  of  vapour,  in  one  part  of  the  apparatus,  and  its  contraction  and  condensa- 
tion in  another.     The  phenomena  are  precisely  similar,  whether  we  warm  the  lower 
bulb,  or  cool  the  upper  one  by  means  of  ice.     The  motive  for  recurring  to  the  expe- 
riment here  is  to  state  that,  as  soon  as  the  last  remnant  of  the  liquid  is  forced  from 
the  bulb  in  the  hand,  a  striking  sensation  of  cold  is  experienced  by  the  operator. 

216.  This  cold  has  been  attributed  generally  to  an  increase  of  the  capacity  of  the 
residual  vapour  for  caloric  in  consequence  of  its  attenuation.     The  analogy  is  evi- 
dent between  this  phenomenon  and  that  above  described,  as  taking  place  in  the  re- 
ceiver of  an  air  pump;  in  either  case  refrigeration  results  from  a  diminution  of 
density. 

Cold  consequent  to  relaxation  of  Pressure. 

217.  Cold  is  produced  whether  a  diminution  of  density  arise  from  relieving  con- 
densed air  from  compression,  or  from  subjecting  air  of  the  ordinary  density  to  rare- 
faction.    A  cloud  similar  to  that  which  has  been  described  as  arising  in  a  receiver 
partially  exhausted,  may  usually  be  observed  in  the  neck  of  a  bottle  recently  uncork- 
ed, in  which  a  quantity  of  gas  has  been  evolved  in  a  state  of  condensation  by  a  fer- 
menting liquor. 


CALORIC. 


39 


218.  The  apparatus  represented  in  the 
annexed  figure,  shows  the  influence  of 
relaxed  pressure  on  the  capacity  of  air 
for  heat  and  moisture. 

219.  A  glass  vessel  with  a  tubulure  and 
a  neck  has  an  air  thermometer  fastened 
air-tight  by  means  of  a  cork  into  the  form- 
er, while  a  gum-elastic  bag  is  tied  upon 
the  latter.     Before  closing  the  bulb,  the 
inside  should  be  moistened.     Under  these 
circumstances,  if  the  bag,  after  due  com- 
pression by  the  hand,  be  suddenly  re- 
leased, a  cloud   will  appear  within  the 
bulb,  adequate,  in  the  solar  rays,  to  pro- 
duce  prismatic  colours.      At  the   same 
time  the  thermometer  will  show  that  the 
compression  is  productive  of  warmth,  the 
relaxation  of  cold. 

220.  The  cloud  which  has  been  shown 
to  arise  (212,)  in  air  suddenly  rarefied,  has 
been  much  insisted  upon  of  late,  by  Mr. 
Espy,  as  illustrating  a  meteorological  pro- 
cess, which  he  considers  as  the  principal 
cause  of  rain  storms.     This  induced  me 
to  make  some  experiments  in  order  to 
elucidate  this  subject. 


221.  Large  globes,  each  containing  about  a  cubic  foot  of  space,  furnished  with 
thermometers  and  hygrometers,  were  made  to  communicate,  respectively,  with  re- 
servoirs of  perfectly  dry  air,  and  of  air  replete  with  aqueous  vapour.*     The  cold, 
ultimately  acquired  by  any  degree  of  rarefaction,  appeared  to  be  the  same,  whether 
the  air  was  in  the  one  state  or  the  other;  provided  that  the  air,  replete  with  aqueous 
vapour,  was  not  in  contact  with  liquid  water  in  the  vessel  subjected  to  exhaustion. 
When  water  was  present,  in  consequence  of  the  formation  of  additional  vapour,  and 
a  consequent  absorption  of  caloric,  the  cold  produced  was  nearly  twice  as  great  as 
when  the  air  was  not  in  contact  with  liquid  water ;  being  nearly  as  9  to  5. 

222.  Under  the  circumstances  last  mentioned,  the  hygrometer  was  motionless; 
whereas,  when  no  liquid  water  was  accessible,  the  space,  although  previously  satu- 
rated with  vapour,  by  the  removal  of  a  portion  of  it  together  with  the  air  which  is 
withdrawn  by  the  exhaustion,  acquires  a  capacity  for  more  vapour;  and  hence  the 
hygrometer,  by  an  abstraction  of  one-third  of  the  air,  revolved  more  than  sixty  de- 
grees towards  dryness.     But  when  a  smaller  receiver  (after  being  subjected  to  a 
diminution  of  pressure  of  about  ten  inches  of  mercury,  so  as  to  cause  the  index  of 
the  hygrometer  to  move  about  thirty-five  degrees  towards  dryness)  was  surrounded 
by  a  freezing  mixture,  until  a  thermometer  in  the  axis  of  the  receiver  stood  at  three 
degrees  below  freezing,  the  hygrometer  revolved  towards  dampness,  until  it  went 
about  ten  degrees  beyond  the  point  at  which  it  rested  when  the  process  commenced. 

223.  It  appears,  therefore,  that  the  dryness  produced  by  the  degree  of  rarefaction 
employed  is  more  than  counterbalanced  by  a  freezing  temperature. 

224.  As  respects  the  heat  imparted  to  the  air  above  mentioned,  the  fact,  that  the 
ultimate  refrigeration  in  the  case  of  air  replete  with  vapour,  and  in  that  of  anhy- 
drous air,  was  equally  great,  and  that  when  water  was  present  the  cold  was  greater 
in  the  damp  vessel,  led  to  the  idea,  that  the  heat  arising  under  such  circumstances 
could  not  have  much  efficacy  in  augmenting  the  buoyancy  of  an  ascending  column 
of  air :  but  when,  by  an  appropriate  mechanism,  the  refrigeration  was  measured  by 
the  difference  of  pressure  at  the  moment  when  the  exhaustion  was  arrested,  and 
when  the  thermometer  had  become  stationary,  it  was  found  creteris  paribus,  that  the 
reduction  of  pressure  arising  from  cold  was  at  least  one-half  greater  in  the  anhy- 
drous air,  than  in  the  air  replete  with  vapour.    This  difference  seems  to  be  owing  to 
a  loan  of  latent  heat,made  by  the  contained  moisture,  or  transferred  from  the  appa- 


*  The  hygrometers  were  constructed  by  means  of  the  beard  of  the  avena  sengitiva, 
or  wild  oat,  also  called  animated  oat. 


40  IMPONDERABLE  SUBSTANCES. 

ratus  by  its  intervention,  which  checks  the  refrigeration ;  yet,  ultimately,  the  whole 
of  the  moisture  being  converted  into  vapour,  the  aggregate  refrigeration  does  not 
differ  in  the  two  cases. 

225.  Agreeably  to  Dalton's  tables,  at  70°  the  quantity  of  moisture  in  31  grains  or 
100  cubic  inches  of  air,  is  551-lOOOths  of  a  grain.     The  space  allotted  to  this  weight 
of  vapour  being  doubled,  it  would  remain  uncondensed  at  45°  F.,  being  associated 
with  the  same  weight,  but  double  the  volume,  of  air;  but  at  32°,  notwithstanding 
the  doubling  of  the  space,  only  356-lOOOths  of  a  grain  would  remain  in  the  aeriform 
state  ;  of  course  551  —  356  =  195-lOOOths,  or  nearly  2-10ths  of  a  grain,  would  be 
precipitated. 

226.  The  latent  heat  given  out  by  the  condensation  of  this  vapour,  would  heat,  as 


25°  F.  As  air,  at  32°  F.,  expands  l-480ths  for  each  additional  degree,  the  difference 
of  bulk,  arising  from  the  heat  received,  as  above  calculated,  would  be  25-480ths,  or 
l-19ths  nearly. 

227.  When  air,  replete  with  aqueous  vapour,  was  admitted  into  a  receiver  par- 
tially exhausted,  and  containing  liquid  water,  a  copious  precipitation  of  moisture  en- 
sued, and  a  rise  of  temperature  greater  than  when  perfectly  dry  air  was  allowed  to 
enter  a  vessel  containing  rarefied  air  in  the  same  state.     In  the  instance  first  men- 
tioned, a  portion  of  vapour  arises  into  the  place  of  that  which  is  withdrawn  during 
the  partial  exhaustion.     Hence  when  the  air,  containing  its  full  proportion  of  va- 
pour, enters,  there  is  an  excess  of  vapour  which  must  precipitate,  causing  a  cloud, 
and  an  evolution  of  latent  heat  from  the  aqueous  particles  previously  in  the  aeriform 
state.    As  the  enlargement  of  the  space  occupied  by  a  sponge,  allows,  proportiona- 
bly,  a  larger  quantity  of  any  liquid  to  enter  its  cells,  so  any  rarefaction  of  the  air 
when  in  contact  with  water,  consequent  on  increase  of  heat  or  diminution  of  pres- 
sure, permits  a  proportionably  larger  volume  of  vapour  to  associate  itself  with  a 
given  weight  of  the  air.     When,  subsequently,  by  the  afflux  of  wind  replete  with 
aqueous  vapour,  the  density  of  the  aggregate  is  increased,  a  portion  of  the  vapour 
equivalent  to  the  condensation  must  be  condensed,  giving  out  latent  heat,  excepting 
so  far  as  the  heat  thus  evolved,  being  retained  by  the  air,  raises  the  dew  point. 

228.  Hence,  whenever  a  diminution  of  density  of  the  air  inland  causes  an  influx 
of  sea  air  to  restore  the  equilibrium,  there  may  result  a  condensation  of  aqueous  va- 
pour, and  evolution  of  heat,  tending  to  promote  an  ascending  current.    This  process 
being  followed  by  that  which  Mr.  Espy  has  pointed  out,  of  the  transfer  of  heat  from 
vapour  to  air,  during  its  ascent  to  the  region  of  the  clouds,  and  consequent  precipi- 
tation of  moisture,  is  probably  among  the  efficient  causes  of  those  wen-electrical  rain 
storms,  during  which  water  from  the  Gulf  of  Mexico,  or  from  the  Atlantic,  is  trans- 
ferred to  the  soil  of  the  United  States. 

Of  the  Influence  of  the  Atmosphere  in  promoting  Evapora- 
tion. 

229.  It  has  been  seen  that  by  its  pressure  the  atmo- 
sphere opposes  vaporization;  yet  a  free  access  of  air  is 
found  indispensable  in  the  desiccation  of  hay,  or  in  the 
evaporation  of  water  or  other  solvents.  It  was  at  one 
time  generally  conceived  that  evaporation  resulted  from 
an  affinity  between  the  liquid  and  the  air,  analogous  to 
that  between  water  and  sugar,  or  alcohol  and  resin;  but 
in  consequence  of  the  observations  of  several  distinguished 
philosophers,  a  different  view  of  this  subject  has  been  lat- 
terly entertained.  It  has  in  fact  been  ascertained  that  the 
quantity  of  aqueous  vapour,  in  any  space  having  sufficient 
access  to  liquid  water,  is  always  directly  as  the  tempera- 
ture, whether  there  be  a  plenum  or  a  vacuum,  or  whatever 
may  be  the  density  of  the  air  simultaneously  present. 


CALORIC.  41 

230.  It  has  been  alleged  that  a  current  of  atmospheric 
particles  promotes  evaporation,  only  by  removing  the  ne- 
cessity to  which  the  vapour  would  otherwise  be  exposed, 
of  diffusing  itself  through  the  atmospheric  interstices  to  a 
greater  distance. 

231.  Nevertheless,  it  appears  to  me  that  the  influence 
of  a  current  of  atmospheric  air,  in  promoting  evaporation, 
is  greater  than  can  be  reasonably  thus  accounted  for. 

232.  It  is  difficult  to  conceive  that  the  elements  of  at- 
mospheric air  should  have  no  affinity  for  those  of  liquids; 
or  that,  if  such  affinity  exist,  it  should  not  promote  the 
process  of  evaporation.     Nothing  can  be  more  certain 
than  that  evaporation  is  accelerated  in  proportion  to  the 
extent  to  which  contact  may  be  induced  between  the  aeri- 
form and  liquid  particles.    Hence  when  surfaces,  moistened 
with  such  volatile  liquids  as  sulphuret  of  carbon,  or  the 
more  volatile  ethers,  are  exposed  to  the  wind,  or  to  a  blast, 
intense  cold  is  produced  by  the  accelerated  evaporation. 
It  is  well  known  that  the  direction  of  the  wind  becomes 
evident  from  the  sensation  of  coldness,  experienced  in  that 
part  of  the  wetted  finger  on  which  it  blows.    With  the  re- 
frigerating influence  of  a  breeze,  when  the  skin  is  moistened 
by  perspiration,  we  are  all  familiar. 

233.  The  processes  of  evaporation,  and  vaporization  in 
the  sense  of  ebullition,  cannot  be  confounded  in  practice, 
however  they  may  be  identified  agreeably  to  prevailing 
theories.     In  either  case,  heat  is  requisite,  though  much 
less  is  necessary  in  that  of  evaporation;  but  other  things 
being  equal,  the  process  last  mentioned,  is  accelerated  in 
proportion  to  the  extent  of  surface  exposed  to  the  air,  while 
ebullition  takes  place  in  proportion  to  the  surface  exposed 
to  the  fire,  without  access  of  air.    It  only  requires  that  the 
vapour  generated  should  have  an   aperture  sufficient  to 
allow  of  its  escape,  without  increase  of  pressure.     Hence 
evaporating  vessels  are  made  broad  and  shallow,  while 
boilers  may  be  made  deep  with  narrow  openings. 

Cold  produced  by  the  Evaporation  of  Ether  when  accelerated 
by  a  Current  of  Air. 

234.  The  cold,  produced  by  evaporation  accelerated  by 
a  current  of  air,  may  be  advantageously  shown  by  subject- 
ing a  thermometer  bulb  simultaneously  to  a  jet  of  ether, 

6 


42  IMPONDERABLE  SUBSTANCES. 

and  a  blast  from  a  bellows,  so  that  the  aerial  and  ethereal 
particles  may  be  thoroughly  mingled  just  before  reaching 
the  bulb.  Water  may  be  frozen  in  a  bulb  thus  refrige- 
rated. 

235.  Agreeably  to  the  principle  above  illustrated,  (217)  that  when  air  is  liberated 
from  a  state  of  compression,  cold  ensues,  I  have  lately  contrived  a  new  mode  of  ex- 
hibiting the  vaporization  of  ether,  so  as  to  freeze  water  on  a  more  extensive  scale, 
and  on  a  much  more  striking  manner  than  heretofore.     Between  the  lower  part  of  a 
very  strong  vessel  of  sheet  iron,  capable  of  holding  40  gallons,  and  the  "hydrant" 
pipes  by  which  our  city  is  supplied  with  water,  a  communication  is  made  by  means 
of  a  pipe  and  cock,  so  as  to  be  opened  or  closed  at  pleasure.     The  vessel  is  previous- 
ly filled  with  air,  by  allowing  it  to  discharge  any  water  which  it  may  hold  through  a 
cock.     Under  these  circumstances,  on  opening  the  communication  with  the  hydrant 
pipes,  the  air  within  the  vessel  may  be   subjected  to  a  pressure  of  more  than  one 
atmosphere.  (154.)     If  by  means  of  a  suitable  leaden  pipe,  furnished  with  a  cock, 
and  terminating  with  a  capillary  orifice,  the  air  be  allowed  to  blow  into  some  ether 
and  water  contained  in  a  thin  capsule,  the  ether  will  be  rapidly  vaporized,  and  the 
water  soon  frozen. 

236.  In  this  experiment,  in  lieu  of  hydric  (sulphuric)  ether,  we  employ  the  new 
form  of  hyponitrous  ether  which  I  have  lately  discovered,  the  congelation  will  be 
more  rapidly  accomplished. 

237.  It  will  hereafter  be  shown,  that,  by  analogous  causes,  when  solid  carbonic 
acid  is  thrown  into  ether,  a  refrigeration  is  produced  by  which  mercury  may  be 
rapidly  frozen. 

Definition  of  Vapour  by  Berzelius. 

238.  Berzelius  objects  to  the  use  of  the  word  vapour  as  implying  a  condensible 
aeriform  fluid.     He  uses  it  in  the  sense  in  which  English  authors  employ  the  word 
fog,  or  cloud.     Vapour  and  steam  were  originally,  and  still  are  used  in  this  sense, 
yet  the  fluid  which  is  used  to  propel  steam  engines,  and  to  which  they  owe  their 
distinguishing  name,  can  only  consist  of  water  in  the  aeriform  state  in  which  it  is  by 
the  distinguished  Swede  designated  as  aqueous  gas.     Johnson  defines  steam  to  be 
the  smoke  or  vapour  of  any  thing  hot  and  moist.     Of  course  steam  smoke  and  va- 
pour have  in  some  cases  been  used  synonymously.     I  have  elsewhere  mentioned 
that  before  Black's  discoveries  and  inferences  were  published,  atmospheric  air  was 
the  only  aeriform   fluid  whose  existence  was  recognised.     Hence  the  use  of  the 
words  steam  and  vapour  has  grown  with  our  knowledge,  and  consequently  the  names 
applied  to  visible  steam  or  vapour  have  been  extended  to  mean  the  invisible  aeri- 
form fluids  from  which  it  is  produced  by  refrigeration.     I  have  some  repugnance  to 
designating  by  a  common  epithet,  permanent  gases,  and  the   condensible  elastic 
fluids  produced  from  liquids  above  their  boiling  points.     I  do  not  see  that  any  dis- 
advantage arises  from  the  customary  use  of  the  word  vapour  to  designate  the  latter. 

Of  the  Opponent  Influence  of  Pressure  on  the  Extrication  of 
Gaseous  Substances  from  a  state  of  Combination. 

239.  When  one  of  the  ingredients  of  a  solid  or  liquid  is 
prone  to  assume  the  aeriform  state,  its  extrication  will  be 
more  or  less  easily  effected,  in  proportion  as  the  pressure 
of  the  air  is  diminished  or  increased. 


CALORIC.  43 


Escape  of  Carbonic  Acid  from  Carbonate  of  Lime  subjected  to  an  Acid, 
promoted  by  Exhaustion  and  checked  by  Condensation. 

240.  If  a  tall  cylindrical  jar,  containing  a  car- 
bonate undergoing  the  action  of  an  acid,  be  placed 
under  a  receiver,  and  the  air  withdrawn  by  an  air 
pump,  the  effervescence  will  be  augmented.  But 
if,  on  the  other  hand,  the  same  mixture  be  placed 
under  a  receiver,  in  which  the  pressure  is  increased 
by  condensation,  the  effervescence  will  be  dimi- 
nished. In  the  one  case,  the  effort  of  the  carbonic 
acid  to  assume  the  gaseous  state  is  repressed ;  in 
the  other,  facilitated.  Hence  the  advantage  of 
condensation  in  the  process  for  manufacturing  car- 
bonic acid  water.  Beyond  an  absorption  of  its 
own  bulk  of  the  gas,  the  affinity  of  the  water  is 
inadequate  to  subdue  the  tendency  of  the  acid 
to  the  aeriform  state;  but  when,  by  mechanical 
pressure,  a  great  number  of  volumes  of  the  gas 
are  condensed  into  the  space  ordinarily  occupied 
by  one,  the  water  combines  with  as  large  a  volume 
of  the  condensed  gas,  as  if  there  had  been  no  con- 
densation. 

Improved  Apparatus  for  showing  the  Influence  of  Pressure  on  Effervescence. 

241.  A  cylindrical  receiver,  about  30  inches  in  height,  and  3  inches  in  diameter, 
is  supported  on  a  wooden  block,  W,  between  upright  iron  rods,  RR.  each  at  the 
lower  end,  riveted  to  a  plate  of  iron  beneath  the  block,  and,  at  the  upper  end,  a 
screw  cut  and  furnished  with  a  nut.    By  means  of  these  screws  and  nuts  thus  formed, 
and  an  intervening  cross  bar,  B,  a  brass  disk.  D,  is  pressed  upon  the  rim  of  the  re- 
ceiver.   The  disk  is  so  ground  to  fit  to  the  rim  of  the  glass,  as  that,  with  the  aid  of 
some  beeswax  duly  softened  by  lard,  an  air-tight  juncture  may  be  made.     In  the 
middle  of  the  disk  there  is  an  aperture,  from  which   proceeds  a  stout   tube,  with  a 
cock  on  each  side,  severally  furnished    with   gallows  screws,  by  means  of  which 
lead  pipes  may  be  made  to  communicate  with  an  air  pump  on  one  side,  and  a  con- 
denser on  the  other.     The  tube  is  also  surmounted  by  a  cock,  into  which  a  glass 
funnel  is  cemented.    Before  closing  the  receiver,  some  solid  carbonate  in  pieces  must 
be  introduced  so  as  to  occupy  about  one-third  of  the  cavity.    For  this  purpose  I  have 
employed  carbonate  of  ammonia,   calcareous  spar  in  fragments,  and  latterly  clam 
shells.    In  either  of  these  substances,  carbonic  acid  and  lime  are  the  principal  ingre- 
dients.    The  carbonate  being  introduced,  and  the  disk  fastened  into  its  place,  as  re- 
presented in  the  figure,  diluted  muriatic  acid  may  be  added,  by  means  of  the  funnel 
and  cock,  in  quantity  sufficient  to  cover  the  carbonate. 

242.  In  consequence  of  the  superior  affinity  of  chlorine  for  the  calcium,  and  of  hy- 
drogen for  the  oxygen,  (in  the  oxide  of  calcium  or  lime)  the  carbonic  acid  is  expelled 
in  the  gaseous  form,  causing  a  perceptible  effervescence  or  foaming  of  the  liquid. 
If,  under  these  circumstances,  by  means  of  the  air  pump,  the  atmospheric  pressure 
within  the  receiver  be  lessened,  the  effervescence  increases  strikingly.     On  the  other 
hand,  if,  by  closing  the  communication  with  the  air  pump,  and  opening  that  with 
the  condenser  while  this  is  in  operation,  the  pressure  be  increased,  it  will  be  seen 
that  the  effervescence  is  diminished  proportionably. 

243.  This  experiment  is  much  facilitated  by  the  employment  of  an  air  pump, 
which  I  have  contrived,  by  which  we  can  either  exhaust  or  condense  at  pleasure. 

244.  Agreeably  to  experiments  performed  by  Faraday,  when  the  reaction  between 
an  acid  and  a  carbonate  is  made  to  take  place  in  a  stout  tube  hermetically  sealed, 
the  acid  may  be  separated  in  the  liquid  form.     According  to  the  more  recent  obser- 
vations of  Thilorier,  this  result  has  been  attained  upon  a  large  scale,  and  one  por- 
tion of  the  resulting  liquid  has  been  found  to  be  partially  frozen,  by  the  caloric  ab- 
stracted by  the  vaporization  of  the  other  portion. 


44  IMPONDERABLE  SUBSTANCES. 

245.  Thilorier's  process,  as  improved  by  Mitchell  and  others,  will  be  hereafter  il- 
lustrated and  explained. 

246.  By  analogous  means  various  substances,  naturally  gaseous,  have  been  liquefied 
by  Faraday,  as  will  be  mentioned  in  treating  of  those  substances. 

247.  All  the  cases  of  liquefaction  alluded  to,  are  referable  to  the  law  that  the 
power  of  any  matter  to  pass  to  the  aeriform  state  is,  ceteris  paribus,  less  in  proportion 
as  the  pressure  is  greater. 

Of  the  Screw  Rod  and  Plate  Frame,  employed  in  the  preceding  and  many  other 
Experiments. 

248.  The  means  by  which  the  glass  receiver,  employed  in  the  preceding  experi- 
ment, is  upheld  and  rendered  air-tight  by  the  rods,  R  R,  the  wooden  block,  W,  the 
bar,  B,  and  circular  plate  or  disk,  D,  is  one  to  which  I  shall  resort  frequently  in  the 
course  of  my  experiments.     Hence,  to  avoid  unnecessary  recurrence  to  analogous 
description,  I  shall  in  future  designate  as  a  screw  rod  and  plate  frame,  that  portion 
of  the  apparatus  above  described,  which  consists  of  the  block,  bar,  plate,  and  screw 
rods* 

249.  The  glass  in  this  case  is  made  quite  true  by  grinding  on  a  large  lap  wheel, 
such  as  is  employed  by  lapidaries.     The  same  objectls  effected  in  the  case  of  brass 
plates  without  grinding,  by  turning  them  in  a  lathe  with  a  slide  rest,  and  by  a  tool 
with  a  fine  pyramidal  point. 

OF  CAPACITIES  FOR  HEAT,  OR  SPECIFIC  HEAT. 

250.  The  power  of  equal  weights  of  different  substances, 
at  the  same  temperature,  in  cooling  or  warming  a  liquid  at 
a  temperature  different  from  their  own,  will  be  found  very 
unequal.     Thus  the  effect  of  a  given  weight  of  water 
being  1000,  the  effect  of  the  like  weight  of  glass  will  be 
137,  of  copper  94,  tin  51,  lead  29,  iron  110,  gold  29,  pla- 
tinum 31,  zinc  92,  silver  55.     If  equal  weights  of  water 
and  mercury,  at  different  temperatures,  be  mixed,  the  effect 
on  the  water  will  be  no  greater  than  if,  instead  of  the  mer- 
cury, Trth  of  its  weight  of  water,  at  the  same  temperature 
as  the  mercury,  had  been  added;  and  it  takes  twice  as 
much  mercury  by  measure  as  of  water  heated  to  the  same 
point  to  have  the  same  influence. 

251.  The  term  specific  heat  is  usually  employed  to  de- 
signate the  quantity  of  caloric  in  a  body  in  proportion  to 
its  weight  or  bulk,  as  specific  gravity  is  used  to  convey  an 
idea  of  weight  compared  with  bulk. 

252.  In  the  process  above  described,  the  specific  heats 
of  substances  are  found  in  order  to  estimate  their  capaci- 
ties; the  one  being  necessarily  as  the  other,  and  the  same 
series  of  numbers  expressive  of  either. 

*  Modification  of  the  screw  rod  and  plate  frame  are  represented  in  the  engraving 
referred  to  page  28.  (153.) 


CALORIC.  45 

Apparatus  for  illustrating  Capacities  for  Heat. 


T 


253.  Let  the  vessels  A,  B,  and  C,  be  supplied  with  water  through  the 
tube,  T,  which  communicates  with  each  of  them  by  a  horizontal  channel 
in  the  wooden  block.     The  water  will  rise  to  the  same  level  in  all.     Of 
course  the  resistance  made  by  the  water  in  each  vessel  to  the  entrance  of 
more  of  this  liquid  will  be  the  same,  and  will  be  measured  by  the  height  of 
the  column  of  water  in  the  tube,  T.     Hence,  if  the  height  of  this  column 
were  made  the  index  of  the  quantity  received  by  each  vessel,  it  would  lead 
to  an  impression  that  they  had  all  received  the  same  quantity.    But  it  must 
be  obvious  that  the  quantities  severally  received  will  be  as  different  as  are 
their  horizontal  areas.     Of  course  we  must  not  assume  the  resistance,  ex- 
erted by  the  water  within  the  vessels  against  a  further  accession  of  water 
from  the  tube,  as  any  evidence  of  an  equality  in  the  portions  previously 
received  by  them. 

254.  In  like  manner  the  height  of  the  mercury  in  the  thermometer  shows 
the  resistance  which  substances,  whose  temperature  it  measures,  are  making 
to  any  further  accession  of  caloric ;  but  it  does  not  indicate  the  quantities, 
respectively  received  by  them,  in  attaining  the  temperature  in  question. 
This  varies,  in  them,  in  proportion  to  their  attraction  for  this  self- repellent 
fluid ;  as  the  quantities  of  water  received  by  the  vessels,  A,  B,  C,  are  varied 
in  the  ratio  of  their  respective  areas. 

255.  Rationale. — It  may  be  conjectured  that  this  diversity  in  the  power 
of  substances,  equally  hot  or  cold,  in  influencing  temperature,  is  due  to  a 
difference  in  their  capacity  to  attract  caloric,  in  consequence  of  which  it 
probably  forms  denser  atmospheres  about  the  atoms  of  some  substances, 
than  it  does  about  those  of  others. 

256.  An  analogy  has  already  been  suggested  to  exist  between  the  man- 
ner in  which  these  calorific  atmospheres  surround  atoms,  and  that  in  which 
the  earth  is  surrounded  by  the  air ;  and  also  the  mode  has  been  suggested  in 
which  changes  of  temperature  in  the  external  medium  would  operate  upon 
the  density  of  such  atmospheres.     Supposing  these  preliminary  sugges- 
tions correct,  it  would  follow  that  the  quantity  of  caloric  absorbed  or  given 
out  at  each  exterior  change  of  temperature,  by  any  one  congeries  of  atoms, 
would  be  to  that  absorbed  or  given  out  by  any  other  congeries,  as  the  pre- 
vious condensation  of  caloric  in  the  one,  is  to  its  previous  condensation  in 
the  other.  (173, 174,  175,  176.)* 


*  A  notice  of  the  doctrine  of  Petit  and  Dulong  that  the  capacities  of  all  elemen- 
tary atoms  for  heat  are  the  same,  will  be  deferred  till  1  have  treated  of  atomic  pro- 
portions. 


46  IMPONDERABLE  SUBSTANCES. 

Of  the  Specific  Heat  of  Gaseous  Bodies. 

257.  It  was  suggested  by  Lambert  and  Pictet,  and  the  suggestion  was  after- 
wards sanctioned  by  Dalton,  that  space  may  have  a  capacity  for  caloric. 
Consistently  with  this  idea  the  quantity  of  caloric  in  a  given  space  should 
always  be  the  same  whatever  may  be  the  gaseous  fluid  occupied  by  it. 
This  is  consistent  with  the  fact  that  all  the  gases  have  the  same  capacity  for 
heat,  and  all  undergo  a  like  expansion,  in  consequence  of  a  like  increase  of 
temperature.     Agreeably  to  this  view  of  the  case,  the  cold  produced  by 
rarefaction,  as  in  the  experiment  with  the  exhausted  receiver  (212)  or  the 
palm  glass,  (215,)  the  heat  consequent  to  the  compression  of  air  (219) 
arises  from  the  caloric  in  the  air  or  vapour,  being  too  little  for  the  space 
allotted  to  the  air  in  one  case,  and  too  great  for  that  allotted  in  the  other. 
This  idea  seems  to  have  been  abandoned,  in  consequence  of  an  experiment 
performed  by  Gay  Lussac.     This  eminent  chemist  having  made  a  Torri- 
cellian vacuum  within  a  tall  cylindrical  glass  receiver,  about  3  inches  in 
diameter  and  39  in  height,  found  that  when  the  mercury  employed  was 
made  to  rise  or  sink  in  the  vacant  space  so  as  alternately  to  enlarge  or  di- 
minish it,  no  consequent  variation  of  the  temperature  took  place,  since  a 
delicate  air  thermometer,  of  which  the  bulb  was  included,  indicated  no 
change.     It  appeared,  nevertheless,  that  when  a  minute  quantity  of  air  was 
admitted,  any  increase  or  diminution  of  the  void  space,  consequent  to  the 
rise  or  fall  of  the  mercury,  was  as  productive,  as  the  same  thermometer 
showed,  of  a   corresponding   increase,   or   diminution,  of  sensible   heat. 
Hence  it  has  been  inferred  that  a  perfectly  void  space  has  no  capacity  for 
heat,  the  changes  of  temperature,  consequent  to  the  rarefaction  or  conden- 
sation of  aeriform  fluids,  being  altogether  caused  by  corresponding  changes 
in  the  capacity  of  those  fluids  for  caloric.     But  as  a  perfect  vacuum  must 
liberate  heat  with  perfect  facility,  it  appears  to  me  that  the  caloric  should 
be  absorbed  by  the  mercury  as  rapidly  as  this  metal  could  be  made  to  en- 
croach upon  the  space  occupied  by  the  calorific  particles,  and  that,  conse- 
quently, no  palpable  condensation  of  them  could  be  effected  by  the  above 
described  process  resorted  to  by  Gay  Lussac. 

258.  Admitting  that,  for  equal  weights,  the  specific  heat  of  air  is  seven 
times  as  great  as  that  of  mercury,  that  of  space  being  the  same  by  the 
premises,  there  could  not  have  been  a  capacity  greater  than  that  of  about 
200  grains  of  the  metal,  whereas  a  very  small  stratum  of  this  metal,  equal 
to  one-fourth  of  an  inch,  would,  in  the  apparatus  employed,  amount  to  more 
than  a  pound. 

259.  The  following  experiments  appear  to  me  to  be  irreconcilable  with 
the  idea  that  the  heat  acquired  by  air  entering  a  space  does  not  arise  from 
the  specific  heat  of  the  space.     When  a  receiver  was  exhausted  so  as  to 
reduce  the  interior  pressure  to  one-fourth  of  that  of  the  atmosphere,  and 
one-fourth  was  suddenly  admitted,  so  as  to  lower  the  mercurial  column  in  a 
gauge  from  about  22^  inches  to  15  inches,  heat  was  produced ;  and  however 
the  ratio  of  the  entering  air  to  the  residual  portion  was  varied,  still  there 
was  a  similar  result. 

260.  When  the  cavity  of  the  receiver  was  supplied  with  the  vapour  of 
ether,  or  with  that  of  water,  so  as  to  form,  according  to  the  Daltonian  hy- 
pothesis, a  vacuum  for  the  admitted  air,  still  heat  was  produced  by  the  lat- 
ter, however  small  might  be  the  quantity,  or  rapid  the  readmission.    When 
the  receiver  was  exhausted,  until  the  tension  was  less  than  that  of  aqueous 
vapour  at  the  existing  temperature,  so  as  to  cause  the  water  to  boil,  as  in 
the  Cryophorus,  or  Leslie's  experiment,  still  the  entrance  of  T^-  of  the 
quantity  requisite  to  fill  the  receiver  caused  the  thermometer  to  rise  a  tenth 


CALORIC. 


47 


of  a  degree.  An  alternate  motion  of  the  key  of  the  cock,  through  one-fourth 
of  a  circle,  within  one-third  of  a  second  of  time,  was  adequate  to  produce 
the  change  last  mentioned. 

261.  The  fact,  that  heat  is  produced,  when  to  air,  rarefied  to  one-fourth 
of  the  atmospheric  density,  another  fourth  is  added,  seems  to  me  to  be  irre- 
concilable with  the  idea,  that  this  result  arises  from  the  compression  of 
the  portion  of  air  previously  occupying  the  cavity,  since  the  entering  air 
must  be  as  much  expanded  as  the  residual  portion  is  condensed. 

262.  As,  agreeably  to  Dalton,  a  cavity  occupied  by  a  vapour  acts  as  a 
vacuum  to  any  air  which  may  be  introduced,  I  infer  that  when  a  receiver, 
after  being  supplied  with  ether  or  water,  is  exhausted  so  as  to  remove  all 
the  air,  and  leave  nothing  besides  aqueous  or  ethereal  vapour,  the  heat,  ac- 
quired by  air  admitted,  cannot  be  ascribed,  consistently,  to  the  condensa- 
tion of  the  vapour. 

263.  It  was  ascertained  by  De  la  Rive  and  Marcet,  that  when  the  bulb 
of  a  thermometer  is  subjected  to  a  jet  of  air  while  entering  an  exhausted 
receiver,  that  the  instrument  shows  that  refrigeration  takes  place.     But  if 
the  jet  be  allowed  to  continue,' a  rise  of  temperature  ensues.     Hence  it  was 
inferred  by  them,  that  in  the  first  instance  there  is  refrigeration,  and  a  con- 
sequent absorption  of  caloric ;  and  subsequently  an  evolution  of  this  prin- 
ciple, in  consequence  of  the  condensation  of  the  air,  which  at  the  first 
moment  of  its  influx,  had  been  refrigerated.    It  appears  to  me,  nevertheless, 
that  in  my  experiments  above  described,  the  effect  upon  the  thermometer 
was  too  rapid,  and  the  quantity  of  the  entering  air  too  minute,  to  allow  it 
to  be  refrigerated  by  rarefaction  in  the  first  place,  and  yet  afterwards  to  be 
so  much  condensed  as  to  become  warm  by  the  evolution  of  caloric. 

OF  THE  SLOW  COMMUN [CATION  OF  HEAT,  COMPRISING  THE 
CONDUCTING  PROCESS  AND  CIRCULATION. 

Of  the  Conducting  Process  in  Solids. 

264.  It  is  well  known  that  if  one  end  of  a  piece  of 
metallic  wire,  as  a  common  pin  for  instance,  be  held  in  a 
candle  flame,  the  other  end  soon  becomes  too  hot  for  the 
fingers.     It  is  also  known  that  the  heated  irons,  used  in 
soldering  and  other  processes  in  the  arts,  have  usually 
wooden  handles,  which  do  not  become  unpleasantly  warm, 
when  the  irons  within  them  are  hot  enough  to  blister  the 
hands.     This  inferior  power  of  wood  in  conducting  heat 
is  also  well  exemplified  by  the  handles  of  silver  tea-pots, 
which  are  sometimes  altogether  of  wood;  in  other  in- 
stances principally  of  metal,  small  portions  of  wood  inter- 
vening.    In  either  case,  the  facility  with  which  the  heat  is 
propagated  in  the  comparatively  thin  metallic  socket,  is 
strongly  contrasted  with  the  difficulty  which  it  experiences 
in  permeating  the  wood. 

265.  An  inferiority  of  conducting  power,  when  com- 
pared with  metals,  is  also  displayed  by  common  bone, 
whalebone,  ivory,  porcelain,  and  especially  glass. 


48  IMPONDERABLE  SUBSTANCES. 

Inequality  of  Conducting  Power,  experimentally  illustrated. 

266.  Let  there  be  four  rods,  severally 
of  metal,  wood,  glass,  and  whalebone,  each 
cemented  into  a  ball  of  sealing-wax.     Let 
each  rod,  at  the  end  which  is  not  cemented 
to  the  wax,  be  successively  exposed  to  the 
flame  excited  by  a  blow  pipe.     It  will  be 
found,  that  the  metal  becomes  quickly  heat- 
ed throughout,  so  as  to  fall  off  from   the 
wax;  but  the  wood  or  whalebone  may  be 
destroyed,  and  the  glass  bent  by  the  igni- 
tion, very  near  to  the  wax,  without  melting 
it  so  as  to  liberate  them. 

Additional  Illustration. 

267.  The  following  method  of  illustrat- 
ing the  diversity  of  conducting  power,  pos- 
sessed   by    different   substances,    has   been 
suggested  by  an  analogous  process  described 
in  Silliman's  Chemistry. 

268.  Rods  similar  in  diameter  and  length,  and  consisting  severally  of 
lead,  tin,  iron,  copper,  wood,  and  ivory,  are  made  to  pass  from  side  to  side, 
through  a  vessel  of  sheet  copper,  in  the  shape  of  an  oblong  parallelepiped. 
Each  rod  extends  on  one  of  the  sides,  to  an  equal  distance  beyond  the  ves- 
sel.    By  these  means,  when  the  vessel  is  filled  with  boiling  water,  equal 
portions  of  each  rod  being  situated  within  the  boiler,  they  are  all  exposed  to 
an  equal  degree  of  heat.     It  is  presumed  that  under  these  circumstances  the 
conducting  power  will  be  nearly  in  the  inverse  ratio  of  the  time  necessary 
to  communicate  to  the  equidistant  ends  of  the  rods,  a  heat  adequate  to  cause 
the  ignition  of  similar  pieces  of  phosphorus,  simultaneously  placed   upon 
them,  before  the  application  of  the  boiling  water. 

Rationale  of  the  Fracture  of  Glass  or  Porcelain  by  Heat. 

269.  The  fracture  of  glass  or  porcelain,  exposed  to  fire,  is  the  conse- 
quence of  an  inferior  conducting  power;  as  the  heat  is  not  distributed  with 
quickness  enough  to  produce  a  uniform  expansion.     Hence  glass  is  as  liable 
to  crack  by  heal,  in  proportion  as  it  is  thinner.     It  may  be  divided  by  a 
heated  iron,  by  a  string  steeped  in  oil  of  turpentine  and  inflamed,  or  by  the 
heat  generated  by  friction.  (322,  &c.) 

Of  the  Conducting  Power  of  various  Metals. 

270.  Metals  are  by  far  the  best  conductors  of  caloric.     There  are,  how- 
ever, scarcely  two  that  conduct  it  equally  well. 

271.  Despretz  has  ascertained  by  exact  experiments,  that  the  conduct- 
ing power  of  the  following  metals  is  in  the  ratio  of  the  subjoined  numbers. 

Gold,  -         -  " 1000.0 

Silver,  973.0 

Copper,  -  898.0 

Platinum,  -  381.0 

Iron,  -  374.3 

Zinc, 363.0 


CALORIC. 


49 


Tin, 
Lead, 


303.9 
179.6 


Explanation  of  the  Process  by  which  Heat  is  supposed  to  be  communi- 
cated in  Solids. 

272.  I  conceive  that  in  solids,  the  stratum  of  atoms  forming  the  surface  first 
exposed  to  the  heat,  combining  with  an  excess  of  this  principle,  divides  it 
with  the  next  stratum.     The  caloric  received  by  the  second  stratum,  is  in 
the  next  place  divided  between  the  second  and  third  stratum.     In  the  mean 
lime  the  first  stratum  has  received  an  additional  supply  of  caloric,  which 
passes  to  the  second  and  third  stratum  as  in  the  first  instance;  while  the 
quantity,  at  first  received  by  them,  is  penetrating  further  into  the  mass. 

273.  It  is  I  trust  easy  to  conceive  that,  by  the  process  thus  suggested,  ca- 
loric may  find  its  way  throughout  any  body,  for  the  particles  of  which  it 
may  have  sufficient  affinity.     Probably  the  superior  conducting  power  of 
metals  is  due  in  great  measure  to  a  proportionably  energetic  affinity  for 
caloric. 

274.  The  conjectures,  which  I  ventured  to  advance  respecting  the  mode 
in  which  caloric  may  exist  in  atmospheres  about  atoms,  seem  to  be  pecu- 
liarly applicable  to  the  case  of  metals,  on  account  of  their  great  expansi- 
bility by  heat,  and  susceptibility  of  contraction  by  cold.  (174.) 

275.  If  caloric  be  not  interposed  in  a  dense  repulsive  atmosphere  between 
metallic  atoms,  how  can  its  removal  cause  that  approximation  of  those  atoms 
towards  each  other,  without  which  the  diminution  of  bulk  invariably  conse- 
quent to  refrigeration  could  not  ensue? 

Liquids  almost  destitute  of  Conducting  Power. 

276.  That  liquids  are  almost  devoid  of  power 
to  conduct  heat,  is  proved  by  the  inflammation 
of  ether  over  the  bulb  of  an  air  thermometer, 
protected  only  by  a  thin  stratum  of  water. 

277.  The  inflammation  of  ether  upon  the  sur- 
face of  water,  as  represented  in  this  figure,  does 
not  cause  any  movement  in  the  liquid  included 
in  the  bore  of  the  air  thermometer  at  L,  although 
the  bulb  is  within  a  quarter  of  an  inch  of  the 
flame.     Yet  the  thermometer  may  be  so  sensi- 
tive, that  touching  the  bulb,  while  under  water, 
with  the  fingers,  may  cause  a  very  perceptible 
indication  of  increased  temperature.     By  placing 
the  sliding  index,  I,  directly  opposite  the  end  of 
the  column  of  liquid  in  the  stem  of  the  thermo- 
meter, before  the  ether  is  inflamed,  it  may  be  ac- 
curately discovered  whether  the  heat  of  the  flame 
causes  any  movement  in  it. 


50 


IMPONDERABLE  SUBSTANCES. 


H 


Communication  of  Caloric  by  Circulation. 

278.  That  caloric  cannot  be  communicated  in  liquids,  unless  it  be  so  ap- 
plied as  to  cause  a  circulation  of  the   particles,  is   demonstrated  by  the 
following  experiment. 

279.  A  glass  jar,  about  30  inches  in  height,  is  supplied  with  as  much 
water  as  will  rise  in  it  within  a  few  inches  of  the  brim.     By  means  of  a 
tube  descending  to  the  bottom,  a  small  quantity  of  blue  colouring  matter  is 
introduced  below  the  colourless  water  so  as  to  form  a  stratum  as  represented 
at  A,  in  the  engraving.     A  stratum,   differently  coloured,  is  formed  in  the 
upper  part  of  the  vessel,  as  represented  at  B.     A  tin  cap,  supporting  a 
hollow  tin  cylinder,  closed  at  bottom,  and  about  an  inch  less  in  diameter 

than  the  jar,  is  next  placed  as  it  is  seen 
in  the  engraving,  so  that  the  cylinder 
may  be  concentric  with  the  jar,  and 
descend  about  3  or  4  inches  into  the 
water. 

280.  The  apparatus  being  thus  pre- 
pared, if  an  iron  heater,  H,  while  red- 
hot,  be  placed  within  the  tin  cylinder, 
the  coloured  water,  about  it,  soon  boils ; 
yet  neither  of  the  coloured  strata  inter- 
mingles with  the  intermediate  colourless 
mass;    and   on  sliding  the   finger  up- 
wards, while  in  contact  with  the  glass, 
the  heat  will  be  found  to  have  penetrated 
only  a  very  small  distance  below  the 
tin  cylinder.      But  if  the  ring,  R,   be 
placed,   while   red-hot,    upon   the   iron 
stand  which  surrounds  the  jar  at  S  S, 
the  portion  of  the  liquid  coloured  blue, 
being   opposite   to   the   ring,   will   rise 
until  it  encounters  the  warmer,  and  of 
course    lighter,   particles,   which    have 
been  in  contact  with  the  tin  cylinder. 
Here  its  progress  upwards  is  arrested; 
and,  in  consequence  of  the  diversity  of 
the  colours,  a  well  defined  line  of  sepa- 
ration becomes  conspicuous. 

281.  The  phenomena  of  this  interest- 
ing experiment  may  be  thus  explained. 

282.  If  the  upper  portion  of  a  vessel, 
1  containing  a  fluid,  be  heated  exclusive- 
ly, the   neighbouring   particles   of  the 
fluid  being  rendered  lighter  by  expan- 


R 


sion,  are  more  indisposed,  than  before,  to  descend  from  their  position.  But 
if  the  particles,  forming  the  inferior  strata  of  the  fluid  in  the  same  vessel-,  be 
rendered  warmer  than  those  above  them,  their  consequent  expansion  and 


CALORIC. 


51 


diminution  of  specific  gravity  causes  them  to  give  place  to  particles  above 
them,  which  not  being  as  warm,  are  heavier.  Hence  heat  must  be  ap- 
plied principally  to  the  lower  part  of  the  vessel,  in  order  to  occasion  a  uni- 
form rise  of  temperature  in  a  contained  fluid. 

283.  This  statement  is  equally  true,  whether  the  fluid  be  aeriform  or 
liquid,  excepting  that  in  the  case  of  aeriform  fluids,  the  influence  of  pres- 
sure on  their  elasticity 'may  sometimes  co-operate  with,  and  at  others  op- 
pose, the  influence  of  temperature. 

Experimental  Illustration  of  the  Process  by  which  Caloric  is  distributed 
in  a  Liquid  until  it  boils. 

284.  On  the  first  application  of  heat 
to  the  bottom  of  a  vessel  contain- 
ing cold  water,  the  particles  in  con- 
tact with  the  bottom  are  heated  and 
expanded,  and  consequently  become 
lighter  than  those  above  them.  They 
rise  therefore,  giving  an  opportunity 
to  other  particles  to  be  heated  and 
to  rise  in  their  turn.  The  particles 
which  were  first  heated,  are  soon 
comparatively  colder  than  those  by 
which  they  were  displaced,  and,  de- 
scending to  their  primitive  situation, 
are  again  made  to  rise  by  additional 
heat  and  enlargement  of  their  bulk. 
Thus  the  temperatures  reversing  the 
situations,  and  the  situations  the  tem- 
peratures, an  incessant  circulation  is 
maintained,  so  long  as  any  one  por- 
tion of  the  liquid  is  cooler  than 
another,  or  in  other  words,  till  ebul- 
lition takes  place;  previously  to  which  every  particle  must  have  combined 
with  as  much  caloric  as  it  can  receive,  without  being  converted  into  steam. 

285.  The  manner  in  which  caloric  is  distributed  throughout  liquids  by 
circulation,  as  above  described,  is  illustrated  advantageously  by  an  experi- 
ment contrived  by  Rumford,  who  first  gave  to  the  process  the  attention 
which  it  deserves. 

286.  Into  a  glass  nearly  full  of  water,  as  represented  by  the  foregoing 
figure,  small  pieces  of  amber  are  introduced,  which  are  in  specific  gravity 
so  nearly  equal  to  water,  as  to  be  little  influenced  by  gravitation.*     The 
lowermost  part  of  the  vessel  being  subjected  to  heat  while  thus  prepared, 
the  pieces  of  amber  are  seen  rising  vertically  in  its  axis,  and  after  they 
reach  the  surface  of  the  liquid,  moving  towards  the  sides,  where  the  vessel 
is  colder  from  the  influence  of  the  external  air.     Having  reached  the  sides 
of  the  vessel,  they  sink  to  the  bottom,  whence  they  are  again  made  to  rise 
as  before.     While  one  set  of  the  pieces  of  amber  are  at  the  bottom  of  the 
liquid,  some  are  at  the  top,  and  others  at  intermediate  situations ;  thus  de- 


*  As  amber  is  rather  heavier  than  water,  it  is  expedient  to  add  some  sulphate  of 
soda*  to  increase  the  specific  gravity  of  the  liquid. 


52  IMPONDERABLE  SUBSTANCES. 

monstraling  the  movements  by  which  an  equalization  of  temperature  is  ac- 
complished in  liquids. 

287.  When  the  boiling  point  is  almost  attained,  the  particles  being  near- 
ly of  the  same  temperature,  the  circulation  is  retarded.     Under  these  cir- 
cumstances, the  portions  of  liquid  which  are  in  contact  with  the  heated  sur- 
face of  the  boiler  are  converted  into  steam,  before, they  can  be  succeeded 
by  others ;  but  the  steam  thus  produced  cannot  rise  far  before  it  is  con- 
densed.    Hence  the  vibration  and  singing  sound  which  is  at  this  time  ob- 
served. 

288.  According  to  an  observation  of  Gay-Lussac,  water  boils  in  metal- 
lic vessels  at  a  temperature  nearly  two  and  a  half  degrees  lower  than  in 
those  of  earthenware. 

QUICK  COMMUNICATION  OF  HEAT,  OR  RADIATION. 

289.  It  must  be  evident  that  the  heat  which  we  receive 
from  a  fire  in  opposition  to  the  draught,  reaches  us  nei- 
ther by  the  conducting  process  nor  by  circulation.    Actual 
contact  is  evidently  indispensable  to  the  passage  of  heat  in 
either  of  these  modes.     The  aeriform  matter  which  is  in 
contact  with  the  embers,  or  the  blaze  of  a  fire,  forms  part 
of  a  current  which  tends  rapidly  towards  the  flue,  as  must 
be  evident  from  the  celerity  with  which  the  sparks  which 
accompany  it  are  propelled.     The  rapidity  with  which  the 
aerial  particles,  heated  by  the  fire,  are  thus  carried  up  the 
chimney,  far  exceeds  that  with  which  caloric  can  be  com- 
municated, in  the  opposite  direction,  either  by  the  conduct- 
ing process  or  by  circulation. 

290.  The  caloric  received  from  a  fire  under  the  circum- 
stances above  mentioned,  and  which  is  analogous  to  that 
by  means  of  which  the  culinary  operations  of  toasting 
and  roasting  are  accomplished,  is  called  radiant  caloric, 
or  more  usually,  radiant  heat.     It  has  been  called  radiant, 
because  it  appears  "to  emanate  in  radii  or  rays  from  every 
hot  or  even  warm  body,  as  light  emanates  from  luminous 
bodies. 

291.  Radiant  heat  resembles  light  also  in  its  susceptibi- 
lity of  being  reflected  by  bright  metallic  surfaces;  in  which 
case  it  obeys  the  same  laws  as  light,  and  is  of  course  lia- 
ble, in  like  manner,  to  be  collected  into  a  focus  by  concave 
mirrors. 


Phosphorus  ignited  by  Radiant  Heat. 


(Page  53.) 


CALORIC. 


53 


Model  for  illustrating  the  Operation  of  Concave  Mirrors. 


292.  The  object  of  the  model  represented  by  this  diagram,  is  to  explain 
the  mode  in  which  two  mirrors  operate  in  collecting  the  rays  of  radiant 
heat  emitted  from  one  focus,  and  in  concentrating  them  in  another. 

293.  The  caloric  emitted  by  a  heated  body  in  the  focus  of  the  mirror, 
A,  would  pass  off  in  radii  or  rays,  lessening  in  intensity  as  the  space  into 
which  they  pass  enlarges ;  or,  in  other  words,  as  the  squares  of  the  dis- 
tances.    But  those  rays  which  are  arrested  by  the  mirror,  are  reflected 
from  it  in  directions  parallel  to  its  axis.*     Being  thus  corrected  of  their 
divergency,  they  may  be  received,  without  any  other  loss  than  such  as  arises 
from  mechanical  imperfections,  by  the  other  mirror,  which  should  be  so 
placed  that  the  axis  of  the  two  mirrors  may  be  coincident ;  or,  in  other 
words,  so  that  a  line  drawn  through  their  centres,  from  A  to  B,  may  at  the 
same  time  pass  through  their  foci,  represented  by  the  little  balls  supported 
by  the  wires,  W  W. 

294.  The  second  mirror,  B,  reflects  to  its  focus  the  rays  which  reach  it 
from  the  first;  for  it  is  the  property  of  a  mirror,  duly  concave,  to  render 
parallel  the  divergent  rays  received  from  its  focus,  and  to  cause  the  parallel 
rays  which  it  intercepts  to  become  convergent,  so  as  to  meet  in  its  focus. 

295.  The  strings  in  the  model  are  intended  to  represent  the  paths  in 
which  the  rays  move,  whether  divergent,  parallel,  or  convergent. 

Phosphorus  ignited  at  the  distance  of  sixty  feet  by  an  incandescent 

Iron  Ball. 

296.  The  opposite  engraving  represents  the  mirrors  which  I  employ  in 
the  ignition  of  phosphorus  and  lighting  a  candle  by  an  incandescent  iron 
ball.     I  have  produced  this  result  at  sixty  feet,  and  it  might  be  always  ef- 
fected at  that  distance,  were  it  not  for  the  difficulty  of  adjusting  the  foci  with 
sufficient  accuracy  and  expedition.     I  once  ascertained  that  a  mercurial 
thermometer,  when  at  the  distance  last  mentioned,  rose  to  110  degrees  of 
Fahrenheit. 

297.  A  tallow  candle  is  so  situated,  that  its  wick,  previously  imbued  with 
phosphorus,  may  be  in  the  fpcus  of  one  of  the  mirrors.     A  lamp  being 
similarly  situated  with  respect  to  the  other  mirror,  it  will  be  easy,  by  re- 
ceiving the  focal  image  of  the  flame  on  any  small  screen,  so  to  alter  the 
arrangement,  as  to  cause  this  image  to  fall  upon  the  phosphorus.     This 
being  effected,  the  screen,  S,  placed  between  the  mirrors,  is  lowered  so  as 

The  axis  of  a  mirror  is  in  a  line  drawn  from  its  centre  through  its  true  focus. 


54 


IMPONDERABLE  SUBSTANCES. 


to  intercept  the  rays.  The  iron  ball  being  rendered  white-hot  is  now  sub- 
stituted for  the  lamp,  and  the  screen  being  lifted,  the  phosphorus  takes  fire 
and  the  candle  is  lighted. 

Of  the  Diversity  of  Radiating  Power  in  Metals,  Wood,  Charcoal, 
Glass,  Pottery,  fyc. 

Diversity  of  Radiating  Power  experimentally  illustrated. 


298.  At  M,  (see  figure,)  a  parabolic  mirror  is  represented.     At  B  is 
a  square  glass  bottle,  one  side  of  which  is  covered  with  tin  foil,  and 
another  so  smoked  by  means  of  a  lamp  as  to  be  covered  with  carbon.    Be- 
tween the  bottle  and  mirror,  and  in  the  focus  of  the  latter,  there  is  a  bulb 
of  a  differential  thermometer,  protected  from  receiving  any  rays  directly 
from  the  bottle  by  a  small  metallic  disk.     The  bottle  being  filled  with  boil- 
ing water,  it  will  be  found  that  the  temperature  in  the  focus,  as  indicated  by 
the  thermometer,  is  greatest  when  the  blackened  surface  is  opposite  to  the 
mirror,  and  least  when  the  tin  foil  is  so  situated ;  the  effect  of  the  naked 
glass  being  greater  than  the  one,  and  less  than  the  other. 

299.  The  worst  radiators  are  the  best  rejectors,  and  the  best  radiators 
are  the  worst  reflectors  ;  since  the  arrangement  of  particles  ivhich  is  fa- 
vourable for  radiation  is  unfavourable  for  reflection,  and  vice  versa. 

300.  A  polished  brass  andiron  does  not  become  hot  when  exposed  from 
morning  till  night  to  a  fire,  so  near  that  the  hand  placed  on  it  is  scorched 
intolerably  in  a  few  seconds.     Fire  places  should  be  constructed  of  a  form 
and  materials  to  favour  radiation:  flues,  of  materials  to  favour  the  con- 
ducting process.     To  preserve  heat  in  air  or  to  refrigerate  in  water,  vessels 
should  be  made  of  bright  metal.     In  the  latter  case,  the  brightness  is  bene- 
ficial, only  because  the  surface  cannot  be  bright  without  being  clean.     If 
soiled,  its  communication  with  the  liquid  would  be  impeded. 

301.  Rationale. — Metals  appear  to  consist  of  particles  so  united  with  each 
other,  or  with  caloric,  as  to  leave  no  pores  through  which  radiant  caloric 
can  be  projected.     Hence  the  only  portion  of  any  metallic  mass  which  can 
yield  up  its  rays  by  radiation  is  the  external  stratum. 


CALORIC.  55 

302.  On  the  other  hand,  from  its  porosity,  and  probably  also  from  its  not 
retaining  caloric  within  its  pores  tenaciously  as  an  ingredient  in  its  compo- 
sition, charcoal  opposes  but  little  obstruction  to  the  passage  of  that  subtile 
principle,  when  in  the  radiant  form ;  and  hence  its  particles  may  all  be 
simultaneously  engaged  in  radiating  any  excess  of  this  principle  with  which 
a  feeble  affinity  may  have  caused  them  to  be  transiently  united,  or  in  re- 
ceiving the  rays  emitted  by  any  heated  body,  to  the  emanations  from  which 
they  may  have  been  exposed.     We  may  account  in  like  manner  for  the 
great  radiating  power  of  earthenware  and  wood. 

303.  For  the  same  reason  that  calorific  rays  cannot  be  projected  from  the 
interior  of  a  metal,  they  cannot  enter  it  when  projected   against  it  from 
without.     On  the  contrary,  they  are  repelled  with  such  force  as  to  be  re- 
flected without  any  perceptible  diminution  of  velocity.     Hence  the  superior 
efficacy  of  metallic  reflectors. 

304.  It  would  seem  as  if  the  calorific  particles  which  are  condensed  be- 
tween those  of  the  metal,  repel  any  other  particles  of  their  own  nature  which 
may  radiate  towards  the  metallic  superficies,  before  actual  contact  ensues; 
otherwise,  on  account  of  mechanical  imperfection,  easily  discernible  with 
the  aid  of  a  microscope,  mirrors  could  not  be  as  efficacious  as  they  are 
found  to  be  in  concentrating  radiant  heat.     Their  influence,  in  this  respect, 
seems  to  result  from  the  excellence  of  their  general  contour,  and  is  not  pro- 
portionably  impaired  by  numberless  minute  imperfections. 

Radiation  of  Cold. 

305.  A  thermometer  placed  in  the  focus  of  a  mirror  indicates  a  decline  of 
temperature,  in  consequence  of  a  mass  of  ice  or  snow  being  placed  before 
it  in  the  situation  occupied  by  the  bottle  in  the  preceding  figure.     This 
change  of  temperature  has  been  considered  as  demonstrating  the  radiation, 
and  consequently  the  materiality  of  cold.     For  since  the  transfer  of  heat 
by  radiation  has  been  adduced  as  a  proof  of  the  existence  of  a  material 
cause  of  heat,  it  is  alleged  that  the  transmission  of  cold  by  the  same  pro- 
cess ought  to  be  admitted  as  equally  good  evidence  of  a  material  cause  of 
cold. 

306.  The  following  is  the  explanation  which  I  give  of  this  phenomenon, 
agreeably  to  the  opinion  that  cold  is  diminished  heat. 

307.  I  suppose  that  caloric  exists  throughout  the  sublunary  creation,  as 
an  atmosphere  held  to  the  earth  by  the  general  attraction  of  all  the  matter 
in  it,  being  in  part  combined  with  bodies  in  proportion  to  their  affinities  or 
capacities  for  it,  and  partly  free.     The  particles  of  the  free  caloric  I  sup- 
pose incessantly  to  exert  a  self-repellent  power,  which  increases  with  its 
density,  as  in  the  case  of  aeriform  fluids.     The  repulsive  power  of  caloric 
being  in  the  ratio  of  the  quantity,  it  follows  that  either  a  diminution  or  in- 
crease of  temperature  in  any  spot  must  equally  produce  a  movement  in 
the  calorific  particles ;  in  the  one  case  from  the  spot  which  sustains  the 
change,  in  the  other  towards  it. 

308.  Supposing  the  surface  of  a  mirror  to  be  subjected  to  the  influence  of 
a  space  in  which  a  diminution  of  temperature  has  been  produced,  the  rows 
of  calorific  particles  between  the  mirror  and  the  space  will  move  into  the 
space.     The  removal  of  one  set  of  the  calorific  particles  from  the  surface 
of  the  mirror,  must  make  room  for  another  set  to  flow  into  the  situations 
thus  vacated.     The  curvature  of  the  surface  of  the  mirror  renders  it  more 
easy  for  those  particles  to  succeed  which  lie  in  the  direction  of  the  focus. 


56  IMPONDERABLE  SUBSTANCES. 

Of  the  Observations  and  Apparatus  of  Melloni. 

309.  By  means  of  a  thermo-electric  pile,  and  a  galvanoscope  or  multi- 
plier, of  extreme  delicacy,  Melloni  has  lately  ascertained  some  interesting 
properties  of  heat-producing  rays,  which  serve  to  show  a  marked  difference, 
and,  at  the  same  time,  a  great  analogy  between  them  and  the  rays  of  light. 

310.  Let  there  be  provided  three  transparent  plates,  severally  of  alum, 
rock  salt,  and  rock  crystal  or  glass,  each  about  an  eighth  or  tenth  of  an 
inch  thick;  it  will  be  found  that  the  effect  of  the  transmitted  rays  upon  the 
pile,  when  unimpeded,  being  30,  that  which  takes  place  during  the  inter- 
position of  the  rock  salt,  will  be  28,  during  the  interposition  of  the  rock 
crystal  15  or  16  ;  while  during  the  interposition  of  the  alum  the  effect  will 
only  be  two  or  three. 

311.  The  effect  of  interposing  a  plate  of  smoky  rock  crystal,  will,  under 
the  same  circumstances,  be  equal  to  14  or  15. 

312.  In  other  words,  out  of  30  parts,  rock  salt  intercepts  two  parfs  of 
the  influence  of  the  radiant  heat;  rock  crystal,  whether  smoky  or  clear,  in- 
tercepts about  half;  while  alum,  or  glass,  intercepts  nearly  the  whole. 

313.  If,  in  like  manner,  two  pairs  of  plates  be  employed,  one  pair  formed 
of  a  pane  of  green  glass  (impermeable  to  red  rays,)  and  a  plate  of  alum ; 
the  other  pair  formed  of  a  pane  of  perfectly  opake  black  glass,  coupled 
with  a  plate  of  rock  salt,  it  will  be  found  that  the  first  mentioned  pair  in- 
tercepts the  calorific  radiation  entirely,  while  the  other  permits  nearly  one- 
third  as  much  to  pass,  as  when  not  interposed. 

314.  Hence  it  appears,  that  bodies,  quite  permeable  by  light,  may  en- 
tirely intercept  radiant  heat,  while  others,  impermeable  by  light,  allow  the 
passage  of  radiant  heat.    Melloni  designates  the  former  as  athermane,  the 
latter  as  diathermane  bodies. 

315.  It  follows  that  permeability  to  heat-producing  rays  is  not  to  be 
confounded  with  transparency. 

316.  Radiant  heat  has  been  found  by  Melloni  to  vary  in  its  power  of 
permeating  bodies,  according  to  the  source  from  which  it  proceeds,  and  the 
media  through  which  it  may  have  passed.     After  passing  through  nitric 
acid,  more  will  pass  through  alum  than  if  received  directly  from  the  source. 

317.  Moreover  certain  media  have,  with  respect  to  calorific  rays,  an  in- 
fluence analogous  to  that  which  coloured  media  have  with  respect  to  light, 
in  allowing  some  rays  to  pass,  while  others  are  arrested. 

318.  This  property  of  the  diathermane  bodies,  is  called  diathermansie. 
Rock  salt  seems  to  be  a  diathermane  body,  devoid  of  diathermansie.     The 
last  mentioned  property  lessens  as  the  body  is  thinner,  and  may,  as  in  the 
case  of  coloured  media,  be  rendered  null  by  an  extreme  tenuity. 

319.  The  non-luminous  calorific  rays  have  been  ascertained  by  Melloni, 
to  be  susceptible  of  refractions  analogous  to  those  of  light.     When  the 
thermo-electric  pile  is  so  situated  as  that  the  rays  of  heat  cannot  directly 
reach  it,  by  interposing  a  prism  of  rock  salt,  having  a  refracting  angle  of 
60°,  the  rays  will  be  made  to  reach  the  pile. 

320.  From  experiments  performed  by  Prof.  Forbes,  of  Edinburg,  with 
the  aid  of  Melloni's  thermoscope,  above  alluded  to,  it  appears  that  radiant 
heat,  unaccompanied  by  light-producing  rays,  is  susceptible  of  polariza- 
tion.    Respecting  this  fact,  some  further  mention  will  be  made  in  treating 
of  the  polarization  of  light. 


CALORIC.  57 

MEANS  OF  PRODUCING  HEAT,  OR  RENDERING  CALORIC 
SENSIBLE. 

Of  the  Solar  Rays  as  a  Source  of  Heat. 

321.  Of  all  the  natural  sources  of  heat,  the  sun  is  ob- 
viously the  most  prolific. 

322.  The  solar  rays  may  be  collected  into  a  focus  either 
by  the  refracting  influence  of  glasses  or  the  reflecting 
power  of  mirrors.     They  may  be  converged  by  reflection, 
in  a  mode  analogous  to  that  illustrated  in  the  case  of 
radiant  heat. 

323.  The  glasses  employed  for  concentrating  light  are 
called  lenses  from  their  shape,  which  is  that  of  a  double 
convex  lens. 

324.  As  the  intensity  of  the  heat  produced  by  the  solar 
beams  is  in  proportion  to  the  quantity  of  them  which  may 
be  collected  upon  any  given  spot,  there  appears  to  be  no 
limit  to  the  degree  of  heat  producible  by  their  concentra- 
tion, excepting  that  arising  from  the  difficulty  of  making 
lenses  sufficiently  large  and  free  from  defect,  or  of  associ- 
ating mirrors  sufficiently  numerous  and  well  arranged. 

325.  Until  lately,  scarcely  any  occurrence  of  antiquity 
appeared  more  unaccountable  than  the  destruction  of  the 
Roman  ships,  which  Archimedes  is  alleged  to  have  accom- 
plished, by  concentrating  upon  them  the  rays  of  the  sun. 
Nevertheless,  of  this  wonderful  feat,  Buffon  seems  to  have 
discovered  the  means.    Having  arranged  a  number  of  plane 
mirrors  so  as  to  concur  in  reflecting  the  solar  image  upon 
the  same  spot,  he  was  enabled  to  fuse  lead  at  a  distance 
of  140  feet.     This  contrivance  resembles  that  which  Ar- 
chimedes employed,  if  we  may  judge  from  the  accounts 
which  have  been  given  of  the  latter.     Previously  to  the 
employment  of  pure  oxygen  gas,  the  hydro-oxygen  blow- 
pipe, and  voltaic  electricity,  there  was  no  known  mode  of 
rivalling  the  heat  produced  by  large  burning-glasses  and 
mirrors. 

Sensible  Heat  evolved  by  Electricity. 

326.  The  power  of  lightning  to  produce  ignition  is  dis- 
played by  the  conflagration  of  ships  and  barns,  in  con- 
sequence of  the  ignition  of  cotton,  hay,  or  other  combus- 
tibles.   The  power  of  the  electric  spark  to  ignite  an  inflam- 

8 


58 


IMPONDERABLE  SUBSTANCES. 


mable  gaseous  mixture  is  agreeably  illustrated,  by  means 
of  the  apparatus  described  in  the  following  article. 

Application  of  an  Electrophorus  to  the  Ignition  of  Hydrogen  Gas,  generated  in  a  Self- 
regulating  Reservoir. 

327.  In  order  that  the  interior  of  this  apparatus  may  be  described,  (see  fig.  be- 
low)  the  side  of  the  box,  B,  below  the  reservoir,  R,  is  supposed  to  be  removed.     On 
the  bottom  of  the  box  is  a  square  metallic  dish  covered  by  a  stratum  of  sealing  wax. 
The  metallic  plate,  D,  is  supported  behind  by  a  glass  rod,  cemented  to  a  socket 
soldered  to  a  hinge.    Upon  this  hinge,  like  the  lid  of  a  trunk,  the  plate  moves  freely, 
while  connected  with  the  lever,  L,  by  a  silken  cord.     The  lever,  L,  is  attached  to 
the  key  of  the  cock,  C  ;  so  that  opening  the  cock  causes  the  plate  to  rise,  and  touch 
the  knob,  n,  of  the  insulated  wire.     This  wire  terminates  just  before  the  orifice  of 
the  tube,  t,  proceeding  from  the  cock,  and  about  one-eighth  of  an  inch  from  another 
wire,  supported  upon  that  tube. 

328.  The  glass  reservoir,  R,  receives  into  its  open  neck,  the  tapering  part  of  a 
glass  vessel,  V,  which  is  so  proportioned,  and  fitted  to  the  neck  by  grinding,  as  to 
make  with  it  an  air-tight  juncture. 

329.  Below  this  juncture,  the  vessel,  V,  converges,  until  it  assumes  the  form  of  a 

tube,  reaching  nearly  to  the  bottom  of 
the  reservoir.  Around  the  tube  thus 
formed,  a  coil  of  zinc  is  supported,  so 
as  to  be  above  the  orifice  of  the  tube, 
constituted  as  abovementioned. 

330.  If  the  reservoir  be  sufficiently 
supplied  with  diluted  sulphuric  acid, 
the  reaction  between  this  solvent  and 
the  zinc  will  evolve  hydrogen  gas.  The 
gas  thus  evolved,  if  not  allowed  to  es- 
cape, will  force  the  liquid  which  ge- 
nerates it  through  the  orifice  of  the 
tube  proceeding  from  the  vessel,  V, 
into  the  cavity  of  this  vessel,  until  the 
quantity  of  the  acid  remaining  below, 
is  insufficient  to  reach  the  zinc.  When- 
ever this  takes  place,  the  evolution  of 
hydrogen  ceases.  As  soon,  however, 
as,  by  opening  the  cock,  any  portion  of 
the  gas  is  allowed  to  escape,  an  equi- 
valent bulk  of  acid  descends  into  the 
reservoir,  and  reacts  with  the  zinc, 
until,  by  the  further  generation  of 
hydrogen,  the  portion  of  acid  which  may  have  descended  shall  again  be  expelled 
from  the  lower  into  the  upper  vessel.  At  the  same  moment  that,  by  turning  the 
cock,  C,  a.  jet  of  gas  is  emitted,  the  plate  of  the  electrophorus  being  lifted  against 
the  knob,  n,  of  the  wire,  an  electrical  spark  will  pass  from  the  other  end  of  this 
wire  to  that  of  the  wire  supported  by  the  cock,  and  of  course  uninsulated  by  its 
communication  with  the  operator's  hand.  Consequently  the  jet  of  hydrogen  will  be 
ignited,  and  will  light  a  candle  exposed  to  its  influence. 

°  331.  For  a  rationale  of  the  electrophorus,  as  also  for  other  exemplifications  of  the 
igniting  power  of  electric  discharges,  I  refer  to  my  treatise  on  statical  or  mechanical 


electricity. 


Ignition  by  Galvanism. 


Galvanic  Apparatus  for  Lighting  a  Lamp. 

332.  The  following  figure  represents  an  instrument  for  lighting  a  lamp  by  means 
of  a  galvanic  discharge  from  a  calorimotor  ;  for  a  more  ample  explanation  of  which 
I  must  refer  the  reader  to  my  lectures  on  galvanism. 

333.  The  plunger,  P,  being  depressed  by  means  of  the  handle  attached  to  it,  some 
acid  contained  in  the  box,  B,  is  displaced,  so  as  to  rise  among  the  galvanic  plates. 
By  the  consequent  evolution  of  the  galvanic  fluid,  a  platinum  wire,  fastened  between 
the  brass  rods  forming  the  poles  of  the  calorimotor,  and  projecting  over  the  lamp  as 
seen  at  R,  is  rendered  white  hot,  and  a  filament  of  the  wick,  previously  laid  upon  it, 
is  inflamed. 


CALORIC. 


59 


334.  The  weight  acts  as  a  counterpoise  to  the  plunger,  and  when  it  is  not  depress- 
ed by  the  hand,  keeps  it  out  of  the  acid. 

Galvano-ignition  Apparatus. 

335.  In  many  of  my  experiments,  for  the  purpose  of 
producing  the  temperature  of  combustion  in  cavities 
inaccessible  by  ordinary  means,  1  employ  a  wire  ig- 
nited by  being  made  a  part  of  a  galvanic  circuit. 

336.  Of  the  apparatus  by  which  this  object  is  effect- 
ed, 1  shall  here  give  a  description  accompanied  by  a 
figure,  which  will  convey  a  general  idea  of  the  con- 
trivance, applicable  to  all  cases  where  it  may  be  used. 
Having  thus  prepared  the  student,  I  shall  in  future  re- 
fer to  it  under  the  name  at  the  head  of  this  article,  in 
order  to  avoid  circumlocution,  and  unnecessary  recur- 
rence to  analogous  description.    D  represents  a  section 
of  a  metallic  disk.     A  B,   two   metallic  rods,  which 
should  be  of  iron,  if  in  contact  with  mercury,  but 
which  otherwise  may  be  of  brass,  are  made  to  enter 
the  cavity.     If,  as  in  general,  the  rods  pass  through  a 
metallic  plate  or  cylinder,  one  of  them  may  be  solder- 
ed to  the  plate  or  cylinder.     The  other  must  be  so  se- 
cured, where  it  passes  through  the  metal,  by  a.  collar 
of  leather,  £,  as   to  insulate  it  from  all  metallic  con- 
tact, and  to  render  the  aperture  through  which  it  en- 
ters,  air-tight  if  necessary.     The  rods  may  extend  into 

the  cavity  to  any  convenient  distance,  their  terminations  being  approximated,  more 
or  less,  as  may  be  desirable,  but  not  brought  in  contact.  To  one  of  these  rods, 
where  it  terminates  within  the  cavity,  one  end  of  a  fine  platinum  wire  is  soldered ; 
the  other  end  of  the  wire  being  soldered  in  like  manner  to  the  similarly  situated  ter- 
mination of  the  other  rod.  To  the  rod  secured  by  the  collar  of  leather,  at  the  termi- 
nation on  the  outside  of  the  cavity,  a  gallows  screw  is  attached,  by  means  of  which 
a  flexible  lead  or  copper  rod  may  be  made  fast  at  one  end,  while  the  other  is  fastened 
to  one  of  the  poles  of  a  competent  calorimotor.  To  the  other  pole  of  the  calorimo- 
tor,  another  rod  is  attached  at  one  end,  which  at  the  other  may  be  secured  by  a  gal- 
lows screw,  either  soldered  to  the  plate,  or  to  the  projecting  extremity  of  the  unin- 
sulated rod,  as  in  the  figure.  Sometimes  the  last  mentioned  rod  is  left  at  liberty,  so 
as  to  be  made  to  touch,  when  desirable,  any  part  of  the  apparatus  having  a  metallic 
communication  with  the  uninsulated  rod.  If,  under  these  circumstances,  the  calo- 
rimotor be  put  in  operation,  the  wire  will  be  ignited. 


60  IMPONDERABLE  SUBSTANCES. 

Ignition  by  Collision. 

337.  The  ignition  of  spunk,  tinder,  or  gunpowder,  by  means  of  flint  and 
steel,  comes  under  this  head.     In  the  rotary  match  box,  the  collision  is 
produced  by  a  wheel  thrown  into  rapid  rotation.     An  analogous  apparatus, 
called  a  steel  mill,  had  long  been  employed  to  procure  light  in  mines  infested 
with  light  carburetted   hydrogen,  prior  to  Sir  H.  Davy's  invention  of  the 
safety  lamp.     This  gas  explodes  on  coming  into  contact  with  the  flame  of 
a  lamp  or  candle,  but  is  not  ignited  by  the  scintillations  from  a  steel  mill. 

Heat  produced  by  Percussion. 

338.  A  rod  of  iron  hammered  with  great  rapidity  by  a  skilful  workman, 
will  become  so  hot  as  to  ignite  a  sulphur  match,  and  phosphorus  may  be 
easily  ignited  in  this  way ;  but  the  same  piece  of  iron  cannot  be  ignited  by 
percussion  more  than  once. 

339.  Coins  grow  hot  when  struck  in  the  coining  press,  but,  if  cooled 
during  each  interval  between  the  blows,  are  less  heated  at  each  successive 
blow.     At  the  same  time  the  density  of  the  mass  is  permanently  increased, 
probably  by  the  expulsion  of  the  caloric,  interposed  between  the  metallic 
atoms.  (272.) 

Heat  produced  by  Friction. 

340.  Friction,  as  a  means  of  producing  heat,  differs  from  percussion ; 
since  in  the  case  of  friction,  the  effect  being  confined  to  the  surfaces  of  bo- 
dies, there  is  no  condensation  of  the  mass  subjected  to  the  process.     Colli- 
sion differs  both  from  percussion  and  friction ;  for  it  produces  ignition  only 
in  the  minute  portions  of  matter  which  are  struck  off.     The  masses  em- 
ployed are  not  heated. 

341.  It  is  well  known  that  savages  avail  themselves  of  the  friction  of 
wood  to  produce  fire.     Wood  revolving  in  the  lathe  may  be  carbonized, 
throughout  the  circle  of  contact,  by  holding  against  it  another  piece  pro- 
perly sharpened.     By  rubbing  one  cork  against  another,  sufficient  heat  is 
produced  to  ignite  phosphorus. 

Glass  so  heated  by  the  Friction  of  a  Cord,  as  to  separate  into  two  parts  on  being  sub- 
jected to  Cold  Water. 

342.  The  process  for  dividing  a  tube,  which  I  am  about  to  describe,  illustrates  at 
once  the  heat  produced  by  friction,  and  the  non-conducting  power  of  glass. 

343.  Some  years  ago,  Mr.  Isaiah  Lukens  showed  me  that  a  small  phial  or  tube 
might  be  separated  into  two  parts,  if  subjected  to  cold  water,  after  having  been  heated 
by  the  friction  of  a  cord  made  to  circulate  about  it,  by  two  persons  alternately  pull- 
ing in  opposite  directions.     I  was  subsequently  enabled  to  employ  this  process  for 
dividing  large  vessels  of  four  or  five  inches  in  diameter;  and  likewise  to  render  it  in 
every  case  more  easy  and  certain,  by  means  of  a  piece  of  plank  forked  like  a  boot- 
jack, as  represented  in  the  following  figure,  and  also  having  a  kerf  or  slit  cut  by  a 
saw,  parallel  to,  and  nearly  equidistant  from,  the  principal  surfaces  of  the  plank,  and 
at  right  angles  to  the  incisions  forming  the  fork. 

344.  By  means  of  the  fork,  the  glass  is  easily  held  steady  by  the  hand  of  one  ope- 
rator. By  means  of  the  kerf,  the  string,  while  circulating  about  the  glass,  is  confined 
to  the  part  where  the  separation  is  desired.  As  soon  as  the  cord  smokes,  the  glass 
is  plunged  into  water,  or  if  too  large  to  be  easily  immersed,  the  water  must  be  thrown 
upon  it.  This  method  is  always  preferable  when  the  glass  vessel  is  so  open,  that, 
on  being  immersed,  the  water  can  reach  the  inner  surface.  As  plunging  is  the 
most  effectual  method  of  employing  the  water,  1  usually,  in  the  case  of  a"  tube,  close 
the  end  which  is  to  be  sunk  in  the  water,  so  as  to  restrict  the  refrigeration  to  the 
outside. 


CALORIC. 


61 


345.  Rationale. — If  the  friction  be  continued  long  enough,  the  glass,  though  a  very 
bad  conductor  of  heat,  becomes  heated  throughout  in  the  part  about  which  the  fric- 
tion takes  place;  of  course  it  is  there  expanded.  While  in  this  state,  being  suddenly 
refrigerated  by  the  cold  water  on  the  outside  only,  the  stratum  of  particles  imme- 
diately affected,  contracts,  while  that  on  the  inside,  not  being  chilled,  undergoes  no 
concomitant  change.  Hence  a  separation  usually  follows :  see  (264,  &c.) 

Ignition  by  Attrition. 

346.  If,  whilst  a  thin  disk  of  sheet  iron  is  made  to  revolve  rapidly  upon 
its  axis  by  means  of  a  lathe,  the  circumference  be  brought  into  contact  with 
a  plate  of  steel,  heat  will  be  so  copiously  evolved  at  the  place  of  collision, 
that  the  steel  may  be  actually  divided  by  the  successive  ignition  and  abra- 
sion of  a  portion  of  its  particles.     The  ignition  is  confined  to  the  steel,  be- 
cause the  heat,  evolved  in  this  case,  is  too  much  divided  upon  the  whole 
circumference  of  the  iron,  to  affect  any  part  materially;  whereas,  a  few 
particles  of  steel  having  to  encounter  successively  many  of  iron,  the  heat, 
generated  by  the  attrition,  accumulates  in  the  former,  so  as  to  produce  visi- 
ble ignition. 

347.  This  case  differs  from  that  of  pure  collision,  since,  although  heat  is 
produced  in  the  abraded  particles,  it  is  also  produced  in  the  mass ;  and  it 
differs  from  that  of  friction,  since,  although  both  of  the  masses  are  heated, 
the  greatest  heat  is  evolved  in  the  matter  which  is  abraded. 

Heat  produced  by  Combination. 

348.  The  union  of  tin  or  lead  with  platinum  is  productive  of  a  remark- 
able elevation  of  temperature.     For  the  exhibition  of  this  phenomenon,  both 
metals  must  be  in  the  state  of  foil,  and  the  more  fusible  metal  rolled  up  in 
the  platinum,  so  as  to  form  a  scroll  as  large  as  can  be  conveniently  ignited 
by  means  of  the  blowpipe.     As  soon  as  the  scroll  reaches  a  reel  heat,  it  be- 
comes instantaneously  incandescent,  the  union  being  effected  with  an  as- 
tonishing energy. 


IMPONDERABLE  SUBSTANCES. 


Experimental  Illustration. 

349.  Tin  foil  and  platinum  foil  are  rolled  up  into  a 
scroll,  the  tin  being  innermost,  and  the  whole  subjected 
to  the  flame  of  the  hydro-oxygen  blowpipe,  supplied  by 
currents  of  hydrogen  gas  and  atmospheric  air.  Almost  as 
soon  as  the  mass  reddens,  it  becomes  incandescent  with 
an  energy  almost  explosive.  (250,  &c.) 

Boiling  Heat  produced  in  Alcohol,  by  the  Mixture  of  Sulphuric  Acid 

with  Water. 

350.  The  evolution  of  caloric,  produced  by 
the  mixture  of  liquids,  has  long  been  an  object 
of  attention  among  chemists.     A  sensible  in- 
crease of  temperature  arises  from  the  mixture 
and  consequent   combination   of  alcohol  with 
water.     When  sulphuric  acid  is  added  to  water, 
an  analogous  result  ensues,  but  the  rise  of  tem- 
perature is  much  greater.     The  heat,  thus  gene- 
rated, may  be  conveniently  exhibited  by  means 
of  the  apparatus  represented  by  the  adjoining 
figure,  and  the  process  which  I  am  about  to  de- 
scribe. 

351.  Into  the  inner  tube  introduce  as  much 
alcohol,  coloured  to  render  it  more  discernible, 
as  will  occupy  it  to  the  height  of  three  or  four 
inches.     Next  pour  water  into  the  outer  tube, 
till  it  reaches  about  one-third  as  high  as  the  li- 
quid contained  in  the  inner  tube ;  and  afterwards 
add  to  the  water  about  three  times  its  bulk  of 
concentrated  sulphuric  acid.     The  liquid  in  the 
inner  tube  will  soon  boil  violently,  so  as  to  rise 
in  a  foam. 

Solution  the  Means  of  producing  Heat  or  Cold. 

352.  Solution  produces  either  heat  or  cold,  according  to  the  nature  of  the 
substance  dissolved  and  of  the  solvent  employed. 

353.  In  absorbing  and  dissolving  gaseous  ammonia  or  chlorohydric  acid 
gas,  the  resulting  liquid  becomes  hot.     Water  becomes  cold  in  dissolving 
nitre,  and  still  colder  in  dissolving  nitrate  of  ammonia.     Sulphuric  acid  be- 
comes at  first  boiling  hot,  and  afterwards  freezing  cold,  by  successive  addi- 
tions of  snow. 

Evolution  of  Caloric  by  Mechanical  Action  inducing  Chemical  Decom- 
position. 

354.  With  the  view  of  showing  the  necessity  of  distinguishing  heat  as  a 
latent  cause  from  sensible  heat,  the  explosion  of  a  fulminating  powder  by 
percussion  was  exhibited.     This  phenomenon  falls  under  the  definition 
given  at  the  head  of  this  article.     Ignition  produced  in  this  way  has  of  late 
been  advantageously  applied  to  fire-arms  and  fowling  pieces.  (30.) 


CALORIC.  63 

355.  It  seems  probable  that  the  mechanical  force  of  the  blow  causes 
some  particles  of  the  compound  to  be  nearer  to  each  other;  in  consequence 
of  which  an  arrangement  of  the  elements  ensues,  inconsistent  with  the  re- 
tention of  the  large  quantity  of  caloric  with  which  they  were  previously 
combined. 

356.  The  inflammation  of  a  friction  match,  appears  to  me  to  arise  in  part 
from  heat  generated  by  friction,  and  in  part  from  mechanical  impulse,  in- 
ducing a  chemical  reaction  between  the  ingredients,  and  exposing  them  to 
the  air.    Matches,  which  take  fire  when  crushed,  owe  this  result  to  the  last 
mentioned  cause  only. 

357.  The  rationale  of  the  chemical  reaction  of  the  ingredients,  will  be 
given  under  the  heads  of  sulphur,  phosphorus,  and  the  chlorates. 

Heat  produced  by  Condensation  experimentally  illustrated. 

358.  Spunk  or  tinder  may  be  ignited,  if  introduced  into  a  condenser  of 
appropriate  construction,  and  the  air  forcibly  condensed  upon  it. 

359.  It  has  already  been  shown  that,  during  its  rarefaction,  air  becomes 
cooler,  while  during  its  condensation  it  becomes  warmer.     It  seems  that 
when  the  compression  is  carried  very  far,  so  much  caloric  is  liberated  as 
to  cause  ignition.  This  result  is  attained  by  means  of  a  small  condenser,  the 
construction  of  which  does  not  differ  from  that  which  has  been  described 
(145,  &c.),  excepting  that  a  cock  for  the  introduction  of  the  spunk  is  sub- 
stituted for  the  valves.     The  ignition  is  accomplished  by  having  the  piston 
so  situated,  as  that  there  may  be  as  much  air  as  possible  included  by  it, 
and  then  driving  it  home,  with  a  jerk,  so  as  to  condense  the  air  upon  the 
matter  to  be  ignited  with  great  force  and  rapidity.     Sometimes  the  instru- 
ment is  made  of  glass  without  a  cock,  so  that  the  ignition  may  be  seen;  the 
spunk  being  inserted  into  a  cavity  in  the  end  of  the  piston,  which  must  of 
course  be  withdrawn  as  soon  as  the  ignition  is  effected,  in  order  to  make 
any  useful  application  of  the  ignited  spunk. 

360.  It  appears  evidently  from  this  phenomenon  that,  in  air,  the  quantity 
of  caloric  in  proportion  to  the  ponderable  matter  lessens  as  the  density  in- 
creases.   Or,  in  other  words,  as  the  space  allotted  to  the  air  is  diminished. 

361.  This  inference  would  appear,  at  first  view,  irreconcilable  with  those 
experiments  which  demonstrate  that,  in  steam,  the  quantity  of  caloric  is 
always  directly  as  the  weight  of  water;  but  the  discordancy  disappears 
when  we  consider  that  the  heat  of  the  condensed  air  is  estimated  after  the 
escape  of  the  sensible  heat  liberated  by  the  compression;  while  in  the  case 
of  steam  this  cannot  be  permitted,  as  a  loss  of  sensible  heat  would  be  at- 
tended with  a  partial  condensation,  producing  a  proportionate  diminution  of 
density. 

362.  If  steam,  formed  at  the  boiling  point  of  212°,  and  having  no  access 
to  water  in  the  liquid  form,  were  to  be  raised  to  some  higher  temperature, 
500°  for  instance,  it  might  be  subjected  to  compression  without  being  par- 
tially liquefied ;  so  that  the  same  law  would  apply  to  it  as  to  atmospheric 
air,  which  always  exists  at  a  heat  far  above  its  boiling  point,  arid  has  no 
access  to  any  of  its  own  kind  of  ponderable  matter  in  the  liquid  form. 

363.  By  the  boiling  point  of  air,  I  mean  that  temperature  below  which 
it  would  become  liquid.    We  have,  I  think,  reason  to  infer  that  all  aeriform 
fluids  would  prove  susceptible  of  liquefaction,  if  our  ability  to  condense 
them,  or  our  power  of  producing  cold  were  unlimited. 


64  IMPONDERABLE  SUBSTANCES. 

364.  It  has  been  suggested  (257,  &c.),  that  the  caloric  thus  condensed 
may  belong  to  the  space,  and  not  to  the  air. 

Experimental  Illustration. 

365.  Spunk  ignited  in  consequence  of  the  compression 
of  air,  by  means  of  an  appropriate  condenser. 

Of  Fermentation  as  a  Source  of  Heat. 

366.  It  is  well  known  that  vegetable  substances,  while  undergoing  fer- 
mentation, acquire  a  great  accession  of  heat ;  and  that  green  hay  is  at 
times  spontaneously  ignited.    The  heat  generated  in  stable  litter  is  employed 
to  sustain  the  temperature  necessary  to  the  corrosion  of  the  metal  in  the 
manufacture  of  white  lead. 

Of  Vitality  as  a  Source  of  Heat. 

367.  The  temperature  of  warm  blooded  animals  demonstrates  the  power 
of  animal  life  to  evolve  caloric.    In  no  other  respect  is  chemical  reaction  so 
analogous  to  that  which  takes  place  within  the  domain  of  vitality,  as  in 
their  common  association  with  heat,  both  as  cause  and  effect.     The  old 
chemical  law  that  bodies  do  not  act  unless  fluid,  to  which  the  actual  excep- 
tions are  but  few,  shows  how  much  the  processes  of  chemistry  are  depen- 
dent on  the  principle,  without  which  there  could  be  no  fluidity.     The  de- 
pendency of  life  on  temperature  is  self-evident.     Seeds  and  eggs  lie  dor- 
mant until  excited  by  a  due  degree  of  heat. 

Of  the  Means  of  exciting  or  supporting  Heat  for  the  Purposes  of 
Chemistry. 

368.  It  is  well  known  that  the  activity  of  fire  is  dependent  on  the  supply 
of  air,  as  well  as  on  the  quantity  and  quality  of  the  fuel. 

369.  As  the  air  which  comes  into  contact  with  a  fire  is  necessarily  much 
rarefied  by  the  expansive  power  of  heat,  it  has  consequently  a  tendency 
to  ascend  in  a  vertical  current,  giving  place  to  the  colder  and  heavier  air 
in  the  vicinity,  agreeably  to  the  principles  already  illustrated.     See  (282) 
and  (286).    The  limits  of  this  vertical  current  of  heated  air,  in  the  case  of  a 
smoky  lamp  flame,  are  well  indicated  by  the  fuliginous  particles.     It  may, 
however,  be  observed  that  the  influx  of  the  cold  air  takes  place  not  only  on 
a  level  with  the  flame,  where  it  must  quicken  the  combustion,  but  also  above 
the  flame,  where  it  narrows  the  heated  column  and  retards  its  progress. 
In  the  Argand  lamp,  a  glass  chimney  defends  the  vertical  current  from 
lateral  pressure,  until  it  has  attained  a  sufficient  height  to  cause  an  adequate 
current  of  air  to  act  upon  the  flame. 

370.  In  conformity  with  the  principle  thus  illustrated  by  this  elegant  and 
useful  contrivance,  all  air  furnaces  are  constructed.     The  hot  air  and  va-. 
pour  proceeding  from  the  fire,  being  received  into  a  flue,  or  the  furnace 
being  tall  enough  of  itself  to  protect  the  ascending  current,  all  the  air  which 
flows  in  to  take  its  place  is  made  to  pass  through  the  fuel. 

371.  It  would  not  be  expedient  to  take  up  the  time  of  the  student  with  a 
detailed  explanation  of  the  various  furnaces  used  by  chemists.     Some  of 
them  will  be  introduced   in  subsequent  illustrations,  as  associated  with 


CALORIC.  65 

processes,  in  which  their  utility  and  the  method  of  using  them  will  be 
evident. 

Experimental  Illustration. 

372.  An  Argand  lamp  shown  and  explained.     Also  an 
Argand  lamp  with  concentric  wicks. 

Of  the  Bellows,  and  of  Forge  Fires.  ' 

373.  The  bellows  is  so  universally  known  as  the  means  of  exciting  com- 
bustion employed  by  smiths,  as  to  render  it  scarcely  necessary  to  mention 
the  forge  fire  as  among  the  most  efficient  and  convenient  methods  of  pro- 
ducing heat  for  the  purposes  of  chemistry.     The  supply  of  air  is,  in  this 
case,  yielded  by  an  operation  analogous  to  that  of  the  condenser.  (148,  &c.) 

374.  In  the  double  bellows,  the  additional  compartment  performs  a  part, 
in  equalizing  the  efflux,  equivalent  to  that  of  the  air  vessel  in  the  case  of 
the  forcing  pump,  the  valves  operating  in  the  same  way.  (143.) 

Lamp  without  Flame. 

375.  About  the  wick  of  a  spirit  lamp,  a  fine  wire  of 
platinum  is  coiled,  so  as  to  leave  a  spiral  interstice  be- 
tween the  spiral  formed  by  the  wire ;  a  few  turns  of  which 
should  rise  above  the  wick.  If  after  lighting  a  lamp  thus 
constructed,  the  flame  be  extinguished  by  a  gentle  blast, 
or  the  transient  application  of  an  extinguisher,  the  wire 
will  be  found  to  remain  red  hot ;  as  it  retains  sufficient 
heat  to  support  the  combustion  of  the  alcoholic  vapour, 
although  the  temperature  is  inadequate  to  produce  inflam- 
mation. 


376.  Rationale. — The  metallic  coil  appears  to  serve  as  a  reservoir  for 
the  caloric,  and  gives  to  the  combustion  a  stability,  of  which  it  would  other- 
wise be  deficient.  There  is  some  analogy  between  the  operation  of  the 
wire  in  acting  as  a  reservoir  of  heat  in  this  chemical  process,  and  that 
of  a  fly  wheel  as  a  reservoir  of  momentum  in  equalizing  the  motion  of 
machinery. 

Of  the  Mouth  Blowpipe. 


377.  As  a  fire  is  quickened  by  a  blast  from  a  bellows,  so  a  flame  may 
be  excited  by  a  stream  of  air  propelled  through  it  from  the  blowpipe.  The 
instrument  known  by  this  name,  is  here  represented  in  one  of  its  best  forms. 
It  is  susceptible  of  various  other  constructions ;  all  that  is  essential  being  a 
pipe  of  a  size  at  one  end  suitable  to  be  received  into  the  mouth,  and  to- 
wards the  other  end  having  a  bend  nearly  rectangular,  beyond  which  the 
bore  converges  to  a  perforation,  rather  too  small  for  the  admission  of  a 
9 


66 


IMPONDERABLE  SUBSTANCES. 


common  pin.     There  is  usually,  however,  an  enlargement,  as  represented 
in  this  figure,  to  collect  the  condensed  moisture  of  the  breath. 

378.  The  mouth  blowpipe  is  of  great  service  in  assaying  minute  por- 
tions of  matter,  so  as  to  form  a  general  idea  of  their  nature.     The  cele- 
brated Berzelius,  who  has  written  an  octavo  volume  on  the  subject  of  this  in- 
strument, informs  us  that  by  means  of  it  Gahn  discovered  tin  in  a  mineral, 
in  which  it  had  not  been  detected  by  analysis,  although  existing  only  in  the 
proportion  of  one  per  cent :  also  that  he  had  often  seen  him  extract  a  glo- 
bule of  metallic  copper  from  the  ashes  of  a  quarter  of  a  sheet  of  paper. 
The  utility  of  the  mouth  blowpipe  will  be  manifested  in  several  future  illus- 
trations. 

Of  the  Enameller 's  Lamp. 

379.  A  lamp,  so  made  as  to  be  excited  by  a  jet  of  air  from  a  stationary 
blowpipe,  supplied  by  a  double  bellows,  gasometer  or  gas-holder,  is  employ- 
ed much  by  chemists  and  artists  for  bending  glass  tubes,  or  heating  them  so 
as  to  blow,  on  them,  bulbs  for  thermometers.    Such  lamps  having  been  ori- 
ginally used  by  enamellers,  are  designated  accordingly. 

Of  the  Hydro-Oxygen  or  Compound  Blowpipe. 

380.  In  the  year  1801,  by  the  invention  of  the  hydro-oxygen  or  compound  blow- 
pipe, of  which  I  published  an  account  the  following  year,  I  was  enabled  to  fuse  se- 
veral of  the  pure  earths  which  had  previously  been  deemed  infusible ;  and  likewise 
not  only  to  fuse,  but  to  volatilize  pure  platinum.    Subsequently,  my  friend  Professor 
Sillirnan,  by  a  more  extended  use  of  the  instrument,  fused  a  great  number  of  sub- 
stances insusceptible  of  fusion  by  the  common  blowpipe.     My  memoir  was  repub- 
lished  in  London,  in  Tilloch's  Magazine;  also,at  Paris,  in  the  Annales  de  Chimie, 
and  was  noticed  by  Murray  in  his  treatise  of  chemistry,  and  by  Dr.  Hope,  in  his 
lectures;  yet,  when  a  modification  of  the  hydro-oxygen   blowpipe  was  contrived  by 
Mr.  Brooke,  Dr.  Clarke,  by  means  of  this  modification,  repeated  my  experiments 
and  those  of  Professor  Silliman,  without  any  other  notice  of  our  pretensions  than 
such  as  were  calculated  to  convey  erroneous  impressions. 

Engraving  and  Description  of  an  improved  Compound  Blowpipe  and  its  Appendages. 
8 


G 


381.  The  following  figure  represents  a  compound  blowpipe  which  I 
executed  myself  in  the  year  1813;  but,  fearing  it  might  be  deemed 


contrived  and 
unnecessarily 


CALORIC.  67 

complex,  I  did  not  then  publish  an  account  of  it.  Experience  has  shown  that  the 
complication  of  its  structure  does  not  render  it  more  difficult  to  use  than  the  sim- 
plest instruments  intended  for  the  same  purpose  ;  while  its  parts  are  peculiarly  sus- 
ceptible of  advantageous  adjustment. 

:>-2.  B  is  a  brass  ball,  with  a  vertical  perforation,  terminating  in  a  male  screw 
above,  and  in  a  female  screw  below.  Another  perforation,  at  rigfht  angles  to  this, 
causes  a  communication  with  the  tube  t,  which  enters  the  ball  at  right  angles.  A 
similar  but  smaller  brass  ball  may  be  observed  above,  with  perforations  similar  to 
those  in  the  larger  ball,  and  a  tube,  in  like  manner,  entering  it  laterally.  This  ball 
terminates  in  a  male  screw  below  as  well  as  above.  The  thread  of  the  lower  screw 
is  curved  to  the  left,  while  that  of  the  screw  of  the  larger  ball,  which  enters  the 
same  nut,  n,  is  curved  to  the  right.  Hence  the  same  motion  causes  the  male  screws 
to  approach,  or  recede  from  each  other,  and  thus  determines  the  degree  of  compres- 
sion given  to  a  cork  which  is  placed  between  them  in  the  nut.  At  S,  above  the  ball, 
a  small  screw  may  be  observed,  with  a  milled  head.  This  is  connected  with  a  small 
tube  which  passes  through  the  cork  in  the  nut,  n,  and  reaches  nearly  to  the  external 
orifice,  o,  from  which  the  flame  is  represented  as  proceeding.  This  tube  is  for  the 
most  part  of  brass,  but  at  its  lower  end  terminates  in  a  tube  of  platinum.  It  com- 
municates by  lateral  apertures  with  the  cavity  of  the  upper  ball,  but  is  prevented  by 
the  cork  from  communicating  with  the  cavity  in  the  other  ball.  Hence  it  receives 
any  gas  which  may  be  delivered  into  the  upper  ball  from  the  lateral  pipe  which  en- 
ters that  ball,  but  receives  none  of  the  gas  which  may  enter  the  lower  ball,  B. 

383.  Into  the  female  screw  of  the  latter,  a  perforated  cylinder  of  brass,  r.,  with  a 
corresponding  male  screw,  is  fitted.     The  perforation  in  this  cylinder  forms  a  conti- 
nuation of  that  in  the  ball,  but  narrows  below,  and  ends  in  a  small  hollow  cylinder 
of  platinum,  which  forms  the  external  orifice  of  the  blowpipe,  o. 

384.  The  screws,  s  sss,  are  to  keep,  in  the  axis  of  the  larger  ball,  the  tube  which 
passes  through  it  from  the  cavity  of  the  smaller  ball.     The  intermediate  nut,  by 
compressing  about  the  tube  the  cork  which  surrounds  it,  prevents  any  communica- 
tion between  the  cavities  in  the  two  balls.     By  the  screw,  S,  in  the  vertex,  the  ori- 
fice of  the  central  tube  may  be  adjusted  to  a  proper  distance  from  the  external  ori- 
fice.    Three  different  cylinders,  and  as  many  central  tubes  with  platinum  orifices  of 
different  calibres,  were  provided,  so  that  the  flame  might  be  varied  in  size,  agreeably 
to  the  object  in  view. 

385.  I  have  always  deemed  it  best  to  transmit  the  oxygen  gas  through  the  tube  in 
the  axis,  since  two  volumes  of  the  hydrogen  being  required  for  one  volume  of  oxy- 
gen, the  larger  tube  ought  to  be  used  for  the  former;  and  the  jet  of  hydrogen  is 
placed  between  a  jet  of  oxygen  within  it,  and  the  atmospheric  air  without. 

386.  Under  the  table  is  a  gallows,  G,  with  a  screw  for  attaching  a  pipe,  leading 
from  a  self-regulating  reservoir  of  hydrogen. 

387.  In  order  to  put  this  apparatus  into  operation,  it  is  affixed  to  a  table,  as  repre- 
sented in  the  figure,  or  to  a  smaller  stand,  and   secured  to  the  side  of  the  hydro- 
pneumatic  cistern,  so  as  to  be  conveniently  situated  for  receiving  the  oxygen  from  a 
gas-holder,  through  the  pipe,  P,  and  the  hydrogen  through  a  pipe  attached  at  G. 

388.  Another  pipe,  proceeding  from  a  reservoir  of  hydrogen  gas,  is  attached,  by 
means  of  the  screw  and  gallows,  G,  to  one  of  the  tubes  communicating  with  the 
blowpipe. 

389.  The  cavity  of  the  hydrostatic  blowpipe  may  be  supplied,  either  with  oxygen, 
or  atmospheric  air.     In  either  case,  in  order  to  have  the  instrument  in  full  operation, 
it  is  only  necessary  to  open  the  cocks  duly,  and  inflame  the  hvdrogen. 

390.  The  heat  produced,  in  this  way,  by  the  combustion  of  hydrogen  with  atmos- 
pheric air,  is  sufficient  to  fuse  platinum;  and  when  oxygen  gas  is  employed,  that 
metal,  or  any  other,  may  be  volatilized.     The  facility  with  which  the  hydro-oxygen 
flame,  whether  excited  by  pure  oxygen  or  common  air  merely,  may  be  made  to  act, 
in  any  convenient  direction,  renders  it  peculiarly  serviceable  in  many  operations;  its 
superior  cleanliness  is  a  great  recommendation. 

Of  Drummond's  Lime  Light,  and  of  DanielVs  and  Maugham's  Blowpipe,  so  called 

crroncovshj. 

391.  Much  has  been  said  in  some  of  the  British  newspapers,  of  the  application  in 
light-houses,  of  the  light  reflected  by  lime,  when  subjected  to  the  flame  of  the  com- 
pound blowpipe.     This  is  treated  as  a  new  invention,  although  in  my  original  Me- 
moir, published  in  the  year  1802,  I  spoke  of  the  light  so  created  as  intolerable  to  the 
naked  eye.     A  similar  observation  will  be  found  in  the  description  given  by  my 
friend,   Professor  Silliman,   of  the  phenomenon   in  question.     It  follows   that  the 
English  operator  can  only  lay  claim  to  a  new  application  of  a  previous  discovery. 


68  IMPONDERABLE  SUBSTANCES. 

392.  In  my  original  memoir  on  the  hydro-oxygen  blowpipe,  I  described  and  repre- 
sented by  engravings  two  methods  of  causing  the  currents  of  the  two  gases  employed, 
to  meet.  Agreeably  to  one  of  these,  two  perforations  were  made  to  unite  and  form  one, 
at  about  the  tenth  of  an  inch  from  the  external  orifice,  so  as  that  a  section  of  the  ag- 
gregate would  resemble  in  shape  the  letters  XY.     Agreeably  to  the  other  method,  a 
smaller  tube  was  made  to  enter  and  to  be  concentric  with  a  larger  one,  the  latter 
being  a  little  longer,  so  as  that  at  a  little  distance  from  its  end,  the  orifice  of  the 
former  terminated.     The  oxygen  being  supplied  through  the  inner  tube,  and  the  hy- 
drogen through  the  outer  one,  the  admixture  of  the  oxygen  with  the  hydrogen,  took 
place  within  the  bore  of  the  external  tube,  at  a  small  distance  from  its  orifice. 

393.  Not  being  enabled  to  procure  any  platina  at  the  time,  I  could  not  construct  a 
blowpipe,  of  the  last  mentioned  kind,  sufficiently  refractory ;  but  about  the  year 
1815, 1  constructed  the  compound  blowpipe  above  described,  and  exhibited  it  to  Pro- 
fessor Silliman,  who  mentioned  this  fact  in  a  letter  written  within  a  year  afterwards. 
From  the  time  that  I  was  elected  Professor  of  Chemistry  in  1818,  I  have  employed 
this  form  of  the  instrument,  of  which  an  engraving  and  description  was  given  in  the 
Franklin  Journal  (Vol.  I,  1826,  p.  195,)  of  a  simpler  instrument  upon  the  same  prin- 
ciple, an  engraving  and  description  of  which  will  be  found  in  Silliman's  Journal  for 
1822.    Yet  both  Professor  Daniell  and  Mr.  Maugham,  resorted  to  analogous  con- 
trivances.    The  former  has  been  called  Daniell's  hydro-oxygen  blowpipe,  the  other 
also  is  distinguished  by  the  name  of  its  contriver.     It  differs  from  mine  essentially, 
only  in  being  recurved  into  an  acute  angle,  so  as  to  throw  the  flame  on  a  cylinder  of 
lime,  for  the  purpose  of  illumination.     In  order  to  accomplish  the  same  object,  1  had 
only  to  direct  mine  obliquely  upwards,  instead  of  resorting  to  a  direction  deviating  a 
little  from  the  perpendicular,  as  is  usually  preferable.     It  is  surprising  that  under 
these  circumstances,  Maugham  should  have  received  a  premium  for  the  instrument 
which  he  had  thus  modified,  without  any  reference  to  the  original  inventor. 

Improved  Process  for  the  Fusion  of  Platinum. 

394.  Latterly  by  multiplying  the  jets,  and  using  great  pressure,  I  have  been  ena- 
bled to  fuse  more  than  two  pounds  troy,  of  platinum,  into  a  malleable  mass.     The 
method  which  I  employed,  was  the  same  essentially  as  that  described  in  Silliman's 
Journal,  as  abovementioned.     The  gases  are  made  to  mingle  in  a  common  cavity, 
and  afterwards  to  supply  jet  tubes  of  about  the  usual  size  of  those  employed  for 
blowpipes;  these  are  to  be  made  more  or  less  numerous,  in  proportion  to  the  quantity 
of  metal  to  be  fused.    The  great  desideratum  is  to  have  the  pressure  on  the  gases, 
sufficiently  great,  and  at  the  same  time  perfectly  steady. 

MEANS  OF  PRODUCING  COLD,  OR  RENDERING  CALORIC  LATENT. 

Cold  by  Vaporization. 

395.  The  cold  produced  by  evaporation  has  been  illus- 
trated by  an  experiment  in  which  a  jet  of  ether,  co-operat- 
ing with  a  blast,  was  productive  of  the  congelation  of  wa- 
ter.    Pure  prussic  acid  will  enable  me  hereafter  to  exhibit 
a  phenomenon  still  more  surprising;  I  mean  that  of  the 
freezing  of  one  portion  of  a  liquid,  by  the  vaporization  of 
another  portion.     I  shall  now  proceed  to  show  that  the 
freezing  of  water  may  be  caused  by  the  ebullition  of  ether. 

Water  Frozen  by  Boiling  Ether. 

396.  Let  a  portion  of  water,  just  adequate  to  cover  the  bottom,  be  in- 
troduced into  the  vessel   represented  in  the  following  engraving,  as  sus- 
pended within  a  receiver.     Over  the  water  let  ether  be  added,  in   quan- 
tity sufficient  to  form  a  stratum  from  an  eighth  to  a  quarter  of  an  inch 
in  depth.     If,  under  these  circumstances,  the  receiver  be  placed  on  the  air- 
pump  plate,  and  sufficiently  exhausted,  the  water  freezes,  while  the  ether 
boils. 


CALORIC.  69 

397.  Rationale. — The  freezing  of  the  water  in 
contact  with  the  boiling  ether,  is  in  consequence  of 
that  increased  capacity  to  combine  with  caloric 
already  explained.  (186.)  Under  these  circum- 
stances, the  boiling  point  of  the  other  is  de- 
pressed below  the  freezing  point  of  water;  and 
consequently  it  causes  the  congelation  of  that  li- 
quid from  the  same  cause,  that  melted  tin  or  lead 
will  congeal  under  boiling  water. 


Engraving  and  Description  of  an  Apparatus  and 
Process  for  the  rapid  Congelation  of  Water, 
by  the  explosive  Evolution  of  Ethereal  Vapour 
consequent  to  the  combined  influence  of  Rare- 
faction, and  the  absorbing  power  of  Sulphuric 
Acid.* 


398.  The  retort  A,  contains  a  small  portion  of  water  covered  by  a 
stratum  of  hydric  sulphuric  ether.  The  vessel  B,  holds  a  stratum  of  sul- 
phuric acid  of  about  two  inches  deep,  at  the  deepest  part.  Into  a  tubulure 
in  the  side  of  this  vessel,  the  beak  of  the  retort  is  ground  to  fit  air-tight,  and 

*  By  the  liberality  of  the  American  Philosophical  Society,  I  am  permitted  to  intro- 
duce this  article  in  my  Compendium,  although  communicated  to  them  for  a  volume 
of  their  Transactions  now  in  the  press. 


70 


IMPONDERABLE  SUBSTANCES. 


is  made  to  receive  one  end  of  a  recurved  tube,  of  which  the  other  end  de- 
scends about  half  an  inch  below  the  surface  of  the  acid.  There  is  a  mer- 
cury bottle,  C,  of  which  the  mouth  is  well  closed,  and  which  is  furnished  with 
two  cocks,  one  of  which  communicates  with  the  air  pump,  the  other  with 
the  vessel,  B.  The  mode  of  operating  is  as  follows:  the  bottle  is  previously 
exhausted,  and  kept  in  a  state  of  exhaustion  by  closing  both  of  the  cocks, 
the  pump  being  put  into  operation  and  the  cocks  opened  simultaneously,  the 
power  of  the  acid  to  absorb  the  vapour,  co-operating  with  that  of  the  va- 
cuum and  the  pump  in  exhausting  the  air  and  vapour  from  the  retort,  causes 
an  explosive  vaporization  of  the  ether,  and  a  consequent  rapid  congelation 
of  the  water. 

Congelation  of  Water  in  an  exhausted  Receiver  by  the  aid  of  Sulphuric 

Acid. 

399.  In  the  experiment  above  illustrated,  water  is  frozen  by  the  rapid 
abstraction  of  caloric,  consequent  to  the  copious  vaporization  of  ether  when 
unrestrained  by  atmospheric  pressure.  In  vacuo,  water  undergoes  a  vapo- 
rization, analogous  to  that  of  the  ether  in  the  preceding  experiment;  but  the 
aqueous  vapour  evolved  in  this  case  is  so  rare,  that  it  cannot  act  against 
the  air-pump  valves  with  sufficient  force,  to  allow  of  its  being  pumped  out  of 
a  receiver  with  the  rapidity  requisite  to  produce  congelation.  However,  by 

the  process  which  I  am  about 
to  describe,  water  may  be 
frozen  by  its  own  vaporization. 
400.  A  thin  dish,  or  pane 
of  glass,  covered  by  a  small 
quantity  of  water,  and  situated 
over  some  concentrated  sul- 
phuric acid  in  a  broad  vessel, 
is  placed  within  a  receiver, 
on  the  air-pump  plate,  as  re- 
presented in  the  annexed  en- 
graving. Under  these  circum- 
stances, the  exhaustion  of  the 
receiver  causes  the  congelation 
of  the  water. 

401.  Rationale. — So  long  as  there  is  no  diminution  of  the  thin  aqueous 
vapour  which,  in  the  absence  of  the  air,  occupies  the  cavity  of  the  receiver, 
the  elastic  reaction  of  that  vapour  prevents  the  production  of  more  vapour; 
but  when,  as  in  the  case  in  point,  the  vapour  is  largely  in  contact  with  sul- 
phuric acid  and  consequently  rapidly  absorbed,  a  corresponding  vaporiza- 
tion of  the  water  takes  place  to  supply  the  deficiency  thus  created.     The 
caloric  requisite  for  the  generation  of  the  vapour  thus  formed,  is  taken  from 
the  residual  liquid,  which  finally  freezes  in  consequence.  (229.) 

Improved  Apparatus  for  freezing  Water  by  the  aid  of  Sulphuric  Acid. 

402.  Finding  the  experiment,  for  which  the  apparatus  represented  by  the 
preceding  figure  is  usually  employed,  liable  to  fail  from  the  imperfection  of 
cocks,  dependent  for  their  efficacy  on  a  metallic  joint,  I  contrived  the  appa- 
ratus which  the  opposite  engraving  is  intended  to  represent,  and  which  I 
shall  proceed  to  describe.     A  brass  cover  is  so  well  fitted  to  the  rim  of  a 


Apparatus  for  the  Congelation  of  Water  in  Vacuo,  by  means  of 
Sulphuric  Acid. 


(Page  70.) 


CALORIC.  71 

large  glass  jar  as  to  be  quite  air-tight.  In  operating,  the  bottom  of  the  jar 
was  covered  with  sulphuric  acid,  and  another  jar  with  feet,  also  supplied 
with  acid  enough  to  make  a  stratum  half  an  inch  deep  on  the  bottom,  is  in- 
troduced as  represented.  The  bottom  of  the  vessel  last  mentioned,  is,  by 
means  of  the  feet,  kept  at  such  a  height  above  the  surface  of  the  acid  in  the 
outer  jar,  as  not  to  touch  it.  Upon  the  surface  of  the  glass  vessel,  a  small 
plate  of  very  thin  sheet  brass  is  placed,  made  concave  in  the  middle,  so  as 
to  hold  a  small  quantity  of  water.  The  brass  cover  is  furnished  with  three 
valve  cocks,  one  communicating  with  the  air-pump,  another  with  a  barome- 
ter gauge,  and  the  third  with  a  funnel  supplied  with  water. 

403.  With  the  apparatus  thus  arranged,  having  made  a  vacuum  on  a 
Saturday,  I  was  enabled  to  freeze  water  situated  on  the  plate,  and  to  keep 
up  the  congelation  till  the  Thursday  following.     As  water  in  the  state  of 
ice  evaporates  probably  as  fast  as  when  liquid,  the  whole  quantity  frozen 
would  have  entirely  disappeared  during  the  night,  but  for  the  assistance  of 
a  watchman  whom  I  engaged  to  supply  water  at  intervals.    At  a  maximum 
I  suppose  the  mass  of  ice  was  at  times  about  two  inches  square,  and  from 
a  quarter  to  a  half  an  inch  thick.     The  gradual  introduction  of  the  water, 
by  aid  of  the  funnel  and  valve  cock,  and  of  the  pipe  represented  in  the 
figure,  by  which  it  was  conducted  to  the  cavity  in  the  sheet  brass,  enabled 
me  to  accumulate  a  much  larger  mass  than  I  could  have  otherwise  pro- 
cured.    The  brass  band  which  embraces  the  inner  jar  near  the  brim,  with 
the  three  straps  proceeding  from  it,  serves  to  keep  this  jar  in  a  proper  posi- 
tion ;  that  is,  concentric  with  the  outer  jar. 

404.  In  this  experiment,  I  employed  an  air-pump  upon  a  new  construc- 
tion, which  I  contrived  a  few  years  ago,  and  of  which  a  description  will  be 
given  in  the  Appendix. 

405.  Congelation,  as  effected  in  the  experiments  above  described,  may  be 
accomplished  by  the  aid  of  any  substance  having  a  very  strong  affinity  for 
water,  as  for  instance  chloride  of  calcium,  clay,  or  whinstone,  after  having 
been  rendered  anhydrous  by  ignition.     Even  parched  meal  or  flour  has 
been  successfully  employed  in  the  process. 

Of  the  Freezing  of  Mercury  by  the  Vaporization  of  Ice. 

406.  If  a  pear-shaped  mass  of  ice  containing  the  metal  be  suspended 
over  a  large  surface  of  sulphuric  acid,  and  a  good  exhaustion  obtained,  it 
will  freeze  the  quicksilver  which  may  be  kept  solid  for  several  hours. 

Wollastori's  Cryophorus. 

407.  The  adjoining  figure  represents  the  cryophorus,  or 
frost  bearer,  an  instrument  invented  by  the  celebrated  Wollas- 
ton,  in  which  congelation  is  produced  in  one  cavity  by  rapid 
condensation  in  another,  consequent  to  refrigeration. 

408.  In  form,  this   instrument  obviously  differs  but  little 
from  the  palm  glass,  already  described.  (213,  &c.)  It  is  supplied 
by  the  same  process  with  a  small  portion  of  water  instead  of 
alcohol;  so  that  there  is  nothing  included  in  it  but  water, 
either  liquid  or  in  vapour. 

409.  The  cryophorus  being  thus  made,  if  all  the  water  be 
i       allowed  to  run  into  the  bulb  near  the  bent  part  of  the  tube, 

C   J    and  the  other  bulb  be  immersed  in  a  freezing  mixture,  the 
^—       water  will  be  frozen  in  a  few  minutes. 


72  IMPONDERABLE  SUBSTANCES. 

410.  Rationale. — There  is  no  difference  between  the  causes  of  this  phe- 
nomenon and  those  by  which  the  congelation  of  water  in  vacuo  is  effected 
by  the  aid  of  sulphuric  acid;  excepting  that  in  the  one  case  the  aqueous 
vapour  is  absorbed  by  the  acid,  in  the  other  condensed  by  the  cold.  In 
either  instance  it  is  rapidly  removed,  and  a  proportionably  rapid  vaporiza- 
tion of  the  water  ensues,  abstracting  the  caloric  of  fluidity  from  the  residual 
portion. 


Large  Cryophorus. 


o 


411.  This  figure  represents  a  very  large  cryophorus,  the  blowing  of 
which  I  superintended,  and  by  means  of  which  I  have  successfully  repeated 
Wollaston's  experiment. 

412.  This  instrument  was  about  four  feet  long,  with  bulbs  of  about  five 
inches  in  diameter. 

Modification  of  the  Cryophorus. 

413.  Two  flasks,  of  which  the  necks  have  flanged  orifices,  are  so  secured 
in  a  wooden  frame  that,  by  the  pressure  of  screws,  S  S,  and  gum  elastic 
disks,  the  orifices  of  a  tube  are  made  to  form  with  them  severally,  air-tight 
junctures.     The  orifices  of  the  tube  are  furnished  with  brass  flanges,  which 
correspond  with  those  terminating  the  necks  of  the  flasks. 


414.  Midway  between  the  junctures  a  female  screw  is  soldered  to  the 
tube  for  the  insertion  of  a  valve  cock  V,  by  means  of  which,  and  a  flexible 
tube  extending  to  an  air-pump,  the  flasks  may  be  exhausted,  and  then 
closed.     A  small  quantity  of  water  having  been  previously  introduced  into 
one  of  them,  if,  while  the  exhaustion  is  sustained,  the  other  flask  be  refrige- 
rated by  ice  and  salt,  the  water  will  be  frozen. 

415.  This  apparatus  may  be  applied  to  the  purpose  of  desiccation,  by 
placing  the  article  to  be  dried  in  one  receptacle,  and  quicklime,  chloride  of 
calcium,  or  concentrated  sulphuric  acid  in  the  other.     The  orifice  of  the 
receptacles  may  be  made  larger  without  inconvenience.     Two  large  cylin- 
ders, for  instance,  may  be  used. 


CALORIC.  73 

Chemical  Combination  as  a  Cause  of  Cold. 

416.  Chemical  union,  although  more  frequently  the  cause  of  increased 
temperature,  is  in  many  cases  productive  of  the  opposite  effect. 

417.  There  are  few  instances  of  chemical  union,  which  are  not  accom- 
panied by  a  change  of  capacity.     Of  the  cause  of  such  changes,  we  are 
utterly  ignorant,  and  of  course  have  no  more  reason  to  wonder  when,  by  an 
absorption  of  caloric,  cold  is  the  consequence  of  chemical  reaction,  than 
when,  by  an  evolution  of  caloric,  heat  arises  from  the  same  source. 

418.  In  the  case  of  the  solution  of  snow  in  concentrated  sulphuric  acid, 
already  adduced,  we  find  these  opposite  effects  resulting  apparently  from  the 
same  cause.    Under  the  same  head  of  solution,  as  a  cause  of  heat  or  cold,  it 
was  mentioned  that  nitre  and  nitrate  of  ammonia  produce  cold  during  their  so- 
lution.   This  is  equally  true  in  the  case  of  many  other  salts.     But  the  most 
efficient  mean  of  artificial  cold,  is  the  solution  of  ice,  in  consequence  of  the 
reaction  between  it  and  the  more  deliquescent  salts,  or  the  mineral  acids. 

419.  It  may  be  inferred,  from  the  statements  already  made,  that  the 
temperature  of  freezing  water,  or  melting  ice,  is  32° ;  and  that  when  ice  is 
surrounded  by  other  bodies  at  a  higher  temperature,  it  will  continue  to  ab- 
stract from  them  the  caloric  necessary  to  its  fusion,  until  it  be  all  liquefied. 
It  must  be  evident  that  the  minimum  temperature  which  can  be  thus  attain- 
ed is  32°.     But  by  mingling  ice  in  a  divided  state,  with  certain  salts  or 
acids,  having  a  great  affinity  for  water,  and  which  form  with  it  compounds 
of  which  the  freezing  point  is  lower  than  32°,  the  mass  will  abstract  caloric 
from  adjoining  bodies  in  a  mode  quite  analogous  to  that  in  which  ice  has 
been  stated  to  operate;  while  the  minimum  temperature  attainable  is  as 
much  lower  as  the  freezing  point  is  lower.     Thus  the  freezing  point  of  salt 
and  snow  is  about  zero  of  Fahrenheit's  scale;  consequently  on  mingling 
salt  with  snow,  the  liquefaction  of  the  resulting  mass  will  proceed,  at  any 
temperature  above  zero,  to  abstract  caloric  from  all  adjoining  bodies  until 
they  are  as  cold  as  the  mixture.     By  the  addition  of  crystallized  chloride 
of  calcium,  or  of  diluted  nitric  or  sulphuric  acid,  to  snow,  a  compound  may 
be  formed,  of  which  the  freezing  point  is  below  that  at  which  mercury 
freezes,  or — 39°.     Housekeepers  have  latterly  availed  themselves  of  the 
influence  of  salt,  to  remove  ice  from  the  marble  steps  at  the  entrance  of 
their  dwellings;  as  in  this  way  it  may  it  may  be  detached  without  injury  to 
the  marble. 

Table  of  Freezing  Mixtures. 

420.  The  following  tables  are  taken  from  Thomson's  Outline  of  the 
•Sciences  of  Heat  and  Electricity,  page  191. 

Frigorific  Mixtures  without  Ice. 

Degree  of 
Mixtures.  Tlr-nnometcr  sinks,  rold    pro- 

Parts.  ilucod. 

Nitrate  of  ammonia  -         -         -     1  )      ,-,  .    rnri  . 

Water 1  \      From  +  50    to  +  4°  4b 

Nitrate  of  ammonia        -         -         -         -     1  i  * 

Carbonate  of  soda          -         -         -         -     1 V      From  +  50°  to  —  7°.  57 

Water  ...  .  ;1;J 

Phosphate  of  soda          -         -         -         -     9  >      n 

Diluted  nitric  acid         -         -         -         I    4$      From  +  °°°  ^  -  ^  C2 

Phosphate  of  soda          -         -         -         -     9} 

Nitrate  of  ammonia       -         -        -        -    6V      From  -f-  50°  to  —  21°.  71 

Diluted  nitric  acid         -         -         -         -     4  S 

Sulphate  of  soda  .... 

Muriatic  acid 

Sulphate  of  soda  .... 

Diluted  sulphuric  acid 

10 


From  +  50°  to  0°.  50 

From  +  50°  to  -f-  3°.  47 


74 


IMPONDERABLE  SUBSTANCES. 


Mixtures. 


Snow,  or  pounded  ice 
Muriate  of  soda 
Snow,  or  pounded  ice 
Muriate  of  soda 
Nitrate  of  ammonia 

Part 

:    '-    :]} 

":    ":    :1| 

Q  > 

Diluted  sulphuric  acid 
Snow 
Muriatic  acid 

-        -        -    2j 

-    8) 
-    5$ 
7  ? 

Diluted  nitric  acid 

-    4 
.     4 

Muriate  of  lime     - 
Snow 
Cryst.  muriate  of  lime 

-    5 
-    2 
.    3 

Cryst.  muriate  of  lime 
Snow 
Cryst.  muriate  of  lime 

-        -        -    2 
-     1 
-    3 

-     8 

Diluted  sulphuric  acid 

-  10 

Degree  of 
cold  pro- 
duced. 


55 

59 
62 
72 
82 
6G 
33 
23 


Frigorific  Mixtures  with  Ice. 

Thermometer  sinks, 
Parts. 
t)  \ 
71  >      From  any  temp,  to  —  5°. 

From  any  temp,  to  —  25°. 

From  +  32°  to  —  23°. 
From  +  32°  to  —  27°. 
From  -f-  32°  to  —  30°. 
From  +  32°  to  —  40°. 
From  -f  32°  to  —  50°- 
From  0°  to  —  66°. 
From  —  40°  to  73°. 
From  —  68°  to  —  91°. 

STATES  IN  WHICH  CALORIC  EXISTS  IN  NATURE. 

421.  With  two  of  the  modes  in  which  caloric  exists  in  nature,  the  stu- 
dent of  this  Compendium  has  been  made  acquainted ;  and  these  are  the  only 
modes  of  its  existence  generally  recognised.     As  it  exists  in  one  of  them,  it 
is  called  sensible  heat,  being  susceptible  of  detection  by  the  senses,  or  by  the 
thermometer.     In  the  other  it  is  called  latent  heat,  because  the  quantity  pre- 
sent in  that  mode  of  existence,  is  not  open  to  those  means  of  detection.     But 
even  in  this  latent  state,  caloric  is  known  to  be  influenced  by  temperature; 
being  liable  to  be  removed  entirely  from  vapours,  or  liquids,  by  communi- 
cation with  colder  substances;  so  as  to  render  its  subsequent  presence  in 
these,  a  proof  of  its  previous  existence  in  the  matter  from  which  it  may 
have  been  abstracted. 

422.  It  seems  to  me,  however,  that,  in  some  substances,  caloric  evidently 
exists  in  a  state  in  which  it  is  wholly  independent  of  external  changes  of 
temperature.      In  this  predicament  I  suppose  it  to  reside  in  the  nitrates, 
chlorates,  and  fulminates,  and  generally  in  all  detonating  compounds. 

423.  If,  agreeably  to  the  received  chemical  doctrines,  we  are  to  ascribe 
the  explosive  power  of  such  compounds  to  combined  caloric,  it  must  be  evi- 
dent that  its  condensation  in  them  is  wonderfully  great.     Yet  no  good  reason 
can  be  assigned  for  this  prodigious  condensation.     It  cannot  be  ascribed 
simply  to  the  attraction  of  ponderable  matter ;  since  the  same  ponderable 
matter  which  confines  it  at  one  moment,  liberates  it  in  the  next  without  any 
adequate  assignable  cause. 

424.  Thus  the  presence  of  platinum  sponge,  a  cold  metallic  congeries, 
causes  the  caloric  of  a  gaseous  mixture  of  hydrogen  and  oxygen  to  escape 
explosively.     An  electric  spark,  or  the  contact  of  any  ignited  matter,  pro- 
duces the  same  result.     The  case  of  gunpowder,  exploded  by  the  ignition 
of  the  most  minute  portion  of  the  mass,  is  equally  unaccountable,  and  like- 
wise the  explosive  recomposition  of  water  by  a  discharge  from  the  same 
galvanic  wires,  by  which  its  decomposition  may  have  been  effected. 

425.  The  almost  irresistible  extrication  of  oxygen  in  the  gaseous  state 


LIGHT.  75 

from  oxygenated  water,  by  contact  with  the  oxide  of  silver,  is  still  more  in 
point  and  even  more  surprising. 

426.  I  conceive,  therefore,  that  in  detonating  compounds,  caloric  is  held 
in  a  peculiar  state,  dependent  on  some  hidden  cause,  of  which  the  de- 
tection would  probably  unfold  many  mysteries  in  galvanism  and  electro- 
magnetism,  as  well  as  in  chemistry.  I  deem  it  more  than  probable  that 
the  cause  of  electricity  is  the  principal  agent  in  these  mysterious  phenomena. 


—•*•••*— 

SECTION  II. 

,   LIGHT. 

427.  It  must  necessarily  belong  to  chemistry  to  treat  of 
light,  so  far  as  it  is  productive  of  heat,  deoxydizement,  and 
other  chemical  effects,  and  so  far  as  it  is  evolved  by  chemi- 
cal processes. 

428.  According  to  Newton,  light  is  a  subtile  fluid,  which 
is  either  radiated  or  reflected  from  every  visible  point  in 
the  universe,  in  consequence  of  its  elasticity  or  the  self- 
repellant  power  of  its  particles. 

429.  It  comes  from  the  sun,  about  ninety-five  millions 
of  miles,  in  eight  minutes,  or  nearly  at  the  rate  of  two 
hundred  thousand  miles  in  a  second. 

430.  Light  appears  to  have  no  sensible  weight.     The 
products  of  the  combustion  of  phosphorus,  carbon,  and 
other  combustibles,  appear  fully  equal  in  weight  to   the 
ponderable  matter  employed.     It  follows  that  the  loss  of 
the  light  and  heat  occasions  no  diminution  of  weight;  yet 
enough  is  emitted  by  the  flame  of  a  candle  or  lamp  to  be 
perceived  by  many  hundred  millions  of  eyes.     There  is  not 
a  luminous  point  in  the  universe,  from  which  a  sphere  of 
rays  is  not  emitted,  in  radius  equal  to  any  distance  from 
which  that  point  may  be  seen. 

431.  According  to  Huygens,  Euler,  Young,  Fresud,  and  others,  light  is 
due  to  the  undulations  of  a  rare  elastic  medium,  or  ether,  which  pervades 
the  universe.     This  opinion  has,  within  the  last  forty  years,  gained  the  ap- 
probation of  a  majority  of  men  of  science.     The  doctrine  of  Newton  is, 
however,  less  difficult  to  comprehend,  and  serves  sufficiently  to  associate  the 
phenomena  intelligibly.  Besides,  so  long  as  we  assume  the  existence  of  a  ma- 
terial cause  of  calorific  repulsion,  (11,  &c.)  we  cannot  consistently  explain 
the  quick  communication  of  heat  (289,  &c.)  without  supposing  that  the  parti- 
cles of  caloric  radiate  from  hot  bodies,  as  do  those  of  light  from  luminous 
bodies,  agreeably  to  the  Newtonian  doctrine.     But  if  calorific  radiation  be 
ascribed  to  the  emission  of  material  particles  by  hot  bodies,  it  would  be  in- 


76 


IMPONDERABLE  SUBSTANCES. 


consistent  not  to  ascribe  the  analogous  phenomena  of  light  to  a  like  cause. 
In  obedience  to  these  considerations  I  shall  resort  to  this  theory  in  treating 
of  light  as  a  chemical  agent,  not  without  a  hope  that  the  objections  which 
have  been  made  to  it,  may  hereafter  find  an  answer  in  some  new  view  of  the 
subject. 

Of  the  Sources  of  Light. 

432.  As  a  source  of  light,  the  sun  is  obviously  even 
more  prolific  than  as  a  source  of  heat;  and  it  must  be 
evident,  that  all  the  processes  which  produce  ignition  must 
also  produce  light. 

433.  There  are  some  cases  in  which  light  is  emitted 
without  heat.     As  it  comes  to  us  from  the  moon,  as  emit- 
ted by  luminous  insects,  decayed  wood,  or  the  phosphores- 
cent wave,  it  appears  to  be  unaccompanied  by  caloric. 

434.  In  the  fire-fly,  and  in  many  other  insects,  it  is 
evolved  by  vital  action. 


Refraction  of  Light. 


M 


435.  When  a  ray  of  light  passes  obliquely  from  a  rarer  into  a  denser  medium,  it  is 
bent  towards  the  perpendicular  direction.     When  the  course  of  the  oblique  ray  is 
from  the  denser  medium  into  one  which  is  rarer,  it  is  bent  from  the  perpendicular 
direction. 

436.  Suppose  F  G  X  Z  to  be  a  body  of  water.     If  a  pencil  of  the  solar  rays  fall 
upon  the  surface  of  the  water  perpendicularly  at  C,  it  will  penetrate  the  water  with- 
out deviating  from  its  previous  course  ;  for  whatever  may  be  the  attraction  between 
the  light  and  the  water,  it  cannot  cause  any  deflection,  since  it  must  act  equally  on 
either  side  of  each  ray.     But  should  a  pencil  of  rays  passing  through  the  tube,  B, 
and  penetrating  the  water  at  C,  reach  the  bottom,  it  would  shine  on  the  pebble,  D; 
whereas,  it  would  shine  upon  Z,  were  the  water  removed.     The  light  in  this  case 
passing  from  a  rarer  into  a  denser  medium,  and  entering  the  latter  obliquely,  the  rays 
are  attracted  by  the  denser  medium  most  on  the  side  nearest  to  it,  and  consequently 
are  bent,  or  refracted,  from  their  previous  course. 


LIGHT.  77 

437.  About  C,  as  a  centre,  describe  the  circle,  F  H  E,  and  from  A  draw  a  diameter, 
ACE,  perpendicular  to  the  surface  of  the  water.     Let  the  lines  B  C,  C  I,  repre- 
sent the  path  of  the   light  in  passing  from  the   tube  to  the  bottom  of  the  water. 
Where  these  lines  intersect  the  circle,  draw  K  H,  I  L,  parallel  to  the  surface  of  the 
water.     The  angle  A  C  H,  which   the   incident  ray  makes  with  the  perpendicular, 
is  called  the  angle  of  incidence,  and  K  H  the  sine  of  this  angle.     I  C  E  is  called 
the  angle  of  refraction,  and  I  L  its  sine.     In  the  case  of  water,  the  sine   I  L  is  al- 
ways found  to  be  the  sine  K  H,  as  3  to  4;  but  were  a  mass  of  glass  substituted  for 
the  water,  the  sine  of  the  angle  of  refraction  to  that  of  incidence  would  be  as  2  to  3, 
and  if  the  glass  were  replaced  by  a  similar  mass  of  diamond,  the  ratio  would  be 
nearly  as  2  to  5  :  the  ratio  being  always  invariable  in  the  same  medium,  whatever 
the  angle  of  incidence  may  be  ;  for  if  the  pencil  of  rays  were  to  proceed  to  C,  from 
a  tube  at  M,  making  the  angle  of  incidence,  ACM,  and  the  angle  of  refraction, 
Y  C  E,  the  sine,  Y  Q,  would  be  the  sine,  R  O,  in  the  same  ratio  as  I  L  to  K  H  ;  and 
this  would  hold  good  as  before  stated,  whether  F  G  X  Z  were  water,  diamond,  crys- 
tal, or  any  other  homogeneous  and  transparent  refracting  medium.     The  refraction, 
which  has  been  thus  described  as  taking  place  daring  the  passage  of  rays  from  air 
into  other  denser  media,  equally  ensues  when  light  passes  out  of  such  media  into  the 
air.  Nor  is  it  in  air  alone  that  it  takes  place  ;  it  is  enough  that  the  substances  through 
which  it  passes  be  of  different  densities,  or  chemically  different  in  their  natures. 
Combustible  liquids  or  solids  have  been  found  to  refract  most  powerfully.   It  was  his 
discovery  of  this  association  between  combustibility  and  refracting  power,  that  led 
Sir  Isaac  Newton  truly  to  infer  the  combustible  nature  of  the  diamond,  from  its  su- 
perior efficacy  in  causing  refraction. 

438.  As  an  illustration  of  the  case  of  light  refracted,  in  passing  out  of  denser 
matter  into  rarer,  let  us  imagine  the  eye  of  an  observer  placed  at  the  upper  orifice  of 
the  tube,  B,  in  the  figure.  Instead  of  the  pebble,  Z,  which  he  would  see  if  the  water 
were  removed,  the  pebble,  B,  will  be  seen  by  him.     Hence  the  well  known  power 
of  water  in  rendering  an  object  visible,  when,  in  the  absence  of  the  liquid,  our  view 
would  be  intercepted  by  the  side  of  the  containing  vessel;  and  hence  likewise  the 
broken  image  which  a  stick  or  cord  presents  to  us,  when  seen  partially  under  water. 

Difference  between  the  Refracting  Influence  of  a  Triangular  Prism,  and  of  a  Plate  or 

Pane  of  Glass. 

439.  In  passing  through  a  plate  of  glass  whose  surfaces  are  parallel,  the  refraction 
which  light  sustains  from  one  surface,  is  compensated  by  an  opposite  refraction  by 
the  other  surface  ;  but  during  its  passage  through  a  prism  as  represented  in  the  fol- 
lowing diagram,  it  is  subjected  to  a  concurrent  refraction  from  two  surfaces. 

440.  Supposing  that  the  re- 
fracting  medium,  F  G  X  Z,  in 
the  last  figure,  were  bounded 
by  air  below  as  well  as  above, 
and  its  upper  and  lower  sur- 
faces  were  parallel,  as  in  the 
case  of  a  plate  or  pane  of  glass, 
a  ray  of  light  in  passing  ob- 
liquely through  it,  would  be 
equally  attracted,  on  one  side,  as 
it  enters,  on  the  other  side  as  it 


emerges.  Hence,  after  its  emer- 
gence, it  will  proceed  parallel 


*D 


on  a  prism,  as  represented  in  the  foregoing  figure,  in  the  direction  of  the  line,  A  B; 
agreeably  to  the  preceding  demonstration,  it  will,  on  account  of  the  obliquity  of  its 
approach,  be  refracted  towards  C,  and  emerging  from  C,  obliquely  to  another  sur- 
face of  the  prism,  H  C  K,  it  will  be  again  most  attracted  by  that  portion  of  the  sur- 
face towards  which  it  inclines.  Consequently,  it  will  be  refracted  so  as  to  proceed 
in  the  direction  C  D. 

442.  Thus  it  must  be  evident  that  the  two  surfaces  of  the  prism  have  a  concurrent 
influence  in  bending  the  rays  from  their  previous  course;  while  in  the  pane,  the  in- 
fluence of  one  surface  is  compensated  by  that  of  the  other. 

443.  The  lines,  L  F  and  E  F,  being  perpendiculars  to  the  surfaces  of  the  prism, 
A  B  L  is  the  angle  of  incidence,  and  F  B  C,  the  angle  of  refraction,  to  the  surface 
at  which  the  rays  enter  the  prism.    F  C  B  is  the  angle  of  incidence,  and  E  C  D,  the 
angle  of  refraction  to  the  surface  from  which  the  rays  emerge. 


78 


IMPONDERABLE  SUBSTANCES. 


Dispersion  of  Light. 


444.  Besides,  the  refraction  sustained  by  a  pencil  of  rays,  agreeably  to  the  pre- 
ceding illustration,  they  undergo  another  alteration,  the  effects  of  which  are  very 
pleasing,  and,  agreeably  to  the  doctrine  of  Newton,  highly  instructive,  being  the 
foundation  of  his  theory  of  colours. 

445.  Light  appears  to  consist  of  particles  of  different  kinds;  each  kind  having  the 
property  of  producing  on  the  retina  of  the  eye  a  peculiar  impression,  which  being 
conveyed  to  the  sensoriura  creates  the  idea  of  a  colour.     The  rays  thus  capable 
of  acting  differently  on  the  retina,  seem  to  be  unequally  susceptible  of  refraction. 
Hence,  in  passing  through  the  prism,  they  are  separated  from  each  other,  forming  a 
beautiful  series  of  all  the  various  colours  of  the  rainbow,  in  an  oblong  figure  called 
the  spectrum.    Under  these  circumstances,  the  rays  are  said  to  be  dispersed,  and  the 
process  by  which  they  are  separated  is  called  dispersion. 


446.  Let  A  B  represent  a  part  of  a  window  shutter  of  a  room,  into  which  light 
enters  only  through  the  hole  C.  If  the  light  thus  entering  be  received  on  a  screen, 
a  circular  spot  on  it  will  be  made  luminous.  But  if  a  glass  prism,  D  O  E,  be  placed 
before  the  hole,  so  that  the  light  may  fall  advantageously  upon  the  prism,  the  rays, 
which  had  before  produced  the  luminous  circle,  will  be  refracted  and  dispersed,  so 
as  to  form  the  spectrum,  r  g  v,  consisting  of  the  following  colours,  arranged  in  the 
following  order — red,  orange,  yellow,  green,  blue,  indigo,  violet. 

Of  the  Heating,  Illuminating,  and  Chemical  Properties  of 

the  Rays. 

447.  The  red  rays  are  found  to  be  pre-eminent  in  heat- 
ing power;  the  violet  as  remarkable  for  their  superior 
influence  in  certain  chemical  changes,  dependent  on  deoxi- 
dation.     In  the  middle  of  the  spectrum,  the  rays  have  the 
highest  power  of  illumination. 

448.  Besides  the  rays  thus  mentioned,  there  are  invisi- 
ble, heat-producing  rays  beyond  the  red,  and  invisible  rays 
producing  deoxidation  beyond  the  violet. 

449.  Agreeably  to   the  observations   of  Herschel,  to 
whom  we  are  indebted  for  the  discovery  of  these  invisible 
rays,  the  greatest  heating  and  deoxidizing  power  exists 
just  beyond  the  limits  of  the  visible  spectrum;  but  from 


LIGHT.  79 

' 

experiments  made  by  Seebe'ck  and  Mellone,  it  appears  that 
the  location  of  the  principal  heating  power  is  dependent 
on  the  nature  of  the  refracting  medium. 

450.  In  the  spectrum  produced  by  crown  or  plate  glass, 
the  principal  heat  was  in  the  red,  and  in  that  procured  by 
flint  glass,  beyond  the  red;  a  variety  of  transparent  liquid 
media  having  been  made  to  occupy  the  cavities  of  several 
hollow  glass  prisms,  it  was  found  that  when  a  prism  was- 
occupied  by  water  or  alcohol,  the  maximum  of  heat  was  in 
the  yellow  rays;  when  it  was  filled  with  sulphuric  acid,  or 
solutions  of  sal-ammoniac  or  corrosive  sublimate,  the  max- 
imum heat  was  in  the  orange. 

451.  Of  the  rays  perceptible  by  the  eye,  the  red,  being 
the  least  bent  from  their  previous  course,  are  obviously 
the  least  refrangible;  and  it  is  no  less  obvious  that  the 
violet,  being  the  most  bent,  are  the  most  refrangible;  also 
that  those  rays,  which  are  found  equidistant  from  the  red, 
and  violet,  have  a  mean  refrangibility. 

452.  An  opinion  has  been  entertained  by  some  philoso- 
phers that  there  are  only  three  original  and  distinct  species 
of  light,  which  seems  lately  to  be  sanctioned  by  one  of  the 
most  celebrated  opticians  of  modern  times.     I  allude  to 
Sir  David  Brewster,  whose  opinions  I  shall  give,  by  quot- 
ing them  in  his  own  language,  from  his  Treatise  upon 
Optics,  page  68,  American  edition. 

453.  "  With  the  view  of  obtaining  a  complete  analysis  of  the  spectrum,  I  have 
examined  the  spectra  produced  by  various  bodies,  and  the  changes  which  they  un- 
dergo by  absorption  when  viewed  through  various  coloured  media,  and  I  find  that 
the  colour  of  every  part  of  the  spectrum  may  be  changed  not  only  in  intensity,  but 
in  colour,  by  the  action  of  particular  media;  and  from  these  observations,  which  it 
would  be  out  of  place  here  to  detail,  I  conclude  that  the  solar  spectrum  consists  of 
three  spectra  of  equal  lengths,  viz.  a  red  spectrum,  a  yellow  spectrum,  and  a  blue 
spectrum.     The  primary  red  spectrum  has  its  maximum  of  intensity  about  the  mid- 
dle of  the  red  space  in  the  solar  spectrum,  the  primary  yellow  spectrum  has  its  max- 
imum in  the  middle  of  the  yellow  space,  and  the  primary  blue  spectrum  has  its  max- 
imum between  the  blue  and  the  indigo  space.     The  two  minima  of  each  of  the  three 
primary  spectra  coincide  at  the  two  extremities  of  the  solar  spectrum. 

454.  "From  this  view  of  the  constitution  of  the  solar  spectrum  we  may  draw  the 
following  conclusions: — 

455.  "  1.  Red,  yellow,  and  blue  light  exist  at  every  point  of  the  solar  spectrum. 

456.  "  2.  As  a  certain  portion  of  red,  yellow,  and  blue  constitute  white  light,  the  co- 
lour of  every  point  of  the  spectrum  may  be  considered  as  consisting  of  the  predomi- 
nating colour  at  any  point  mixed  with  white  light.     In  the  red  space  there  is  more 
red  than  is  necessary  to  make  white  light  with  the  small  portions  of  yellow  and  blue 
which  exist  there ;  in  the  yellow  space  there  is  more  yellow  than  is  necessary  to 
make  white  light  with  the  red  and  blue  ;  and  in  the  part  of  the  blue  space  which  ap- 
pears violet  there  is  more  red  than  yellow,  and  hence  the  excess  of  red  forms  a  violet 
with  the  blue. 

457.  "  3.  By  absorbing  the  excess  of  any  colour  at  any  point  of  the  spectrum  above 
what  is  necessary  to  form  white  light,  we  may  actually  cause  white  light  to  appear 
at  that  point,  and  this  white  light  will  possess  the  remarkable  property  of  remaining 
white  after  any  number  of  refractions,  and  of  being  decomposable  only  by  absorption. 


80  IMPONDERABLE  SUBSTANCES. 

Such  a  white  light  I  have  succeeded  in  developing  in  different  parts  of  the  spectrum. 
These  views  harmonize  in  a  remarkable  manner  with  the  hypothesis  of  three  colours, 
which  has  been  adopted  by  many  philosophers,  and  which  others  had  rejected  from 
its  incompatibility  with  the  phenomena  of  the  spectrum." 

Triangular  Glass  Prism,  conveniently  mounted  on  a  universal  Joint. 

This  figure  represents  a  triangular 
glass  prism,  mounted  on  a  universal 
joint,  supported  by  a  brass  stand,  so 
as  to  be  well  qualified  for  the  disper- 
sion of  light,  agreeably  to  the  experi- 
ments alluded  to  in  the  preceding  ar- 
ticles. 

A,  the   glass   prism,  supported   at 
each  end  by  a  pivot. 

B,  B,  handles  by  means  of  which 
the  pivots  are  turned,  so  as  to  make 
the  prism  revolve. 

C,  C,  ball  and  socket,  forming  a 
joint,  upon  which  the  plate  D,  D,  may 

be  moved  so  as  to  assume  any  serviceable  position. 

Of  certain  Chemical  Effects  of  Light. 

458.  I  have  already  adverted  to  the  calorific  influence  of 
light,  and  to  its  power  of  producing  chemical  changes. 
Among  these,  the  bleaching  power  of  the  solar  rays  is  fa- 
miliar to  every  body.     In  this  process  the  rays  appear  to 
exercise  that  modifying  influence  on  the  attraction  of  pon- 
derable matter  already  alluded  to.  (20,21.)    Consequently 
a  new  arrangement  of  particles  ensues  in  lieu  of  that  which 
formed  the  colouring  matter.     Certain  vegetable  leaves,  if 
exposed  to  the  sun  in  water,  have  been  found  to  yield  oxy- 
gen gas.     Some  metallic  salts,  especially  nitrate  of  silver, 
are  blackened  by  exposure  to  light,  owing,  as  is  alleged,  to 
deoxydizemerit.  v  A  mixture  of  hydrogen  and  chlorine  will,  in 
the  dark,  remain  for  a  long  time  without  combining;  but 
in  the  rays  of  the  sun  will  explode.     According  to  Berze- 
lius,  the  power  of  producing  this  result  exists  only  in  the 
violet  rays. 

459.  Other  important  processes  in  which  chemical  reac- 
tion is  produced  by  the  agency  of  light,  will  be  mentioned 
as  I  proceed. 

Polarization  of  Light. 

460.  This  name  has  been  given  to  a  property  of  light, 
which  causes  it  often  to  be  divided  into  two  portions,  one 


LIGHT.  81 

of  which  is  transmitted,  the  other  reflected,  by  the  same 
pane  of  glass:  or  one  portion  sustains  refraction  in  an  or- 
dinary degree,  the  other  in  an  extraordinary  degree.  Again, 
all  these  properties  are  found  to  be  commutable,  so  that 
the  portion  of  the  rays  which  is  reflected  in  one  case,  may 
be  transmitted  in  another ;  or  that  which  in  one  case  sus- 
tains the  ordinary  refraction,  in  another  may  undergo  the 
extraordinary  refraction,  and  vice  versa. 

461.  These  phenomena  are  ascribed  to  the  different 
positions  assumed  by  the  different  groups  of  rays,  in  con- 
sequence of  which  certain  poles,  which  the  lumeniferous 
particles  are  supposed  to  possess,  are  variously  directed  at 
different  times,  so  as  to  determine  their  reflection,  or  trans- 
mission, or  the  degree  of  their  refraction. 

462.  In  consequence  of  this  diversity  of  position,  in  the 
poles  of  light-producing  particles,  and  the  peculiar  arrange- 
ment of  the  particles  of  certain  transparent  bodies,  those 
portions  of  light,  of  which  the  poles  are  favourably  situated 
for  transmission,  may  pass  through   such  bodies,  when 
other  portions,  of  which  the  polar  positions  are  different, 
may  be  reflected;  one  group  of  the  rays  may  undergo 
the  ordinary,  the  other  the  extraordinary  refraction.     Yet 
after  transmission,  reflection,  or  refraction,  the  polarity  of 
the   groups   of  rays  being   reversed,   those  which  were 
transmitted,  or  unusually  refracted,  in  the  first  instance, 
may,  in  the  second,  be  reflected,  or  only  ordinarily  refract- 
ed; while  such  as  were  reflected  at  first,  or  ordinarily 
refracted,  may,  in  the  second,  pass  through,  or  be  unusually 
refracted. 

463.  Latterly,  it   has   been   ascertained   by  Professor 
Forbes  of  Edinburgh,  that  the  non-luminous  rays  emitted 
by  heated  bodies,  are  susceptible  of  affections  analogous 
to  those  ascribed  to  the  polarization  of  light.     As  the 
phenomena  in  question  are  due  to  the  reaction  which  takes 
place  between  masses  and  particles,  agreeably  to  the  defi- 
nition at  the  commencement  of  this  work,  they  belong  to 
natural  philosophy  proper,  not  to  chemistry.    Yet  a  chemist 
cannot  be  indifferent  to  inquiries  which  tend  to  sanction,  or 
correct,  his  theoretic  deductions  respecting  the  important 
and  interesting  phenomena  of  heat. 

11 


OF  PONDERABLE  MATTER. 


464.  Whatever  may  be  the  real  state  of  the  case,  it  has  been  found  con- 
venient by  chemists,  during  the  last  forty  years,  to  assume  the  existence  of 
three  imponderable  principles,  in  order  to  account  for  certain  phenomena, 
and  associate  them  advantageously.     The  reasoning  which  tends  to  justify 
this  course,  has  been  already  briefly  stated.  (10  to  22.)     Of  two  of  those 
principles,  caloric  and  light,  I  have  treated  in  the  preceding  pages.     Of 
the  other  imponderable  principle,  electricity,  whether  statical  or  dynamic, 
separate  treatises  will  be  supplied. 

465.  In  the  next  place,  I  shall  treat  of  that  "kind  of  matter  which  is 
endowed  with  weight,  and  which  is  in  consequence  recognised  as  material 
by  the  mass  of  mankind."  (18.)     This  kind  of  matter  may  be  generically 
designated  as  ponderable. 

466.  In  treating  of  ponderable  matter,  it  has  been  deemed  expedient  to 
designate  substances,  which  are  exclusively  or  generally  the  products  of 
animal  and  vegetable  organization,  as  organic,  all  other  matter  being  desig- 
nated as  inorganic.     Hence,  nominally,  two  branches  of  chemistry  have 
been  created,  called  organic,  or  inorganic,  accordingly  as  the  objects  of  at- 
tention have  been  such  as  to  justify  the  one,  or  the  other  designation.     Yet 
it  is  undeniable  that  no  accurate  line  of  demarcation  can  be  drawn  between 
the  branches  thus  distinguished.     Substances  produced  by  animal  or  vege- 
table life,  may  in  several  instances  be  obtained  by  the  reaction  of  inorganic 
bodies;  the  phenomena  in  each  branch  are  dependent  on  the  same  ultimate 
elements;  and  in  almost  all  cases,  those  of  organic  chemistry  are  displayed 
by  means  of  agents  derived  from  the  inorganic  world. 

467.  Nevertheless,  the  separation  of  chemical  science  into  the  two  branches 
in  question,  seems  to  me  highly  advantageous  in  practice.     Few  persons 
who  are  not  chemists  by  profession,  can  acquire  more  than  a  general  chemi- 
cal knowledge  of  important  facts,  properties,  elements,  principles,  and  com- 
binations, with  so  much  theory  as  may  be  necessary  to  associate  them. 
With  those  details  and  minutiae,  of  which  organic  chemistry  mostly  consists, 
it  were  useless  to  endeavour  to  impart  a  knowledge  during  the  time  allotted 
to  an  education,  in  which  the  attention  of  the  learner  is  divided  between  seve- 
ral branches  of  science.     But  the  acquisition  of  that  degree  of  knowledge 
which  it  is  reasonable  to  expect  in  organic  chemistry,  is  quite  easy  to  a  stu- 
dent who  is  familiar  with  the  inorganic  department  of  this  science;  while 
to  one  ignorant  of  the  latter,  the  smallest  progress  in  the  former  is  utterly 
impracticable. 

468.  This  subject  will  be  recurred  to  when  I  enter  upon  organic  chemis- 
try.    Meanwhile,  after  treating  of  certain  general  properties  of  ponderable 
matter,  or  the  means  of  ascertaining  or  observing  them,  I  shall  proceed 
with  the  chemistry  of  inorganic  substances. 


CHEMICAL  ATTRACTION.  83 

OF  CERTAIN  GENERAL  PROPERTIES  OF 
PONDERABLE  MATTER, 

AND  OF  THE  MEANS  OF  ASCERTAINING,    OR  OBSERVING 

THEM. 

469.  As  introductory  to  the  consideration  of  the  indivi- 
dual inorganic  substances,  it  will  be  expedient  to  treat  of 
Chemical  Attraction,  Definite  Proportions,  Specific  Gravity, 
and  the  Mode  of  collecting  and  preserving  Gases,  formerly 
designated  as  Pneumatic  Chemistry.     These  subjects  will 
be  considered  in  the  four  following  sections. 

SECTION  I. 

OF  CHEMICAL  ATTRACTION. 

470.  The  word  chemical  has  been  used  to  designate  the, 
attraction  which  takes  place  between  heterogeneous  parti- 
cles only.     I  object  to  this  restriction  of  its  meaning,  be- 
cause I  consider  it  as  affording  a  natural  line  of  separation 
between  chemical  and  mechanical  philosophy,  to  consider 
the  one  as  treating  of  the  reaction  of  masses,  or  of  masses 
and  particles,  the  other  of  the  reaction  of  particles  only. 
Besides,  the  process  of  crystallization,  of  which  I  shaU  in 
the  next  place  treat,  arises  from  the  reaction  of  homoge- 
neous atoms;*  and  it  was  among  chemists  that  the  investi- 
gation or  observation  of  the  laws  and  phenomena  of  crys- 
tallization originated.     I  consider  the  force  which  causes 
homogeneous  atoms  to  cohere,  whether  in  the  crystalline 
form  or  otherwise,  as  a  species  of  chemical  attraction. 

471.  The  attraction  which  takes  place  between  homoge- 
neous particles,  is  designated  as  attraction  of  aggregation, 
attraction  of  cohesion,  or  homogeneous  attraction.     The  at- 
traction which  arises  between  heterogeneous  particles,  is 
called  chemical  affinity,  or  heterogeneous  attraction. 

Of  Attraction  of  Aggregation  or  Cohesion,  or  Homogeneous 

Attraction. 

472.  Of  this  kind  is  the  force  which  enables  bodies  to  re- 
sist mechanical  division.     Overcoming  it  does  not  alter  the 

*  I  use  the  word  particle  only  to  designate  those  elementary  portions  of  matter 
which  cannot  by  any  natural  means  be  divided.  Chemists  use  the  word  atom  to 
signify  either  such  a  particle,  or  the  smallest  portion  of  a  chemical  compound, 
which  can  exist  without  decomposition.  (472,  507,  550,  551.) 


84  PONDERABLE  MATTER. 

chemical  nature  of  a  substance.     It  is  the  cause  of  crystal- 
lization.    (See  note.) 

Of  Crystallization* 

473.  Almost  all  matter,  in  passing  from  the  fluid  to  the 
solid  state,  assumes  regular  forms  called  crystals.     As  it  is 
inconceivable  that  homogeneous  particles,  or  atoms,  can 
differ  in  size  or  shape,   it  is  not  wonderful   that  when 
united  by  the  same  attractive  force,  they  should  produce 
regular  forms.     To  produce  irregular  forms,  the  atoms,  or 
the  forces  actuating  them,  should  be  irregular.     In  fact,  as 
the  deposition  of  matter  from  solution,  or  on  the  evapora- 
tion of  the  solvent,  is  accelerated  or  retarded,  a  corres- 
ponding change  ensues  in  the  crystalline  form.     In  this 
way  various  deviations  arise  from  that  primary  form  which 
is  assumed  under  circumstances  which  allow  the  deposition 
to  proceed  at  the  same  rate  precisely.   Those  forms,  which 
deviate  from  the  primary  form,  are  called  secondary.    The 
various  steps  by  which  they  are  generated  from  the  pri- 
mary forms,  have  been  most  ingeniously  traced,  or  inferred, 
by  Hauy  and  others.     In  some  instances,  the  primary  or 
primitive  form  has  been  developed  by  cleavage. 

474.  It  was  at  one  time  the  general  impression,  that 
every  chemical  compound  had  an  appropriate  crystalline 
form.     Latterly  it  has  been  shown  that  certain  substances 
quite  different  in  their  nature,  as  for  instance,  phosphoric 
and  arsenic  acid,  assume  the  same  forms  in  crystallizing. 
Such  substances  are  said  to  be  isomorphous.     In  the  intro- 
duction to  Thomson's  Inorganic  Chemistry,  several  groups 
of  isomorphous  substances  are  mentioned. 

475.  Other  things  being  equal,  crystals  are  larger  in 
proportion  as  their  growth  is  slower.     They  shoot  from 
extraneous  bodies,  as  the  sides  of  the  receptacle,  or  from 
strings  or  sticks,  in  preference  to  crystallizing  in  an  isola- 
ted manner.     Agitation  hastens  their  production  but  con- 
fuses them.     The  crystalline  texture  of  some  of  the  trap 
rocks  is  attributed  to  slow  cooling.     The  same  matter 
fused,  and  allowed  less  time  to  cool,  forms  a  glass. 

*  The  details  of  crystallography,  as  they  have  been  presented  by  Hatly  and  others, 
are  of  themselves  so  copious  as  to  require  for  their  remembrance  a  greater  effort  of 
the  mind  than  all  the  chemistry  which  I  expect  a  candidate  for  a  medical  degree  to 
acquire.  It  is  evidently  one  of  those  subjects  of  which  a  copious  knowledge  cannot 
be  imparted  advantageously  during  a  strictly  medical  education.  The  instruction 
which  I  shall  endeavour  to  give  upon  this  topic,  will  be  extremely  brief. 


CHEMICAL  ATTRACTION. 


85 


476.  Berzelius  alleges  that,  if  two  flasks,  both  containing 
a  saturated  solution  of  two  parts  of  nitrate  of  potash  and 
one  of  sulphate  of  soda,  be  surrounded  with  ice  or  cold 
water,  on  introducing  a  crystal  of  nitrate  of  potash  into 
one  and   a  crystal  of  sulphate  of  soda  into  the  other, 
crystals  will  be  formed  in  each  flask,  of  the  same  nature 
as  that  of  the  crystal  introduced.     Nitrate  of  potash  will 
be  found   crystallized  exclusively  in  the  flask  first  men- 
tioned, and  sulphate  of  soda  as  exclusively  in  the  other. 

477.  Crystals  are  found  in  nature  and  are  produced  ar- 
tificially. 

478.  The  precious  stones  are  native  crystals.     Carbo- 
nate of  lime,  common  salt,  and  gypsum,  are  native  pro- 
ducts, often  crystalline  in  form. 

Of  the  Goniometer,  or  Jingle  Measure;  an  Instrument  for  measuring  the  Jingles  of 

Crystals. 

479.  Crystals  may  appear  to  be  exactly  similar  to  the  eye;  but  when  compared  by 
means  of  accurate  instruments  called  goniometers,  they  will  often  be  found  to  differ 
in  their  angles.     Of  these  instruments  there  are  two  constructions  ;  one,  being  more 
easy  to  be  used,  is  of  more  general  utility ;  the  other,  contrived  by  Wollaston,  is 
complicated,  but  when  skilfully  employed  is  capable  of  giving  more  accurate  re- 
sults. 

480.  The  instrument  of  the  easiest  application,  and  which  is  usually  employed,  is 
represented  by  the  following  engraving. 

Of  the  Common  Goniometer. 


451.  Its  construction  is  founded  upon  the  15th  proposition  of  Euclid,  which  de- 
monstrates that  the  opposite  angles,  made  by  any  two  lines  in  crossing  each  other 
are  equal.  Hence  it  follows  that  the  angles  made  by  the  legs,  B  B,  B  C  B,  of  this 
instrument,  above  and  below  the  pivot  on  which  they  revolve,  are  equal  to  each 
other.  Consequently,  if  they  be  made  to  close  upon  any  solid  crystalline  angle,  pre- 
sented to  them  at  C,  they  will  comprise  a  similar  angle  on  the  other  side  of  the' cen- 
tre about  which  they  turn.  This  angle  is  evidently  equivalent  to  that  of  the  crystal 


86  PONDERABLE  MATTER. 

and  is  ascertained  by  inspecting  the  semicircle,  A,  graduated  into  180  degrees,  pre- 
cisely in  the  same  manner  as  a  protractor. 

482.  The  construction  of  goniometers  is  usually  such  as  to  allow  the  legs  to  be 
detached  from  the  arch,  in  order  to  facilitate  their  application  to  crystalline  angles ; 
and  yet,  so  that  they  may  be  reapplied  to  the  semicircle,  without  deranging  them 
from  the  angle  to  which  they  may  have  been  adjusted. 

483.  The  piece  of  brass,  in  which  the  pivot  is  fastened,  slides  in  a  slit  in  each  leg; 
so  as  to  permit  them  to  be  made  of  a  suitable  length,  on  the  side  on  which  the  crys- 
tal is  applied. 

Of  Wollastoris  Goniometer. 

484.  The  process  by  which  angles  are  ascertained  by  means  of  Wollaston's  gonio- 
meter is  as  follows: — 

485.  The  crystal  to  be  examined  is  attached  to  an  axis,  and  so  adjusted,  by  means 
of  suitable  mechanism,  that  the  image  of  a  window  bar  may  be  seen  reflected  from 
one  of  the  crystalline  faces,  so  as  to  coincide  with  a  line   (seen  directly)   drawn  on 
the  wall  under  the  window,  parallel  to  the  window  bar.     By  a  partial  revolution  of 
the  axis,  and  consequently  of  the  crystal,  a  similar  coincidence  of  the  images  of  the 
bar  and  line  is  produced  by  means  of  another  face  of  the  crystal,  being  the  next  to 
that  first  employed-. 

486.  Meanwhile  the  number  of  degrees  of  a  circle  moved  through,  in  changing 
the  crystal  from  the  first  to  the  second  position,  is  measured  by  an  index  on  a  gradu- 
ated arch,  and  the  degrees  of  the  angle,  which  the  surfaces  make  with  each  other, 
thus  ascertained. 

Various  Modes  of  causing  Artificial  Crystallization. 

487.  Fusion  followed  by  congelation. — Instances:  Crystal- 
lized sulphur,  bismuth,  antimony,  zinc. 

488.  Solution  followed  by  evaporation  in  open  vessels. — 
Exemplified  by  salts,  acids,  alkalies,  sugar. 

489.  Solution  with  heat  followed  by  refrigeration. — Most  of 
the   substances   which  crystallize   by   evaporation,  yield 
crystals  in  this  way. 

490.  Solution  followed  by  vaporization  at  the  boiling  heat. — 
Crystals  may  be  thus  obtained  from  many  salts,  but  are 
always  minute. 

491.  Solution  followed  by  saturation. — Instances:  Potash 
saturated  by  carbonic  acid  or  chlorine. 

492.  Sublimation. — This  comprises  the  idea  of  vaporiza- 
tion, and  condensation  into  a  state  of  solidity.     Instances: 
Corrosive  sublimate,  calomel,  iodine,  arsenic. 

493.  Solution  followed  by  precipitation;  as  in  the  case  of 
the  arbor  Dianse  and  arbor  Saturni. 

Crystalline  Specimens  exhibited. 

494.  A  wooden  arch,  about  fifteen  inches  high  and  a  foot 
wide,  encrusted  with  fine  blue  crystals  of  the  sulphate  of 
copper:  also  baskets  constructed  of  bonnet- wire,  curiously 
studded  with  elegant  crystals  of  the  same  salt.     Crystals 
of  the  ferroprussiate  of  potash,  more  properly  called  cy- 
anoferite  of  potassium,  suspended  by  a  cord  on  which  the 


CHEMICAL  ATTRACTION.  87 

crystals   were  deposited  during   their   formation.    (475.) 
These  crystals  are  of  an  agreeable  lemon-yellow  colour. 

495.  A  crystalline  congeries  of  alum,  about  a  hundred 
pounds  in  weight.    Baskets  studded  with  crystals  of  the 
same  salt. 

496.  Large  cluster  of  crystallized  borax. 

497.  Crystals  of  corrosive  sublimate  and  calomel. 

498.  Crystals  of  sulphur,  arsenic,  bismuth,  antimony,  &c. 

499.  Various  other  crystalline  bodies. 

Of  Decry  stallization. 

50Q.  It  has  been  ascertained  by  Dr.  Daniell  that  crystals 
may  be  partially  developed  by  solution.  When  alum  is 
slowly  dissolved,  its  crystalline  structure  becomes  very 
evident. 

501.  Specimen  of  decry stallized  alum. 

Of  Water  of  Crystallization. 

502.  The  well  known  spiculae,  which,  by  their  appearance 
on  the  surface  of  water,  indicate  incipient  freezing,  are 
crystals.     In  fact,  it  was  from  the  Greek  name  for  ice, 
*gi/erT«AAfl«,  that  the  word  crystal  was  adopted ;  as  crystals 
were  correctly  considered  as  the  products  of  a  process 
analogous  to  freezing.     This  is  strictly  true  in  the  case  of 
crystals  resulting  from  the  congelation  of  matter  from  a 
state  of  fusion.     Water  enters  into  the  constitution  of 
many  crystals  which,  when  robbed  of  it  by  heat  or  desic- 
cation, lose  the  crystalline  form.     The  water  thus  situated 
is  called  water  of  crystallization.     Some  substances  com- 
bine with  water  in  different  proportions,  and  consequently 
assume  different  forms ;  others  crystallize  with  or  without 
water,  with  a  corresponding  diversity  of  form.     These  re- 
sults are  dependent  upon  variations  of  temperature  in  the 
solvent  at  the  period  of  the  crystallization.     At  86°,  sul- 
phate of  soda  crystallizes  without,  at  40°,  with  water  of 
crystallization.     Chloride  of  sodium,  which  is  ordinarily 
anhydrous,  is  made  to  unite  with  water  of  crystallization 
at  8°  below  zero. 

503.  Crystals  usually  retain  within  their  crevices  a  mi- 
nute portion  of  the  solution  in  which  they  have  been  crys- 
tallized.    Hence  the  decrepitation  of  chloride  of  sodium 
and  other  anhydrous  salts  when  heated,  from  the  vapori- 


88  PONDERABLE  MATTER. 

zation  of  the  water  so  retained.     The  larger  the  crystals, 
the  more  they  are  liable  to  this  impurity. 

Of  the  Consequence  of  excluding  the  Air  from  a  saturated 
Solution  of  Sulphate  of  Soda  while  boiling. 

504.  If  a  flask  be  sealed,  so  as  to  be  air-tight,  while 
containing  a  boiling   saturated  solution   of  Glauber's   salt, 
(sulphate  of  soda,)  the  solution  will  remain  liquid,  so  long 
as  undisturbed,  but  on  the  admission  of  the  air,  will  often 
become  a  compact  crystalline  mass  within  a  few  seconds. 
In  other  cases,  it  will  continue  liquid  for  some  time,  even 
for  24  hours,  and  may  then  crystallize  on  being  poured 
out  of  the  flask.     Sometimes  it  crystallizes  in  the  neck  of 
the  vessel  while  the  operator  is  pouring  it  out ;  at  others, 
allowing  a  crystal  or  other  body  to  fall  into  the  solution, 
causes  crystals  to  shoot.     No  satisfactory  explanation  has 
been  afforded  of  this  phenomenon.     It  seems  as  if  the  re- 
pulsive and  attractive  powers  were  so  nearly  balanced  as 
to  enable  a  slight  external  force  to  determine  the  prepon- 
derancy  in  favour  of  the  latter.     That  there  is  an  evolu- 
tion of  caloric,  consequent  to  the  congelation,  is  rendered 
evident  by  a  rise  of  temperature. 

Experimental  Illustration. 

505.  Several  glass  flasks  being  made  about  two-thirds 
full  of  a  saturated  solution  of  Glauber's  salt,  and  sealed 
up  air-tight,  the  solution  remains  liquid  until  the  air  is 
admitted.     It   then  crystallizes  either  spontaneously,  or 
from  slight  causes. 

OF  CHEMICAL  AFFINITY,  OR  HETEROGENEOUS  ATTRACTION. 

506.  This  attraction  is  never  subdued  mechanically,  un- 
less when  nearly  balanced  by  repulsion;  as  in  the  case  of 
compounds  which  may  be  exploded  by  percussion,  (29,)  or 
of  elastic  fluids  combined  with  liquids.  (240.) 

507.  To  sever  elements,  united  by  chemical  affinity,  the 
finest  edge  producible  by  human  art  is  utterly  incompetent. 
Thus,  chalk  consists  of  lime  and  carbonic  acid ;  vermilion, 
of  sulphur  and  mercury.     Yet  when  reduced  to  powders 
perfectly  impalpable,   the   minutest   particle,   whether   of 
chalk  or  vermilion,  contains  the  same  ingredients  as  the 
mass,  and  in  the  same  proportion. 


CHEMICAL  ATTRACTION.  89 

Different  Cases  of  Affinity". 

508.  First  Case — Simple  Combination. — A  and  B,  two 
heterogeneous  substances,  unite  and  form  the  compound 
AB. 

Instances. 

509.  Copper  with  zinc  forms  brass. 

510.  Copper  with  tin  forms  bronze. 

511   Antimony  writh  lead  forms  type  metal. 

512.  Magnesia  with  sulphuric  acid  forms  Epsom  salt,  or 
sulphate  of  magnesia. 

513.  Soda  with  sulphuric  acid  forms  Glauber's  salt,  or 
sulphate  of  soda. 

514.  With  mercury,  various  metals  form  amalgams. 

Experimental  Illustration. 

515.  A  portion  of  gold  leaf,  being  triturated  with  mer- 
cury, disappears,  forming  a  chemical  compound  with  the 
mercury,  in  consequence  of  the  inherent  attraction  or  af- 
finity between  the  heterogeneous  particles. 

516.  Second  Case  of  Affinity. — Called  single  elective  at- 
traction^ or  simple  affinity. 

517.  A  and  B,  two  heterogeneous  particles,  being  united 
in  the  compound  AB,  another  particle,  C,  being  blended 
with  them  in  solution,  unites  with  one  of  them,  as  A,  to 
the  exclusion  of  B. 

518.  In  this  case,  C  is  said  to  decompose  AB,  and  to 
have  a  greater  affinity  for  A  than  for  B. 

Experimental  Illustration. 

519.  Potash  being  added  to  a  solution  of  sulphate  of 
magnesia,  the  magnesia  precipitates  in  white  flocks.     A 
like  result  takes  place,  on  adding  a  solution  of  potash  to  a 
solution  of  sulphate  of  alumina. 

520.  Rationale. — Sulphate  of  magnesia  consists,  as  its 
name  implies,  of  sulphuric  acid  and  magnesia.    The  affini- 
ty existing  between  the  potash  and  the  acid  being  greater 
than  between  the  acid  and  the  magnesia,  the  latter  is  dis- 
placed from  combination,  and,   being  by  itself  insoluble, 
precipitates.     An  analogous  explanation  will  apply  in  the 
case  of  the  alumina.     In  each  case,  the  affinity  ojf  the  acid 

12 


90  PONDERABLE  MATTER. 

for  the  alkali,  predominates  over  that  of  the  acid  for  the 
earth. 

521.  Third  Case  of  Affinity. — Called  double  elective  at- 
traction, or  complex  affinity. 

522.  The  compound  formed  by  the  particles  A  and  B, 
being  blended  in  solution  with  the  compound  formed  by  C 
and  D, — A  combines  with  D,  and  B  with  C. 

Experimental  Illustration. 

A  B  AD 

Sulphate  of  zinc    }  1  Sulphate  of  lead 

being  mixed  with  >  forms  <  and 

Acetate  of  lead,    }  f  Acetate  of  zinc. 

CD  C  B 

523.  Fourth  Case  of  Affinity. — A  and  B  being  in  union, 
C,  added  in  excess,  combines  with  both  A  and  B. 

524.  When  ammonia  is  added  to  certain  solutions  of 
metallic  salts,  those  of  copper  or  silver  for  instance,  it 
operates  at  first  as  the  potash  does  in  the  case  of  single 
elective  attraction  abovementioned,  and  the  oxide  of  cop- 
per or  silver  precipitates.     But  if  the  ammonia  be  added 
in  such  quantity,  as  that,  after  all  the  acid  shall  have  been 
saturated,  there  shall  be  an  excess  of  alkali,  this  excess 
will  combine  with  the  precipitated  metallic  oxide,  forming 
with  it  a  compound  which  is  immediately  dissolved.    Hence 
the  menstruum  which  is  at  first  rendered  turbid,  afterwards 
becomes  clear,  and,  in  the  case  of  the  copper,  assumes  a 
beautiful  and  characteristic  blue  colour. 

Experimental  Illustration. 

525.  Liquid  ammonia  being  poured  into  a  solution  of 
copper,  at  first  precipitates  the  metal  in  greenish  flocks ; 
but,  when  the  alkali  is  added  in  excess,  these  flocks  disap- 
pear, and  a  blue  solution  results. 

Additional  Illustrations  of  Chemical  Affinity. 

526.  In  order  to  show  the  wonderful  power  of  chemical 
reagents  in  producing  striking  changes,  some  additional 
exemplifications  of  chemical  affinity  will  here  be  given. 
This  exhibition  may  excite  curiosity  in  the  learner  and 


CHEMICAL  ATTRACTION.  91 

afford  gratification  to  him,  although  unprepared  to  under- 
stand the  intricate  play  of  affinities  by  which  the  results 
are  accomplished. 

Experiments. 

527.  Silver  precipitated  by  mercury,  mercury  by  copper, 
and  copper  by  iron. 

528.  Conversion  of  two  liquids  into  an  adhesive  mass 
by  mingling  sulphuric  acid  with  a  solution  of  chloride  of 
calcium  or  nitrate  of  lime. 

529.  Solution  of  ferroprussiate  of  potash,  added  to  solu- 
tions of  copper  and  iron. 

530.  Solution  of  chromate  of  potash,  added  to  solutions 
of  lead,  mercury,  and  silver. 

531.  Ammoniacal  nitrate  of  copper  or  silver,  added  to 
arsenious  acid. 

Of  Cohesion  as  an  Opponent  to  Chemical  Combination. 

532.  There  are  many  substances,  among  others  carbon, 
which,  under  certain   forms,  in    consequence  of  greater 
hardness,  are  much  less  susceptible  of  chemical  reaction, 
than  under  others.     Thus  the  diamond,  anthracite,  char- 
coal, and  tinder,  are  varities  of  carbon,  which  are  endowed 
with  a  susceptibility  of  combustion  inversely  as  their  hard- 
ness.    Tinder  is  proverbially  ready  to  take  fire,  while  the 
diamond  is  only  to  be  ignited  by  the  aid  of  extreme  heat, 
and  an  unusual  supply  of  oxygen.     Every  body  knows 
how  much  less  susceptible  of  being  acted  upon  by  solvents, 
are  bricks,  porcelain,  or  stone  ware,  than  the  earthy  mate- 
rials out  of  which  they  are  made.    In  these  cases,  it  would 
really  appear  that  the  attraction  between  the  homogeneous 
atoms  counteracts  the  heterogeneous  affinity  which  would 
sever  them.     Yet  I  conceive  it  to  be  an  error  to  confound 
the  obstruction  to  chemical  reaction  thus  created,  with  that 
which  arises  from  the  restriction  of  the  surface  in  contact 
with  the  solvent.    Other  things  being  equal,  there  will  evi- 
dently be  more  action  in  proportion  as  the  points  of  con- 
tiguity are  multiplied,  and  vice  versa.     Thus  the  action  of 
an  acid  will  be  less  rapid  upon  a  metallic  ball,  than  upon 
the  same  weight  of  metal  in  the  state  of  foil,  fine  wire,  or 
turnings;    although   the   attraction    of  the   homogeneous 


92  PONDERABLE  MATTER. 

particles  is  quite  as  energetic  in  the  one  case  as  in  the 
other. 

Effects  of  Mechanical  Division  experimentally  illustrated. 

533.  If  a  ball  of  brass  be  put  into  one  glass,  and  only 
half  its  weight  of  brass  filings  or  turnings  into  another,  on 
adding  nitric  acid  to  both,  a  violent  effervescence  will 
ensue  in  the  one,  while  in  the  other,  the  reaction  will  hardly 
be  discernible. 

Influence  of  Solution  in  promoting  Chemical  Reaction,  expe 
rimentally  illustrated. 

534.  Tartaric  acid  and  a  carbonate,  although  intimately 
intermingled  in  a  pulverulent  state,  do  not  react  until  moist- 
ened, when  a  lively  effervescence  ensues. 

Exception  to  the  Law  that  Chemical  Action  requires  Fluidity, 
experimentally  illustrated. 

535.  If  slaked  lime  and  muriate  of  ammonia  in  powder 
be  mixed,  the  pungent  fumes  of  ammonia  will  be  perceived. 

Tables  of  Affinity. 

536.  These  consist  of  the  names  of  a  series  of  sub- 
stances, placed  in  a  column,  in  the  order  of  their  affinity 
for  any  one  substance  of  which  the  name  is  at  the  head  of 
the  column.     The  following  is  an  example: — 

Sulphuric  Acid. 

Baryta, 

Strontia, 

Potash, 

Soda, 

Lime, 

Magnesia, 

Ammonia. 


DEFINITE  PROPORTIONS.  93 

SECTION  II. 

OF  DEFINITE  PROPORTIONS. 

537.  The  proportions  have  been  long  known  to  be  in- 
variable, in  which  substances  must  be  mixed  in  order  to 
saturate  each  other,  or  to  produce  a  compound  in  which 
the  peculiar  characters,  or  affinities  of  the  ingredients,  are 
extinguished. 

538.  When  substances  combine  in  other  proportions 
than  those  of  saturation,  their  ratio  is  no  less  definite  and 
constant. 

539.  There  is  not  in  any  case,  except  the  peculiar  one 
of  solution,  an  indefinite  gradation  in  the  proportions  in 
which  bodies  combine.     There  are  rarely  more  than  four 
gradations. 

540.  The  number,  representing  the  least  proportion  in 
which  a  substance  is  known  to  combine,  will,  in  a  great 
majority  of  cases,  divide  the  numbers  representing  the 
greater  proportions  without  a  fraction;   and  where  this 
result  is  unattainable,  it  will  still  be  found  that  the  larger 
proportion  may  be  divided  by  the  half  of  the  lesser  without 
a  remainder. 

541.  Let  A,  B,  and  C  be  certain  substances,  and  let  X, 
Y,  and  Z  be  other  substances,  severally  having  an  affinity 
for  either  A,  or  B,  or  C.    Let  each  of  the  former  and  each 
of  the  latter  be  combined  in  the  least  possible  proportion. 
Consequently,  the  least  combining  proportion  of  each  sub- 
stance will  be  found  three  times.     It  will  appear  that  the 
proportions  of  A,  B,  and  C  found  by  combining  them  with 
X,  will  be  in  the  same  ratios  to  each  other,  as  the  propor- 
tions found  by  combining  them  with  Y,  or  Z;  and  reci- 
procally, that  the  proportions  of  X,  Y,  and  Z,  will  have  the 
same  ratios,  whether  ascertained  by  their  combination  with 
A,  B,  or  C. 

542.  When,  instead  of  ascertaining  the  least  combining 
proportions  of  six  substances,  the  experiment  has  been  ex- 
tended to  any  larger  number,  the  same  uniformity  has 
been  found  to  prevail  in  the  ratios  of  the  numbers  repre- 
senting those  proportions.     It  has  also  been  found  that 
when  numbers  are  ascertained  which  express  the  ratio  of 
the  least  combining  proportions  of  "a  variety  of  substances 
to  any  one  substance,  as  for  instance  to  oxygen,  those 


94  PONDERABLE  MATTER. 

numbers  will  express  the  ratios  of  the  least  combining  pro- 
portions of  the  substances  in  question,  to  each  other. 

543.  Numbers  representing  least  combining  proportions 
are  called  chemical  equivalents.     As  they  are  merely  ex- 
pressive of  ratio,  they  may  be  multiplied  by  any  common 
multiplier,  or   divided  by  any  common  divisor,  without 
affecting  their  correctness. 

544.  They  are  usually  so  computed  as  to  make  the 
equivalent  of  oxygen,  or  of  hydrogen  =  1.     As  the  equi- 
valents of  these  substances  are  as  1  to  8,  it  follows,  that  if 
hydrogen  be  represented  by  unity,  oxygen  will  be  8.     If 
oxygen  be  unity,  hydrogen  will  be  0.125,  or  one-eighth  of 
one.    Consequently,  equivalents,  formed  upon  either  basis, 
may  be  converted  into  those  corresponding  with  the  other, 
either  by  multiplying  or  dividing  by  8. 

545.  By  Berzelius,  Wollaston,  and  Thomson,  oxygen 
has  been  made  the  standard.    Berzelius  assumes  it  at  100, 
Wollaston  at  10,  and  Dr.  Thomson  at  1.     The  only  dif- 
ference between  the  equivalents  founded  upon  these  num- 
bers, is  in  the  position  of  the  decimal  point. 

Of  Tables  of  Chemical  Equivalents* 

546.  In  these,  the  equivalents  of  all  known  bodies,  so 
far  as  ascertained,  are  arranged  alphabetically.     Such  ta- 
bles are  of  great  utility  in  practical  chemistry.     The  ope- 
rative chemist  may  frequently  resort  to  them  with  advan- 
tage.    They  enable  him  to  store  his  memory  with  data 
adequate  to  the  solution  of  a  great  number  of  questions 
which  must  necessarily  arise.     If  he  wishes  to  know  how 
much  of  any  two  substances  he  must  take  to  form  a  third, 
he  has  only  to  recollect,  or  to  look  for,  their  equivalents  in 
the  table,  and  seek  a  solution  by  the  rule  of  three.     For  as 
the  equivalents  of  the  substances  are  to  each  other,  so  are 
the  quantities  of  them  to  be  used.     Should  it  be  an  object 
to  produce  only  a  certain  weight  of  a  compound,  then,  as 
the  equivalent  of  the  compound  is  to  that  of  either  of  the 
ingredients,  so  is  the  weight  of  the  compound  required,  to 
the  requisite  weight  of  either  ingredient. 

547.  In  order  to  know  how  much  of  the  proper  mate- 
rials he  must  use  to  effect  a  decomposition,  he  has  only 
to  employ  them  in  the  ratio  of  their  respective  equivalents. 

*  See  Appendix  for  a  Table  of  Equivalents. 


DEFINITE  PROPORTIONS.  95 

548.  Moreover,  when  the  proportions,  afforded  by  ana- 
lysis, do  not  harmonize  with  well  ascertained  equivalents, 
we  are  warned  of  the  existence  of  some  inaccuracy,  which 
in  many  cases  may  be  safely  corrected  so  as  to  make  the 
results  accord  with  them. 

Wollastorfs  Scale  of  Equivalents. 

549.  This  instrument  is  so  constructed  that  the  computation  requisite  in 
using  the  equivalents  is  performed  by  a  slide.     It  has  been  mentioned  that 
the  equivalents  may  be  expressed  in  any  numbers  having  the  same  ratios  to 
each  other  as  the  least  combining  proportions  of  the  substances  which  they 
represent.     The  slide  enables  us  to  adopt  any  such  numbers  as  may  be  con- 
venient.    Equal  distances  on  the  slide  give  the  same  ratios  in  different  num- 
bers.    If,  by  moving  the  slide,  we  vary  one  equivalent  to  100,  for  instance, 
the  other  equivalents  vary  proportionally. 

Of  the  Atomic  Theory. 

550.  Extension  has  been  proved  to  be  infinitely  divisible,  and  it  is  not 
difficult  to  suppose  that  the  matter,  comprised  within  any  given  limits,  may 
be  susceptible  of  as  many  subdivisions  as  the  space  in  which  it  is  contained. 
On  the  other  hand,  it  is  obvious,  that  mechanical  division  must  be  limited 
by  the  imperfection  of  the  edges  or  surfaces  employed  to  accomplish  it. 

551.  Were  atoms  chemically  divisible  ad  infmitum,  any  one  substance, 
however  small  in  quantity,  might  be  diffused,  in  a  state  of  chemical  combi- 
nation, throughout  any  other,  having  an  affinity  for  it,  however  great ;  for 
as  no  one  particle  in  the  latter  would  exercise  a  stronger  affinity  than  an- 
other, it  would  be  unreasonable  to  suppose  that  each  should  not  have  its 
share.     That  such  a  diffusion  is  impracticable  must  be  evident  from  the 
smallness  of  the  number  of  definite  proportions  to  which  substances  in 
combining  are  restricted,  as  already  mentioned  when  upon  the  subject  of 
equivalents.     Hence  elementary  atoms  are  not  considered  as  liable  to  an 
unlimited  subdivision,  either  by  chemical  or  mechanical  agency .v  (539.) 

552.  The  ratios  of  the  equivalent  numbers  are  supposed  to  be  dependent 
on,  and  identical  with,  those  of  the  weights  of  the  integrant  atoms  of  the 
substances  to  which  they  appertain.    Thus  the  fact  that  32  parts  by  weight 
of-soda  will  saturate  as  much  of  any  acid  as  48  parts  of  potash,  is  explained 
by  supposing  that  the  weights  of  the  smallest  atoms  of  those  alkalies  which 
can  exist,  are  to  each  other  as  32  to  48. 

553.  In  like  manner  it  is  explained  that,  when  neutral  salts  are  made  re- 
ciprocally to  decompose  each  other,  no  excess  of  either  ingredient  is  in  any 
case  observable.     The  lime  in  nitrate  of  lime  is  to  the  potash  in  an  equiva- 
lent weight  of  the  sulphate  of  potash,  as  28  to  48,  yet  neither  is  the  lime 
incompetent  to  take  the  place  of  the  potash,  nor  is  there  too  much  potash  to 
take  the  place  of  the  lime.     This  result  is  intelligible,  if  we  suppose  that, 
when  quantities  just  adequate  for  reciprocal  decomposition  are  employed, 
there  is  an  equal  number  of  atoms  of  each  salt ;  the  one  containing  as 
many  atoms  of  potash  weighing  48,  as  the  other  contains  atoms  of  lime 
weighing  28. 

554.  The  "same  explanation  applies  to  the  fact  that,  while  the  sulphuric 
acid  in  the  sulphate  of  potash  is  to  the  nitric  acid  in  the  nitrate  of  lime  as  40 


96  PONDERABLE  MATTER. 

to  54,  yet  there  is  neither  too  much  of  the  latter  acid  nor  too  little  of  the  for- 
mer, to  produce  neutral  compounds  with  the  bases  to  which  they  are  se- 
verally transferred. 

555.  On  account  of  the  hypothetical  association  of  the  numbers,  repre- 
senting the  least  proportions  in  which  bodies  are  known  to  combine,  with 
the  supposed  relative  weight  of  their  atoms,  those  numbers  are  as  well 
known  by  the  appellation  of  atomic  weights,  as  by  that  of  chemical  equi- 
valents. , 

Of  Chemical  Symbols. 

556.  I  shall  translate  from  Berzelius  an  account  of  the  symbols  which  he 
has  devised,  and  which  it  would  be  well  to  understand,  as  they  will  often  be 
met  with.     Objections  have  been  made  to  some  part  of  his  plan,  but  in  ge- 
neral I  believe  it  will  be  expedient  to  adhere  to  it ;  since  whatever  Berze- 
lius recommends,  awakens  the  attention  of  chemists  universally,  and  must 
cause  his  symbols  to  be  generally  understood  throughout   the   chemical 
world. 

557.  "  We  select  (says  he)  as  symbols  the  initial  letters  of  the  Latin 
names  of  bodies.     When  the  names  of  several  bodies  have  the  same  initial, 
we  add  to  each  a  letter  which  it  has  not  in  common  with  the  rest ;  as,  for 
instance,  C  signifies  carbon,  Cl  chlorine,  Cr  chromium,  Cu  copper,  Co  co- 
balt.    When,  however,  the  names  of  a  metallic  and  non-metallic  element 
commence  with  the  same  letter,  no  additional  letter  is  added  to  the  latter. 
But  when  two  non-metallic  elements  have  a  common  initial,  it  is  necessary 
to  distinguish  one  by  means  of  an  additional  letter.     Thus,  to  distinguish 
chlorine,  bromine,  and  silicon,  severally,  from  carbon,  boron,  and  sulphur, 
the  symbols  of  the  former  are  Cl,  Br,  and  Si,  while  those  of  the  latter  are, 
simply  C,  B,  and  S. 

558.  "  The  number  of  atoms  is  designated  by  cyphers.    A  cypher  placed 
to  the  left  multiplies  all  the  symbols  to  the  right,  as  far  as  the  first  cross,  -j- 
or  the  whole  formula.     A  little  cypher,  situated  to  the  right  of  a  symbol, 
and  a  little  above  its  level,  multiplies  that  symbol  only.     Thus  S2O5  sig- 
nifies one  atom  of  hyposulphuric  acid,  consisting  of  two  atoms  of  sulphur 
and  five  of  oxygen;  while  2S2O5  signifies  two  atoms  of  the  same  acid.    In 
such  cases  as  that  just  cited,  in  which  two  atoms  of  the  radical  are  united 
with  one,  three,  or  five  of  oxygen,  the  expression  for  the  former  would  be 
abbreviated  advantageously  by  having  a  specific  sign  for  a  double  atom. 
The  sign  which  I  have  adopted  for  this  purpose,  is  a  dash  across  the  lower 
part  of  the  symbolic  letter.     Thus  P  signifies  a  single  atom,  P*  a  double 
atom  of  phosphorus.     Compound  atoms  of  the  first  order  are  expressed  as 
in  the  following  example  of  sulphate  of  copper  Cu  O-J-SO3.     The  trisul- 
phate  of  the  sesquioxide  of  iron  would  be  expressed  by  2Fe  O3-f-3SO3. 

559.  "  It  may  be  expedient  to  designate  the  number  of  atoms  of  oxygen 
by  dots  placed  over  the  letters  symbolic  of  radicals.     Thus  we  may  desig- 
nate the  sulphate  of  copper  by  Cu  S,  the  trisulphate  of  the  sesquioxide  of 
iron,  by  2  Fe  S3." 

*  Instead  of  placing  the  dash  across  the  lower  part  of  the  letter,  it  is  generally 
placed  under  it,  as  the  former  mode  requires  type  cast  for  the  purpose. 


DEFINITE  PROPORTIONS. 


97 


List  of  the  Atomic  Weights  of  the  Simple  Ponderable  Substances, 
together  with  their  Symbols. 

560.  As  the  atomic  numbers  are  practically  useful,  enabling  us  to  know 
the  proportions  in  which  substances  are  combined,  or  in  which  they  should 
be  used  to  produce  compounds,  it  is  advantageous  to  commit  them  to  me- 
mory as  far  as  possible.     The  whole  number  of  substances  recognised  as 
elementary,  agreeably  to  the  present  state  of  our  knowledge,  is  fifty-four. 
Of  these,  little  more  than  half  are  of  sufficiently  frequent  recurrence  either 
in  speculation  or  in  practice,  to  make  it  desirable  to  remember  their  num- 
bers.    I  will  quote  them,  therefore,  in  two  distinct  tables.     Those  of  which 
a  knowledge  is  likely  to  be  rarely  in  demand,  I  have  subjoined  in  smaller 
type.     The  symbols  are  given  in  a  separate  column.     In  obedience  to  the 
example  of  the  British  chemists,  I  employ  Po  and  So,  instead  of  K  and  Na, 
as  the  symbols  of  potassium  and  sodium. 

At. 
Wts. 
6 

12 

-       202 
14 
8 

16 
99 
40 
40 
8 

108 
24 
44 
16 
64 
59 
32 

-  100 

53 
52 
60 
24 
95 

-  217 

69 
32 
34 

561 .  It  appears  from  some  experiments  made  by  Messrs.  Petit  and  Dulong,  that  the 
capacities  for  heat,  or  specific  heats,  of  all  elementary  atoms  are  the  same;  so  that 
if  the  specific  heat  of  any  one  congeries  of  atoms  be  less  than  that  of  another  having 
the  same  weight,  it  is  because  the  atoms  of  the  one  being  heavier  than  those  of  the 
other,  there  are  fewer  of  them  in  the  same  weight.     Hence  the  capacities,  or  spe- 
cific heats,  of  equal  volumes  of  elementary  substances  are  greater,  as  the  weights 
of  their  atoms  are  less;  so  that  if,  in  the  case  of  each,  its  atomic  weight  be  multi- 
plied by  its  specific  heat,  the  product  will  in  general  be  so  nearly  the  same,  that  the 
difference  may  be  ascribed  to  the  inaccuracy  unavoidable  in  experimental  investi- 
gations. 

562.  Respecting  this  highly  important  and  interesting  inference  of  Petit  and  Du- 
long,  Professor  A.  D.  Bache  has  endeavoured  to  show  in  an  article  published  in  tha 

13 


Symbol. 

Aluminium 

Al       - 

Antimony 

Sb      - 

Arsenic 

As      - 

Barium 

Ba      - 

Bismuth 

Bi       - 

Boron 

B        - 

Bromine 

Br      - 

Calcium 

Ca      - 

Carbon 

C       - 

Chlorine 

Cl      - 

Copper 

Cu      - 

Fluorine 

F 

Gold 

Au     - 

Hydrogen 

H       - 

Iodine 

I 

Iron 

Fe      - 

Lead 

Pb      - 

Cadmium 

Cd 

Cerium 

Ce 

Chromium 

Cr 

Cobalt 

Co 

Columbium 

Ta 

Glucinium 

G 

Iridium 

Ir 

Manganese 

Mn 

Molybdenum 
Nickel 

Mo 

Ni 

At. 

Wts. 

Symbol. 

14 

Lithium 

L 

64 

Magnesium 

Mg 

38 

Mercury 

Hg 

69 

Nitrogen 

N 

71 

Oxygen 

O 

11 

Phosphorus 

P 

78 

Platinum 

PI 

20 

Potassium 

Po 

6 

Selenium 

Se 

36 

Silicon 

Si 

32 

Silver 

Ag 

18 

Sodium 

So 

200 

Strontium 

Sr 

1 

Sulphur 

S 

126 

Tellurium 

Te 

28 

Tin 

Sn 

104 

Zinc 

Zn 

56 

Osmium 

Os 

46 

Palladium 

Pd 

28 

Rhodium 

R 

30 

Thorium 

Th 

185 

Titanium 

Ti 

18 
99 

Tungsten 
Uranium 

W 

U 

28 

Vanadium 

V 

48 

Yttrium 

Y 

30 

Zirconion 

Zr 

98  PONDERABLE  MATTER. 

Journal  of  the  Academy  of  Natural  Sciences,  that  multiplying  the  equivalents  of 
twelve  principal  metals  into  their  specific  heat,  gives  results  so  widely  deviating 
from  uniformity  as  to  take  all  plausibility  from  the  hypothesis  that  the  atoms  of  sim- 
ple bodies  have  the  same  specific  heat. 

5(!3.  Dr.  Thomson  has  observed  that  this  law  is  more  likely  to  be  true,  since  it 
holds  good  without  doubt  in  the  case  of  the  gases ;  and  that  if  it  be  true  we  have 
only  to  divide  the  specific  heat  of  hydrogen  by  the  atomic  weight  of  any  body,  to 
find  its  specific  heat.  Moreover  that  the  specific  heats  thus  found  agree  very  nearly 
with  those  ascertained  experimentally. 

5(54.  From  the  researches  of  Faraday,  it  appears  that  the  quantity  of  the  voltaic 
fluid  given  out  during  the  solution  of  various  metals,  is  in  the  ratio  of  their  atomic 
weights.  It  would  seem,  therefore,  as  if  the  imponderable  atmospheres,  both  of 
caloric  and  electricity,  are  held  by  atoms  in  the  same  equivalent  proportion. 


SECTION  III, 

OF  SPECIFIC  GRAVITY. 

565.  A  clear  idea  of  specific  gravity  is  indispensable  to  a  chemist.  Gravity 
and  weight,  are  synonymous  words ;  but  the  term  specif  c  gravity  is  used 
to  signify  the  ratio  of  weight  to  bulk.     Hence  the  object  of  all  the  processes 
for  ascertaining  specific  gravities,  is  either  to  ascertain  the  weight  of  a  known 
bulk,  or  the  bulk  of  a  known  weight;  for  whether  the  substances  whose 
specific  gravities  are  to  be  found  be  reduced  to  the  same  weight  and  then 
measured,  or  be  reduced  to  the  same  bulk  and  then  weighed,  the  ratio  of 
their  weights  to  their  bulks  will  be  discovered.     If  reduced  to  the  same  bulk 
and  weighed,  their  specific  gravities  will  be  directly  as  the  weights.     If 
reduced  to  the  same  weight  and  measured,  their  specific  gravities  will  be 
inversely  as  their  bulks  thus  ascertained. 

566.  Supposing  a  like  bulk  of  each  kind  of  matter  in  nature  to  be  weigh- 
ed, the  results,  numerically  stated,  would  represent  their  specific  gravities. 
But  since  it  is  not  possible  to  procure  an  exactly  similar  bulk  of  each  kind 
of  matter,  it  is  necessary  to  resort  to  another  mode  of  reducing  their  bulks 
to  a  common  measure.     The  method  adopted  in  the  case  of  solids  and  li- 
quids, is  to  divide  the  weight  of  a  given  bulk  of  each  body  of  which  the 
specific  gravity  is  to  be  found,  by  the  weight  of  a  like  bulk  of  water.     This 
in  fact  may  be  stated  as  the  general  rule  for  ascertaining  specific  gravities. 

567.  Thus  on  dividing  the  weight  of  any  bulk  of  copper  by  the  weight 
of  a  like  bulk  of  water,  the  quotient  is  9.     This,  therefore,  is  received  as 
the  specific  gravity  of  copper.      By  a  similar  procedure,  in  the  case  of 
silver,  the  quotient  is  10.5,  in  the  case  of  mercury  13,6,  in  the  case  of  gold, 
19.3 :    consequently,   these  numbers  are  considered  as  representing  the 
specific  gravities  of  those  metals. 

568.  If  the  body  be  lighter  than  water,  as  in  the  case  of  cork  which  is 
only  about  one-fifth  as  heavy,  the  quotient,  being  less  than  one,  is  ex- 
pressed by  a  decimal  fraction.     Thus  the  specific  gravity  of  cork  may  be 
stated  to  be  .2. 

569.  The  gravity  of  water  has  been  assumed  as  the  standard,  because 
this  liquid  may  always  be  obtained  sufficiently  pure ;  and  it  is  generally 
easy  to  ascertain  thes  weight  of  a  quantity  of  it,  equal  in  bulk  to  any  other 
body. 

570.  The  weight  of  a  quantity  of  water,  equal  to  the  body  in  bulk,  is 


SPECIFIC  GRAVITY. 


99 


equal  to  the  resistance  which  the  body  encounters  in  sinking  in  water. 
Hence,  if  we  can  ascertain,  in  weight,  what  is  necessary  to  overcome  the 
resistance  which  a  body  encounters  in  sinking  in  water,  and  divide  by  the 
weight  thus  ascertained,  the  weight  of  the  body,  we  shall  have  its  specific 
gravity. 

571.  In  the  case  of  a  body  which  will  sink  of  itself,  the  resistance  to  its 
sinking  is  what  it  loses  of  its  weight  when  weighed  in  water. 

572.  In  the  case  of  a  body  which  will  not  sink  of  itself,  the  resistance 
to  its  sinking  is  equivalent  to  its  own  weight,  added  to  the  weight  which 
must  be  used  to  make  it  sink. 

Experimental  Demonstration  that  the  Resistance  which  a  Body  encoun- 
ters in  sinking  in  any  Liquid,  is  just  equivalent  to  the  Weight  of  a 
portion  of  the  Liquid  equalling  the  Body  in  bulk. 

573.  This  proportion  may  be  experimentally  demonstrated,  by  means  of 
the  apparatus  represented  by  the  following  figure. 

574.  The  cylinder,  represented  as  surrounded  by 
the  water  of  the  vase,  is  made  to  fit  the  cavity  of  the 
cylinder  suspended  over  it  so  exactly,  that  it  enters 
the  cylinder  with  difficulty,  on  account  of  the  in- 
cluded air,  which  can  only  be  made  to  pass  by  it 
slowly.     It  must,  therefore,  be  evident,  that  the  ca- 
vity of  the  hollow  cylinder  is  just  equal  in  bulk  to 
the  solid  cylinder. 

575.  Both   cylinders  (suspended  as   seen   in   the 
figure)  being  counterpoised  accurately  upon  a  scale 
beam,  let  a  vessel  of  water  be  placed  in  the  situation 
of  the  vase.     It  must  be  evident,  that  the  equiponde- 
rancy  will  be  destroyed,  since  the  solid  cylinder  will 
be  buoyed  up  by  the  water.     If  water  be  now  poured 
into  the  hollow  cylinder,  it  will  be  found  that,  at  the 
same  moment  when  the  cavity  becomes  full,  the  equi- 
ponderancy  will  be  restored,  and  the  solid  cylinder 
sunk  just  below  the  surface  of  the  water. 

576.  Hence  it  appears  that  the  resistance  which 
the  solid  cylinder  encounters  in  sinking  in  the  water, 
i§  overcome  by  the  weight  of  a  quantity  of  water 
equal  to  it  in  bulk.    It  must  be  evident,  that  the  same 

would  be  true  of  any  other  body,  and  of  any  other  liquid. 

577.  Rationale. — When  a  solid  body  is  introduced  into  an  inelastic 
solid,  on  withdrawing  it  a  hole  is  left,  which  remains  vacant  of  the  solid 
matter ;  but  no  sooner  is  a  body  which  has  been  introduced  into  a  liquid 
withdrawn,  than  the  liquid  is  found  to  fill  up  the  space  from  which  it  had 
been  removed. 

578.  It  is  evident  that  the  force  which  liquids  thus  exert  to  re-enter  any 
space  within  them  from  which  they  are  forcibly  excluded,  is  precisely  equal 
to  the  weight  of  a  quantity  of  the  liquid  commensurate  with  that  space  ; 
since,  when  the  space  is  reoccupied  by  the  liquid,  the  equilibrium  is  restored. 
Consequently,  every  body,  introduced  into  a  liquid,  experiences  from  it  a 
resistance  equal  to  the  weight  of  a  quantity  of  the  liquid,  commensurate 
with  the  cavity  which  would  be  produced,  supposing  the  liquid  frozen  about 
the  solid  mass,  split  open  so  as  to  remove  it,  and  the  fragments  put  together 
again ;  and  the  cavity  thus  created  must  obviously  be  exactly  equal  to  the 


100 


PONDERABLE  MATTER. 


bulk  of  the  body.  It  follows,  therefore,  that  the  resistance  which  any  body 
encounters  in  sinking  within  a  liquid,  is  equivalent  to  the  weight  of  a  quan- 
tity of  the  liquid,  equal  in  bulk  to  the  body. 

Method  of  ascertaining  the  Specific  Gravity  of  a  Body  heavier  than 

Water. 

579.  Let  the  glass  stopple,  represented  in  the  adjoining 
figure,  be  the  body.      First  counterpoise  the  stopple  by 
means  of  a  scale  beam  and  weights,  suspending  it  by  a  fine 
metallic  wire.     Place  under  the  stopple  a  vessel  of  pure 
water,  at  the  temperature  of  60°,  and  lower  the  beam,  so 
that  if  the  stopple  were  not  resisted  by  the  water,  it  would 
be  immersed.     Add  just  as  much  weight  as  will  counteract 
the  resistance  which  the  water  opposes  to  the  immersion  of 
the  stopple,  and  render  the  beam  again  horizontal.    Divide 
the  weight  by  which  the  stopple  had  been  previously  coun- 
terpoised, by  the  weight  thus  employed  to  sink  it,  and  the 
quotient  will  be  the  specific  gravity. 

580.  Rationale. — The  weight  requisite  to  sink  the  stop- 
ple measures  the  resistance  to  its  being  sunk  in  the  water ; 

and  this  it  has  been  shown  is  equal  to  the  weight  of  a  bulk  of  water  equal  to 
that  of  the  stopple.  Of  course,  pursuant  to  the  general  rule,  it  is  only  ne- 
cessary to  see  how  often  this  weight  is  contained  in  the  weight  of  the  stop- 
ple, to  ascertain  its  specific  gravity. 

Method  of  ascertaining  the  Specific  Gravity  of  a  Body  lighter  than 

Water. 

581.  Let  a  small  glass  funnel  be  suspended  from  a  scale 
beam,  and  counterpoised  so  as  to  be  just  below  the  surface 
of  some  water  in  a  vase,  as  represented  in  the  diagram. 

582.  If,  while  thus  situated,  a  body  lighter  than  water,  a 
small  cork  for  instance,  be  thrown  up  under  the  funnel,  the 
equilibrium  will  be  subverted.    Ascertain  how  much  weight 
will  counteract  the  buoyancy  of  the  cork,  add  this  to  its 
weight,  and  divide  its  weight  by  the  sum.     The  quotient 
will  be  the  answer. 

583.  Rationale. — The  force  with  which  the  cork  rises 
against  the  funnel,  is  equal  to  the  difference  between  its 
weight  and  the  weight  of  the  bulk  of  water  which  it  dis- 
places.     Of  course,  ascertaining  the  force  with  which  it 

:===^^  rises  by  using  just  weight  enough  to  counteract  it,  and 
adding  this  weight,  so  ascertained,  to  that  of  the  cork,  we 
have  the  weight  of  a  bulk  of  water,  equal  to  the  bulk  of  the  cork.  By  this 
weight,  dividing  the  weight  of  the  cork  agreeably  to  the  general  rule,  the 
specific  gravity  of  the  cork  will  be  found. 

Method  of  ascertaining  the  Specific  Gravity  of  a  Liquid. 

•  584.  Let  the  stopple  be  counterpoised,  exactly  as  as  above  directed,  (579,) 
excepting  that  it  is  unnecessary  to  take  any  account  of  the  counterpoising 
weight. 

585.  Having,  in  like  manner,  ascertained  how  much  weight  will  sink  it 


k=x 


SPECIFIC  GRAVITY.  101 


i 


in  the  given  liquid,  divide  this  by  the  weight  required  to  sink  it  in  the  water. 
The  quotient  will  be  the  specific  gravity  sought. 

586.  Rationale. — It  has  been  proved  that  the  resistance  to  the  sinking  of 
a  body  in  any  liquid,  is  precisely  equal  to  the  weight  of  a  bulk  of  the  liquid, 
equal  to  the  bulk  of  the  body.     Ascertaining  the  resistance  to  the  immer- 
sion of  the  same  body  in  different  liquids,  is,  therefore,  the  same  as  ascer- 
taining the  weights  of  bulks  of  those  liquids,  equal  to  the  bulk  of  the  body, 
and,  of  course,  to  each  other.     And  if  one  of  4he  liquids  be  water,  di- 
viding by  the  weight  of  this  the  weights  of  the  others,  gives  their  specific 
gravities. 

587.  If  the  stopple  be  so  proportioned  as  to  lose  just  one  thousand  grains 
by  immersion  in  water,  division  is  unnecessary ;  as  the  weight  of  the  liquid 
will  be  obtained  in  grains,  which  are  thousandths  by  the  premises.     A 
piece  of  metal  exactly  of  the  same  weight  as  the  stopple,  may  be  employed 
as  its  counterpoise. 

588.  In  these  experiments,  the  liquid  should  be  as  near  60°  of  Fahren- 
heit's thermometer  as  possible.  . 

Hydrometers  for  Alcohol,  for  Acid,  Saline,  and  other  Solutions,  and  for  Vegetable 

Infusions. 
A  C 


miiiiiiiiffliiiiiiiiiiiiiiiiiiiiiiiiiiiiipiiiiiimfflfflnniininniiiiiiiiiiiiniiiiiiiiil 


589.  In  these  a  constant  weight  is  used  to  a  certain  extent,  and  the  differences  of 
gravity  are  estimated  by  the  quantity  of  the  stem  immersed.     In  those  instruments 
of  this  construction  where  several  weights  are  employed,  the  effect  is  the  same  as 
if  the  stem  of  the  instrument  were  lengthened  as  many  times  as  the  number  of  the^ 
weights  attached  to  it. 

r>l»0.  The  preceding  engraving  represents  three  hydrometers,  A,  B,  and  C,  contained 
in  glass  vessels.     B  and  C  are  of  glass,  and  A  of  metal. 

591.  B  is  intended  for  liquids  heavier  than  water;  C,  for  those  which  are  lighter. 
In  each,  the  graduation  commences  at  that  point  of  the  stem,  to  which  the  instru- 
ment sinks  in  distilled  water.    It  must  of  course  commence  at  the  top  of  the  stem  for 
liquids  heavier  than  water,  and  at  the  bottom  of  the  stem  for  liquids  lighter  than 
water.     In  the  latter  case,  as  in  that  of  spirituous  liquors  or  ethers,  the  strength 
being  greater  as  the  liquid  is  lighter,  more  of  the  stem  is  immersed  in  proportion  as 
the  liquid  is  stronger;  but  the  opposite  is  true  in  the  case  of  acid  and  saline  solu- 
tions, or  infusions  of  vegetable  matter;  the  more  the  stem  emerges  from  these,  the 
heavier  and  of  course  the  stronger  they  are.    The  instruments  are  represented  as 
when  swimming  in  pure  water. 

592.  A  is  an  hydrometer  of  a  form  much  used  in  this  country  and  in  England,  both 
for  spirit  and  infusions  of  vegetable  matter.     The  stem  is  virtually  lengthened  by 
the  use  of  several  small  weights,  which  may  be  slipped  on  and  off  at  pleasure. 


102 


PONDERABLE  MATTER, 


593.  The  whole  difference  between  the  weight  of  water  and  that  of  the  strongest 
spirit  is  equal  to  about  two  parts  in  ten.     Of  course,  an  hydrometer  for  spirit  should 
have  on  its  stem  a  scale  of  more  than  two  hundred  parts,  in  order  to  give  the  specific 
gravity  of  any  liquid  consisting  of  water  and  alcohol.     To  render  such  graduation 
sufficiently  discernible,  the  stem  would  have  to  be  of  very  inconvenient  length. 
This  is  obviated  by  using  different  weights.     When  the  heaviest  weight  is  upon  the 
stem,  the  whole  of  the  stem  stands  above  the  surface  in  distilled  water.     When  the 
liquid  contains  enough  spirit  to  allow  the  whole  of  the  stem  to  sink  in  it,  while' sup- 
porting this  weight,  a  lighter  weight  may  be  used ;  and  when  the  stem  again  would 
be  wholly  merged,  this  last  mentioned  weight  may  be  exchanged  for  one  still  lighter. 
Supposing  the  stem  graduated  into  fifty  parts,  three  weights  would  give  fifty  degrees 
each,  and  the  stem  unloaded,  fifty  more.     Were  the  stem  graduated  into  ten  parts, 
nineteen  weights  would  give  one  hundred  and  ninety  parts,  and  the  stem  unloaded, 
ten  more. 

594.  An  instrument,  sometimes  called  a  saccharometer,  but  precisely  similar  in 
principle,  is  used  for  infusions  of  vegetable  matter,  especially  for  the  wort  of  brewers 
and  distillers,  excepting  that  the  scale  begins  at  the  top  of  the  stem,  with  a  line 
which  coincides  with  the  surface  of  pure  water,  at  sixty  degrees  Fahrenheit,  when 
the  hydrometer  is  immersed  in  it.     When  the  infusion  is  strong  enough  to  support 
the  whole  of  the  stem  above  its  surface,  a  weight  is  to  be  added  heavy  enough  to 
bring  the  graduated  part  of  the  stem  into  the  liquid.     And,  in  like  manner,  as  the 
infusion  is  found  stronger,  weights  still  heavier  must  be  added;  the  process  being 
perfectly  analogous  to,  bat  the  converse  of  that  described  in  the  case  of  alcohol. 

Nicholson's  Gravimeter  ^  for  ascertaining  the  Specific  Gravity  of  Solids,  either  heavier 
or  lighter  than  Water. 

595.  The  accompanying  cut  is  a  representation  of  Nicholson's 
gravimeter,  the  construction  of  which  is  sufficiently  obvious. 

596.  On  the  upper  scale  of  the  instrument,  whilst  floating  in 
water,  place  any  body,  the  specific  gravity  of  which  is  to  be 
found — a  piece  of  coin  for  instance — and  add  as  much  weight 
to  the  same  scale  as  will  sink  the  gravimeter,  until  a  mark, 
purposely  made  in  the  stem,  coincides  with  the  surface  of  the 
water.     The  coin  is  then  to  be  transferred  to  the  lower  scale, 
and  as  much  weight  added  to  the  upper  one  as  compensates 
this  change.     This  weight  is  obviously  just  equivalent  to  the 
resistance  which  the  coin  encounters  in  sinking  in  the  water. 
Let  this  weight  be  called  A. 

597.  In  the  next  place,  the  body  is  to  be  removed  from  the 
gravimeter,  and  as  much  weight,  B,  again  added  to  the  upper 
scale,  as  will  cause  the  mark  upon  the  stem  to  coincide  with 
the  aqueous  surface.    Of  the  weight  first  employed,  no  account 
need  be  taken;  but  the  weight,  A,  and  the  weight  B,  used  in 
the  second  and  third  steps  of  the  process,  are  to  be  carefully 
noted,  and  added  together;  the  sum  of  A  and  B  is  then  to  be 
divided  by  A,  the  first  number  noted.     This  number,  A,  re- 
presents the  weight  of  a  bulk  of  water,  equal  in  bulk  to  the 
coin;  while  the  sum  of  the  numbers,  A  and  B  is  equivalent 
to  the  weight  of  the  coin;  since  that  aggregate  weight  has 
been  found  equivalent  to  the  weight  of  the  coin  in  sinking  the 
gravimeter. 

Method  of  finding  the  Specific  Gravity  of  a  Body  lighter  than  Water,  by  Nicholson's 

Gravimeter. 

598.  Should  the  specific  gravity  of  a  light  body,  as  a  piece  of  cork  for  instance,  be 
in  question,  place  it  on  the  upper  scale  of  the  gravimeter,  load  the  instrument,  so 
that  the  mark  on  the  stem  may  coincide  with  the  surface  of  the  water,  as  in  the  case 
above  stated,  a  leaden  disk  being  previously  laid  upon  the  lower  scale.  The  cork 
being  removed,  the  weight  requisite  to  compensate  its  absence,  gives  the  weight  of 
the  cork.  This  weight,  being  added  to  that  which  will  compensate  its  buoyancy 
when  immersed  in  water  by  being  placed  beneath  the  leaden  disk  in  the  lower  scale, 
gives  the  weight  of  a  quantity  of  water  equal  in  bulk  to  the  cork.  Hence,  if  the 
number  of  grains  representing  the  weight  of  the  cork  be  divided  by  that  representing 
the  weight  of  its  bulk  of  water,  the  quotient  will  be  the  specific  gravity,  which,  in 
this  case,  must  be  expressed  in  a  decimal  fraction,  as  it  is  less  than  unity. 


SPECIFIC  GRAVITY. 


103 


Method  of  ascertaining  the  Specific  Gravity  of  Gaseous  Substances. 

599.  Suppose  the  globe  A, 
represented  in  the  adjoining 
figure,  to  be  removed  from  the 
receiver,  R,  and  exhausted 
during  a  temporary  attach- 
ment to  an  air-pump,  by  means 
of  a  screw  with  which  the 
globe  is  furnished,  and  which 
serves  also  to  fasten  it  to  the 
receiver,  as  represented  in  the 
figure.  Being  preserved  in 
this  state  of  exhaustion  by 
closing  the  cock,  let  it  be  sus- 
pended from  a  scale  beam,  and 
accurately  counterpoised,  as  in 
a  former  experiment.  (71 ,  &c.) 
In  that  experiment,  after  the 
globe  was  counterpoised,  air 
was  admitted  and  caused  it  to 
preponderate  decidedly.  If  in 
lieu  of  admitting  air,  the  globe 
be  restored  to  the  situation  in 
which  it  appears  in  this  figure, 
so  as  to  be  filled  with  hydro- 
gen from  the  receiver,  R,  and 
afterwards  once  more  sus- 
pended from  the  beam,  instead 
of  preponderating  decidedly 
as  when  air  was  allowed  to 
enter,  the  additional  weight  ac- 
quired by  it  in  consequence  of 
the  admission  of  the  hydro- 
gen, will  scarcely  be  rendered 
perceptible.  Supposing,  how- 
ever, that  the  additional  weight 

thus  acquired  were  detected,  and  also  the  weight  gained  by  the  admission  of 
exactly  the  same  bulk  of  atmospheric  air,  after  a  similar  exhaustion  of  the 
globe,  the  weights  of  equal  volumes  of  hydrogen  and  air  would  be  repre- 
sented by  the  weights  thus  ascertained.  The  specific  gravity  of  atmosphe- 
ric air  is  the  unit,  in  multiples  or  fractions  of  which  the  specific  gravities  of 
the  gases  are  expressed.  Hence  the  weight  of  a  given  bulk  of  hydrogen, 
divided  by  the  weight  of  an  equal  bulk  of  air,  gives  the  specific  gravity  of 
hydrogen.  By  a  similar  process,  the  specific  gravity  of  any  other  gas  may 
be  ascertained. 


Of  the  Influence  of  the  Air  on  the  apparent  Weight  of  Bodies. 

GOO.  A  pleasant  illustration  of  the  loss  of  weight,  and  consequent  inaccuracy  at- 
tendant  on  the  ordinary  process  of  weighing,  as  conducted  in  the  air,  is  afforded  by 
the  apparatus  and  process  described  in  the  next  page.  (001,  &c.) 


104 


PONDERABLE  MATTER. 


A  Pound  of  Feathers  heavier  than  a  Pound  of  Lead. 

601.  If  two  bodies,  one  of  which  is  more  bulky 
than  the  other,  be  found  equiponderant  in  the  or- 
dinary  process   of  weighing   by   a   balance,  the 
larger  body  is  the  heavier. 

602.  Let  the  bodies  in  question  be  those  repre- 
sented within  the  receiver  of  an  air-pump,  in  the 
annexed    figure.     On    withdrawing    the    air   by 
means  of  the   pump,  it  will   be  found   that  the 
larger    body    preponderates,     though    previously 
counterpoised  with  accuracy. 

603.  Rationale. — It  appears  from  a  preceding  illus- 
tration, (573,  &c .)  that,  when  any  body  is  surround- 
ed by  a  fluid,  it  is  buoyed  up  with  a  force  in  propor- 
tion to  the  weight  of  the  fluid,  and  the  quantity 
displaced  by  the  body.    Of  course,  the  more  space 
it  occupies  in  proportion  to  its  weight,  the  more 
will  its  weight  be  counteracted.     In  the  case  of 
the  two  bodies  rendered  equiponderant  in  air,  the 
weight  of  the  larger  is  most  counteracted  by  the 
air.     Hence,  on  exhausting  the  air  from  the  re- 
ceiver, the  larger  body  shows  a  preponderancy 
over  the  other,  equivalent  to  the  superior  support 
which  the  air  had  afforded  it. 

604.  A  similar  result  may  be  obtained,  if  hydro- 
gen be  substituted  in  the  receiver  for  atmospheric 
air;  because,  as  its  specific  gravity  to  that  of  the 
air  is  only  as  1  to  14  nearly,  each  body  would  lose 
13-14ths  of  the  support  which  the  air  had  afforded ; 

but  the  larger  body,  having  received  more,  would  lose  more.  It  follows,  that  the 
common  saying,  that  "  a  pound  of  feathers  is  as  heavy  as  a  pound  of  lead,"  falls 
short  of  the  truth;  as  they  would  really  prove  heavier  were  the  air  removed. 


Table  of  the  Specific  Gravities  of  the  Principal  Permanent  Gases :  also  of  the  Weight 
of  100  Cubic  Inches  of  each  Gas. 

605.  This  table  is  inserted  here  for  convenient  reference,  not  as  an  object  of  study 
collectively. 


Air 

Oxygen 

Chlorine 

Protoxide  of  chlorine 

Hydrogen 

Steam 

Chlorohydric  (muriatic)  acid 

Nitrogen     - 

Nitrous  oxide 

Nitric  oxide 

Ammonia 

Sulphurous  acid     - 

Sulphydric  acid  (sulphuretted  hydrogen) 

Carbonic  oxide 

Carbonic  acid          - 

Carburetted  hydrogen  (light) 

Olefiant  gas 

Cyanogen 

Chloroxycarbonic  acid 

Fluosilicic  acid 

Fluoboric  acid 


Specific 
gravity  at 
60  degrees. 

Weight  of 
100  cubic 
inches   in 
grains. 

1 

30.5 

1.1111 

33.8888 

2.5 

76.25 

2.4444 

74.5555 

0.0694 

2.1180 

0.625 

19.0620 

1.28472 

39.1839 

0.9722 

29.6527 

1.5277 

46.5972 

1.04166 

31.7708 

0.59027 

18.0035 

2.2222 

67.7777 

1.1805 

36.0069 

0.9722 

29.6527 

1.5277 

46.5972 

0.5555 

16.9444 

0.9722 

29.6527 

1.8055 

55.0694 

3.4722 

105.9020 

3.6111 

110.1385 

2.3622 

72.0471 

(Page  105.) 


MODE  OF  COLLECTING  AND  PRESERVING  GASES.     105 


SECTION  IV. 

DEFINITION  AND  DISCOVERY  OF  THE  AERIFORM  FLUIDS 
CALLED  GASES. 

606.  It  appears  from  the  phenomena  of  calorific  repulsion, 
that  solid  ponderable  matter,  by  combining  with  caloric, 
first  expands,  next  melts,  and  finally  passes  into  that  elas- 
tic state  of  fluidity,  in  which  the  repulsive  power  so  far 
predominates  over  the  attractive,  that  the  particles  recede 
from  each  other  as  far  as  external  pressure  will  permit. 
When  a  substance  is  naturally  aeriform,  it  is  called  a  gas: 
when  it  retains  the  form  of  air  only,  in  consequence  of  ex- 
traordinary (238,)  heat,  or  a  removal  of  pressure,  it  is 
called  a  vapour. 

607.  All  gases  were  considered  as  common  air,  variously 
modified  by  impurities,  until  Dr.  Black  ascertained  the  na- 
ture of  carbonic  acid  gas.     Incited  by  this  discovery,  oxy- 
gen, nitrogen,  hydrogen,  chlorine,  and  many  other  sub- 
stances susceptible  of  the  gaseous  state,  were  discovered, 
or  distinguished,  by   Scheele,   Priestley,  Cavendish,  and 
others. 

Of  the  Art  of  Collecting  and  Preserving  the  Gases. 

608.  Cisterns  filled  with  water  or  mercury,  called  hydro-pneumatic  or 
mer curio-pneumatic  according  to  the  liquid  employed,  are  used  for  collect- 
ing gases.     The  vessels  intended  to  contain  the  gas  are  filled  with  water  or 
mercury,  and  placed,  in  an  inverted  position,  on  a  shelf,  or  part  of  the  cis- 
tern, situated  just  below  the  surface  of  the  liquid.     As  their  orifices  are  not 
raised  above  the  surface,  they  remain  full  of  the  liquid,  in  consequence  of 
the  pressure  of  the  atmosphere.  (86,  87,  132.)     Any  gas  emitted  under  the 
mouth  of  a  vessel,  so  filled  and  situated,  rises  to  the  top  and  displaces  the 
contained  liquid. 

Hydro-pneumatic  Cistern. 

609.  In  the  Appendix  will  be  found  an  engraving  and  description  of  a  hydro-pneu- 
matic cistern,  which  I  employed  in  the  experimental  illustrations  of  my  lectures  for 
more  than  ten  years;  and  which  I  should  probably  continue  to  use  now,  had  not  the 
command  of  water  from  the  public  works,  put  it  into  my  power  to  dispense  with  the 
mechanism  for  keeping  the  water  at  a  proper  level.     As  I  am  now  situated,  any  de- 
ficit of  water  is  easily  supplied  from  the  pipes  known  here  as  the  hydrant  pipes,  by 
which  the  city  is  supplied  with  water;  and  any  excess  is  carried  off  by  a  waste  pipe. 

610  A  A,  (see  opposite  engraving)  is  a  water-tight  platform,  surrounded  by  a  wood- 
en rim,  R  R  R  R,  rising  above  it  about  an  inch  and  a  half.  B,  C,  T,  are  three  wells 
or  cavities,  each  in  the  form  of  a  hollow  parallelepiped,  with  all  of  which  the  cavity 
bounded  by  the  rim  communicates;  so  that  when  supplied  with  water  to  the  level  of 
the  waste  pipe,  this  liquid  fills  the  wells,  and  covers  the  platform  to  the  depth  of 
about  fths  of  an  inch. 

611.  E,  F,  G,  are  shelves,  which  severally  move  in  grooves  over  the  wells,  so  that 
they  may  be  placed  in  the  most  convenient  position.  Under  H  is  a  waste  pipe.  At 
14 


106 


PONDERABLE  MATTER. 


I,  is  a  winch  which  serves  to  let  in  water  from  the  public  reservoirs.  K,  is  a  pipe 
for  emptying  the  wells  and  casks,  with  all  of  which,  by  means  of  cocks,  it  may  be 
made  to  communicate  when  requisite.  N,  is  a  cask  which  acts  as  a  gas-holder,  hav- 
ing a  communication  with  the  cistern  for  letting  in  water  from  that  source  ;  the  ori- 
fices being  controlled  by  valves.  By  means  of  a  pipe  proceeding  from  its  vertex,  the 
gas-holder  communicates  with  a  pipe  or  cock,  at  s,  furnished  with  a  gallows  screw. 
To  this,  flexible  leaden  pipes  may  be  attached,  for  transferring  gas  either  from  the 
gas-holder  to  a  bell  glass,  or  from  a  bell  glass  to  the  gas-holder.  When  a  communi- 
cation is  established  between  the  cavities,  either  of  these  offices  may  be  performed, 
accordingly  as  the  pressure  within  the  holder  is  made  greater  or  less  than  that  of  the 
atmosphere.  It  will  be  greater  when  the  valve  for  the  admission  of  water  is  opened, 
that  for  letting  it  out  being  shut;  and  less  when  these  circumstances  are  reversed. 

612.  Another  cask  with  pipes  and  cocks,  similar  to  that  represented  in  the  engrav- 
ing, is  concealed  by  the  pannel,  O. 

613.  This  cut  affords  a  view  of  the  lower  side  of  the 
sliding  shelf,  in  the  wood  of  which  will  be  seen  two 
excavations,  T,  T,  converging  into  two  holes.  This 
shelf  is  loaded  with  an  ingot  of  lead  at  L,  to  prevent 
it  from  floating  in  the  water  of  the  cistern. 


Mercurio-pncumatic  Cistern. 

614.  The  following  figure  represents  the  mercurial  cistern  used  in  my  laboratory. 
The  front  is  supposed  to  be  removed,  that  the  inside  may  be  exposed  to  view. 


IB 


615.  B  B,  is  a  wooden  box,  which  encloses  the  reservoir  so  as  to  catch  any  of  the 
metal  which  may  be  propelled  over  the  margin  of  the  cistern.  This  box  is  bottomed 
upon  stout  pieces  of  scantling,  tenanted  together  and  grooved  so  as  to  conduct  the 
mercury  towards  one  corner,  where  there  is  a  spout  to  convey  it  into  a  vessel,  situ- 
ated so  as  to  receive  it.  The  cistern  itself  is  made  out  of  a  solid  block  of  white 
marble.  It  is  27  inches  long,  24  wide,  and  10  deep. 

616  The  ledges,  S  S,  answer  for  the  same  purposes  as  the  shelves  in  the  hydro- 
pneumatic  cistern  described  in  the  preceding  article.  The  excavation,  w,  constitutes 
the  well.  In  this  well  vessels  are  filled  with  mercury,  in  order  to  be  inverted  and 
placed  while  full  on  the  ledges.  There  are  some  round  holes  in  the'marble  for  in- 
troducing upright  wires  to  hold  tubes  or  eudiometers ;  also  some  oblong  mortices  for 
allowing  the  ends  of  tubes,  duly  recurved,  to  be  introduced  under  the  edges  of  ves- 
sels to  be  filled  with  gas,  and  in  cases  of  rapid  absorption,  to  afford  a  passage  for  the 
mercury  into  vessels,  into  which  its  entrance  might  be  impeded,  in  consequence  of 
their  close  contact  with  the  marble  of  the  reservoir.  To  fill  this  reservoir  requires 
nearly  600  pounds  of  mercury. 

Large  Gasometer  for  Oxygen. 

617.  The  opposite  engraving  represents  a  section  of  my  gasometer  for  oxygen  or 
other  gases,  which  is  capable  of  holding  between  eight  and  nine  cubic  feet  of  gas. 
It  is  represented  as  it  was  situated,  when  the  drawing  was  made,  in  the  cellar  under 
my  lecture  room.  It  is  now  placed  in  the  lecture  room  in  front  of  my  table,  near 
one  end.  The  wooden  tub,  V,  is  necessarily  kept  nearly  full  of  water.  The  cylin- 
drical vessel,  T,  of  tinned  iron,  is  inverted  in  the  tub,  and  suspended  and  counter- 
poised by  the  rope  and  weight,  in  such  manner  as  to  receive  any  gas  which  may 
proceed  from  the  orifice  of  the  pipe  in  its  axis.  This  pipe,  passing  by  means  of  a 
water-tight  juncture  through  the  bottom  of  the  tub,  is  extended  to  a  cock  fixed  in  a 


Large  Gasometer  for  Oxygen. 


(Page  100.) 


OF  SIMPLE  PONDERABLE  ELEMENTS.  107 

cavity  made  in  the  plank  forming  the  rim  of  the  pneumatic  cistern.  Hence  by 
means  of  this  cock,  and  a  leaden  pipe  soldered  to  a  brass  knob,  properly  perforated, 
a  communication  may  be  established  between  the  cavity  of  the  gasometer  and  any 
other  vessel,  for  the  purpose  either  of  introducing  or  withdrawing  gas.  In  filling 
this  gasometer,  the  copper  vessel  and  bell  glass,  used  in  obtaining  nitrous  oxide,  may 
be  employed  advantageously;  -or  the  counter-weight  being  made  heavier  than  the 
vessel  by  appending  additional  weight  to  the  rincr,  K,  the  gas  may  be  sucked  in 
from  a  bell  glass,  situated  over  the  pneumatic  cistern,  as  fast  as  it  enters  the  bell 
from  the  generating  apparatus. 

CIS.  As  the  gas  displaces  the  water  from  the  cavity  of  the  vessel,  T,  the  latter 
becomes  more  buoyant,  and  consequently  rises.  When  any  gas  is  withdrawn  or 
expelled,  the  water  resumes  its  place,  and  the  vessel  sinks. 

G19.  Gasometers  which  contain  40  or  50,000  cubic  feet  have  been  ponstructed  upon 
this  principle  for  holding  the  gas  from  oil  or  coal.  They  are  usually  hollow  parallel- 
epipeds. The  upper  vessel  is  generally  made  of  varnished  sheet  iron,  the  lower  one 
of  brick-work  or  cast  iron.  The  space  within  the  lower  vessel,  which  is  included 
by  the  upper  one  when  down,  is  filled  up,  so  as  to  lessen  the  quantity  of  water  re- 
quired. (See  article  on  carburetted  hydrogen.) 


INORGANIC  CHEMISTRY, 

OR  CHEMISTRY  OF  INORGANIC  SUBSTANCES. 

OF  SIMPLE  PONDERABLE  ELEMENTS,  THEIR  REACTIONS  WITH 
EACH  OTHER,  AND  THE  RESULTING  COMBINATIONS. 

620.  Having  in  the  preceding  pages  treated  of  certain  general  properties 
of  ponderable  matter,  or  those  means  of  ascertaining  or  observing  them  of 
which  a  knowledge  is  indispensable  to  a  chemist,  I  shall,  in  the  next  place, 
proceed  to  the  consideration  of  ponderable  substances  individually,  and  their 
reactions  and  combinations  with  each  other. 

621.  In  treating  of  ponderable  elements  and  their  multifarious  compounds, 
various  arrangements  have  been  pursued  by  different  writers.     Some  have 
preferred  to  begin  with  elements,  and  to  proceed  to  compounds;  others  to  begin 
with  compounds,  and  to  proceed  to  elements.     In  favour  of  the  last  men- 
tioned course,  it  may  be  alleged,  that  the  most  interesting  substances  in  nature 
become  known  to  us  at  first,  in  a  state  of  combination.     Thus,  for  instance, 
the  air,  water,  salts,  acids,  alkalies,  also  flesh,  sugar,  farina,  and  other  or- 
ganic products,  valuable  either  as  food  or  as  medicine,  are  compounds  which 
have  been  naturally  made  the  subjects  of  chemical  inquiry ;  and  it  may  be 
inferred  that  the  student  might  with  advantage  be  induced  to  travel  in  those 
paths,  of  which  a  successful  pursuit  has  led  to  that  chemical  knowledge 
which  it  is  the  object  to  impart.     In  this  way  he  proceeds  from  facts  which 
he  knows,  to  such  as  he  ought  to  learn,  in  the  order  in  which  he  would 
spontaneously  advance  as  far  as  he  might  be  competent.     But  it  may  be 
objected,  that  no  sooner  are  the  ingredients  of  a  body  stated,  than  the  stu- 
dent is  distracted  by  names,  of  which  he  is  ignorant;  and  which  there  is  an 
immediate  necessity  to  explain.     Hence  it  follows  that  the  ingredients  of  a 
compound  may  come  to  be  considered  in  immediate  succession,  when  they 
may  have  no  analogy  with  each  other;  while  it  is  highly  advantageous, 
after  having  treated  of  any  one  element,  to  proceed  to  that  which  has  the 
greatest  analogy  with  it.     In  that  case,  a  certain  portion  of  the  conceptions 
which  have  been  formed  respecting  one  element,  may  be  extended  to  ano- 
ther, with  little  mental  exertion,  and  without  much  additional  pressure  upou 
the  memory. 


108  INORGANIC  CHEMISTRY. 

622.  The  method  first  mentioned  of  treating  of  each  elementary  sub- 
stance first,  and  afterwards  of  compounds,  is  objectionable,  because  it  cannot 
be  put  into  practice  effectually.     To  treat  of  the  chemical  habitudes  of  any 
one  element,  requires  that  we  should  speak  of  other  elements,  in  reacting 
with  which,  those  habitudes  are  displayed,  and  respecting  which  a  beginner 
is  of  course  ignorant.     In  pursuing  this  course,  each  substance  must  be 
treated  of  imperfectly,  or  language  and  illustrations  employed,  which  the 
student  is  unprepared  to  understand. 

623.  The  course  which  I  have  chosen  is  as  follows.    I  begin  with  the  ele- 
ment which,  of  all  ponderable  matter,  has  the  most  important  part  assigned 
to  it  in  nature ;  I  mean  oxygen.     The  history,  state  of  existence  in  nature, 
means  of  procuring,  and  properties  of  this  substance,  so  far  as  they  can  be 
rendered  intelligible  to  a  novice,  are  stated,  or  exemplified  and  explained. 
In  the  next  place  to  oxygen,  I  present  chlorine  to  attention,  which  has  at 
least  as  much  analogy  with  oxygen,  as  any  other  known  element,  and  is, 
at  the  same  time,  an  agent  of  high  importance.     Having  treated  separately 
of  oxygen  and  chlorine,  as  far  as  may  be  expedient,  the  compounds  which 
they  form  with  each  other,  may,  in  the  next  place,  to  a  certain  extent,  be 
treated  of  with  advantage.     Then,  guided  by  analogy,  bromine  and  iodine, 
though  inferior  in  importance,  may  be  successively  treated  of,  and  subse- 
quently all  the  compounds  which  they  can  form,  either  with  oxygen  or  chlo- 
rine, or  with  each  other.     This  system  will  be  followed  in  treating  of  all 
the  elements. 

624.  Pursuant  to  this  method,  little  can  be  said  of  fluorine  in  the  section 
appropriated  to  its  consideration,  since  those  elements  with  which  its  most 
interesting  reactions  take  place,  cannot  consistently  be  made  the  object  of 
attention  under  that  section. 

625.  Cyanogen  is,  in  its  properties,  analogous  to  chlorine,  bromine, 
and  iodine,  yet  being  composed  of  carbon  and  nitrogen,  should  not  be  an 
object  of  attention,  until  the  pupil  is  prepared  by  a  knowledge  of  its  said 
constituents.     Besides,  it  comes  in  consistently  under  the  general  head  of 
carbon,  which,  agreeably  to  my  plan,  as  above  explained,  comprises  the 
compounds  of  carbon  with  all  substances  previously  treated  of,  among  which 
is  nitrogen. 

626.  Of  the  fifty-four  simple  elements  universally  recognised  by  che- 
mists, a  list,  with  their  equivalent  numbers  and  symbols,  has  already  been 
given.  (560,  &c.) 

627.  Of  these  elements,  chlorine,  bromine,  iodine  and  fluorine  are  classed 
by  Berzelius  under  the  name  of  halogen  bodies,  or  generators  of  salts ;  while 
oxygen,  sulphur,  selenium,  and  tellurium  are  classed  together  under  the 
name  of  amphigen  bodies,  or  both  producers ;  meaning  that  they  are  pro- 
ductive both  of  acids  and  bases.     To  the  elementary  halogen  bodies,  he 
adds  the  compound  body  cyanogen.     I  object  to  this  classification,  that  the 
word  salt  admits  of  no  definition,  reconcilable  with  the  use  which  has  been 
made  of  it  by  the  distinguished  author;  arid  because,  from  facts  and  defi- 
nitions practically  sanctioned  by  him,  and  chemists  in  general,  it  is  evident 
that  the  elements  belonging  to  both  of  his  classes  are  productive  of  acids 
and  bases.     Hence  I  have  associated  them  in  one  class,  under  the  appella- 
tion of  basacigen  elements*     In  honour  of  Berzelius,  I  shall,  however,  re- 
tain the  terms  halogen  and  amphigen,  in  order  to  designate  the  elements 
which  he  has  distinguished  by  those  names.     It  may  be  proper  to  add  that 
we  owe  to  Berzelius  himself  the  idea  that  any  other  substance  besides  oxy- 
gen could  form  acids  and  bases  capable  of  uniting  to  form  salts.     Our 


OF  SIMPLE  PONDERABLE  ELEMENTS.  109 

knowledge  of  the  existence  of  this  faculty  in  three  of  his  amphigen  ele- 
ments, sulphur,  selenium  and  tellurium,  is,  I  believe,  entirely  due  to  his 
investigations.  If  chemists,  myself  among  others,  who  consider  his  double 
salts  as  consisting  of  acids  and  bases,  are  in  the  right,  it  is  to  the  light  af- 
forded by  his  brilliant  discoveries  that  we  owe  the  ability  to  pursue  the  true 
path. 

628.  Before  concluding  this  preliminary  exposition  of  the  classification 
and  nomenclature  which  I  propose  to  adopt,  I  wish  to  make  it  clear,  that 
the  attribute  of  producing  both  acids  and  bases,  which,  agreeably  to  the 
plan  of  Berzelius,  is  restricted  to  his  four  amphigen  elements,  is,  agreeably 
to  mine,  extended  to  the  elements  comprised  in  both  of  his  classes,  which 
are  consequently  united  under  one  designation,  as  basacigen  elements.    My 
basacigen  class  is,  therefore,  the  amphigen  class  of  Berzelius,  enlarged 
under  a  new  and  more   descriptive  name,*  so  as  to  take  in  both  of  his 
halogen  and  amphigen  classes. 

629.  In  order  to  render  the  definition  of  a  basacigen  body  precise,  it 
may  be  necessary  that  I  should  give  a  definition  of  acidity  and  basidity.f 

630.  I  shall  proceed  to  give  a  definition  which  to  me  appears  quite 
satisfactory.     It   is   perhaps  necessary  to  premise,  that  a  tertium  quid 
was,  agreeably  to  the  old  chemists,  a  compound  in  which  the  qualities  of 
the  ingredients  were  neutralized,  or  so  much  altered,  as  to  make  a  body 
capable  of  a  chemical  reaction  differing  from  that  of  either  of  its  ingredients. 
It  means,  therefore,  a  third  something,  a  "  tertium  quid."     But  to  proceed 
to  the  definition;  it  is  as  follows. 

631.  When  of  two  compounds  capable  of  combining  together  to  form  a 
tertium  quid,  and  having  an  ingredient  common  to  both,  one  prefers  the 
positive,  the  other  the  negative  pole  of  the  voltaic  series,  we  must  deem  the 
former  an  acid,  the  latter  a  base.$ 

632.  Thus  sulphuric  acid,  (consisting  of  sulphur  in  combination  with 
oxygen,)  and  soda,  (consisting  of  sodium  and  oxygen,)  are  capable  of  com- 
bining to  form  sulphate  of  soda,  a  tertium  quid.     Each  of  these  compounds 
have  a  common  ingredient,  oxygen,  and  one  of  them,  the  acid,  prefers  the 
positive  pole  of  the  voltaic  series,  the  other  the  negative  pole.     It  follows, 
that  sulphuric  acid  is  entitled  to  the  appellation  of  an  acid,  while  soda  may 
claim  that  of  a  base. 

*  It  will,  I  trust,  be  perceived,  that  a  basacigen  element  is  one  capable  of  pro- 
ducing both  an  acid  and  a  base,  the  monosyllable  gen  being  understood,  in  chemical 
language,  when  added  to  a  word  expressive  of  a  property,  or  state,  to  signify  the 
'  power  of  producing  that  property,  or  state.  (633.) 

t  As  a  name  is  much  needed  to  convey  the  idea  of  the  basic  property,  as 
acidity  does  of  the  acid  property,  I  have  ventured,  without  any  authority,  to  em- 
ploy the  word  basidity,  which  from  its  analogy  with  acidity,  must,  I  presume,  be 
intuitively  intelligible. 

t  I  wish  it  to  be  understood,  that  I  consider  this  definition  as  only  declaratory  of 
the  practice  of  chemists,  who  all  obey  the  rule,  although,  as  far  as  I  know,  excepting 
by  myself,  it  has  never  been  enunciated. 

I  do  not  deem  it  necessary  to  introduce  into  the  text  a  corollary,  which  in- 
evitably flows  from  the  cited  definition,  as  it  would  unnecessarily  distract  atten- 
tion ;  but  it  may  be  well  before  taking  leave  of  this  subject,  to  say,  that  agreeably 
to  universal  practice,  any  body  which  is  capable  of  saturating  a  base,  is  considered 
as  an  acid ;  and  that  on  the  other  hand,  any  body  which  is  capable  of  saturating  an 
acid,  is  inferred  to  be  a  base.  It  is  upon  this  basis  that  the  pretensions  of  the  or- 
ganic alkalies  and  acids  to  be  considered  as  acids  or  bases,  are  founded. 


110  INORGANIC  CHEMISTRY. 


OF  INDIVIDUAL  PONDERABLE  ELEMENTS, 

AND  OF  THEIR  REACTION  WITH  EACH  OTHER,  AND  THE 
RESULTING  COMPOUNDS. 

633.  Classification. — Of  the  fifty-four  elements  enumerat- 
ed, (627,)  eight  being  designated  as  basacigen,  make,  with 
cyanogen,  the  compound  basacigen  body,  (629,)  nine  in  all, 
in  the  basacigen  class.  I  shall  designate  the  rest  of  the 
elements  as  radicals;  subdividing  them  into  metallic  radicals, 
and  non-metallic  radicals. 

OF  BASACIGEN  ELEMENTS. 

634.  Oxygen,  Cyanogen, 

Chlorine,  Sulphur, 

Bromine,  Selenium, 

Iodine,  Tellurium. 
Fluorine, 

They  will  be  treated  of  in  the  order  in  which  they  have 
been  named,  in  the  eight  following  sections. 

635.  I  have  already  stated  that  in  honour  of  Berzelius  I 
should  employ  his   appellations   amphigen   and  halogen. 
There  is,  in  fact,  a  necessity  for  words  to  distinguish  the 
bodies  to  which  he  has  applied  these  names;  especially 
from  the  very  great  analogy  between  those  which  are  de- 
signated as  halogen. 

636.  The  student  is  requested  to  recollect  that  chlorine, 
bromine,  iodine,  fluorine  and  cyanogen  constitute  the  ha- 
logen class  of  Berzelius,  while  oxygen,  sulphur,  selenium 
and  tellurium  form  his  amphigen  class. 

SECTION  I. 

OF    OXYGEN. 

637.  In  the  gaseous  state,  oxygen  forms  one-fifth  of  the 
atmosphere  in  bulk ;  and  as  a  constituent  of  water  in  the 
ratio  of  eight  parts  in  nine,  it  pervades  every  part  of  the 
creation  where  that  important  compound  is  to  be  found. 
It  exists  in  that  congeries  of  oxidized  matter  which  we 
call  earth,  and  is  a  principal  and  universal  constituent  of 


OXYGEN.  Ill 

animal  and  vegetable  matter.  Its  combinations  with  me- 
tals and  various  other  combustibles  are  of  the  highest 
importance  in  the  arts.  It  was  called  oxygen  under  the 
erroneous  impression  of  its  being  the  sole  acidifying  prin- 
ciple, from  the  Greek  ofa  acid,  and  y<v«^<  to  generate. 

638.  Preparation. — It  can  only  be  isolated  in  the  form 
of  a  gas.     It  is  yielded  by  red  lead,  nitre,  or  black  oxide 
of  manganese,  when  exposed  to  a  bright  red  heat  in  an 
iron  bottle.     There  are  various  other  means  of  obtaining 
oxygen  gas.     It  is N  generally  supposed  that,  in  order  to 
obtain  it  in  a  high  degree  of  purity,  chlorate  of  potash 
must  be  employed ;  but  I  have  found  the  first  portions  of 
the  gas  as  evolved  by  a  red  heat  from  nitrate  of  potash  or 
nitrate  of  soda  very  nearly  pure ;  and  Dr.  Thomson  al- 
leges that  this  salt,  by  exposure  to  a  carefully  regulated 
heat,  parts  with  one-fifth  of  the  oxygen  of  its  acid  in  a 
state  of  purity ;  or  in  other  words,  it  gives  up  an  atom  of 
oxygen  for  every  atom  of  the  salt,  which  is  equal  to  8 
parts  in  102  parts,  or  rather  more  than  one-thirteenth. 

639.  Properties  of  Oxygen* — The  specific  gravity  of  this 
gas,  atmospheric  air  being  1.,  is  1.1024.     One  hundred  cu- 
bic inches  of  it  weigh  34.1872  grains.     In  refracting  light, 
oxygen  is  inferior  in  power  to  any  of  the  other  gases. 

640.  It  is  insipid,  inodorous,  colourless,  and  transparent. 
It  is  but  slightly  absorbed  by  water,  does  not  differ  from 
common  air  in  appearance,  but  is  somewhat  heavier,  and 
supports  life  and  combustion  more  actively.     Under  a  bell 
glass  filled  with  oxygen  gas,  an  animal  lives,  or  a  candle 
burns,  thrice  as  long,  as  when  similarly  situated  with  the 
same  quantity  of  common  air.     Oxygen  gas  is  supposed 
to  consist  of  oxygen  rendered  aeriform  by  caloric.     The 
equivalent  of  oxygen  is  8,  hydrogen  being  unity. 

Apparatus  for  obtaining  Oxygen  upon  a  large  Scale. 

641.  As  nearly  as  much  time  and  trouble  are  expended  in  conducting  a  chemical 
process  on  a  small  scale  as  upon  a  large  one ;  and  as  in  my  experiments  I  consume 
large  quantities  of  oxygen  gas,  I  have  lately  employed  the  cast  iron  alembic  repre- 
sented in  the  following  figure,  for  the  purpose  of  obtaining  the  gas  from  12  or  15 
pounds  of  nitre.     When  in  operation,  it  is  made  to  occupy  a  suitable  cavity  in  a 
brick  stack,     The  neck  is  so  formed  as  to  receive  a  large  hollow  knob  of  iron,  from 
which  a   gun  barrel  proceeds  at  right  angles.     This  knob  is  secured  by  a  gallows 
screw,  embracing  the  arms  cast  with  the  alembic.     The  juncture  is  to  be  luted  with 
clay,  added  dry  to  a  saturated  solution  of  borax.     To  the  orifice  of  the  gun  barrel, 
a  flexible  leaden  pipe  is  attached,  by  which  the  gas  is  conveyed  to  the  gas-holders 
or  gasometer. 

642.  Care  is  taken  to  use  no  more  fire  than  will  bring  over  the  gas,  and  the  opera- 
tion is  arrested  as  soon  as  the  impurity  exceeds  20  per  cent.    By  attending  to  these 


112  INORGANIC  CHEMISTRY, 


precautions,  the  gas  is  of  better  quality ;  the  first  portion  being  nearly  pure,  and  the 
alembic  is  less  corroded.  Besides,  the  nitrate,  being  converted  into  nitrite  of  potash, 
produces,  by  deflagration  with  charcoal,  a  tolerably  pure  carbonate  of  potash. 

Experimental  Illustrations  of  the  Properties  of  Oxygen  Gas. 

643.  Several  cylindrical  glass  vessels  of  an  appropriate 
shape  being  filled  with  the  gas  over  one  of  the  shelves  of 
the  pneumatic  apparatus,  the  following  illustrations  of  the 
energy  of  oxygen  gas  in   supporting  combustion  are  af- 
forded. 

644.  Let  a  stout  wire  be  made,  at  one  of  its  ends,  to  em- 
brace a  lighted  candle,  so  that  it  may  be  conveniently 
lowered  into  the  bell  while  replete  with  oxygen.     It  will 
be  found  that,  if  the  flame  be  extinguished,  and  the  candle 
lowered  into  the  gas  while  the  snuff  remains  red-hot,  the 
inflammation  will  be  renewed  with  great  energy. 

645.  The  vessel  being  replenished  with  gas,  the  flame  of 
a  piece  of  burning  caoutchouc,  let  down  into  it,  acquires  a 
dazzling  brightness. 

646.  Let  Homberg's  pyrophorus,  or  preferably  such  as  I 
have  contrived  to  obtain  from  Prussian  blue,  or  tanno  gal- 
late  of  iron  fall  through  the  gas.     During  its  descent  the 
pyrophorus  takes  fire  spontaneously,  producing  an  igneous 
shower. 


OXYGEN. 


113 


647.  An  analogous  fiery  shower  results,  when  charcoal 
powder,  or  filings  of  iron  or  steel,  made  red-hot  in  a  cruci- 
ble, are  projected  in  like  manner  into  oxygen. 

648.  If  (by  means  of  a  blowpipe,)  a  jet  of  oxygen  be 
made  to  act  upon  a  lamp  flame,  or  upon  that  of  hydrogen, 
whether  pure  or  carburetted,  an  intense  heat  will  be  ex- 
cited. (379.) 

649.  An  iron  wire,  being  heated  in  the  flame  thus  ex- 
cited by  oxygen,  takes  fire,  and  continues  to  burn  splen- 
didly, although  the  lamp  be  removed. 

Combustion  of  Iron  or  Steel  in  Oxygen. 

C50.  Place  over  the  orifice  of  a 
pipe  communicating  with  a  cock  of 
one  of  the  air  holders  supplied  with 
oxygen,  a  glass  vessel,  such  as  is 
usually  employed  to  shelter  candles 
from  currents  of  air.  Let  the  upper 
opening  of  the  vessel  be  closed  by  a 
lid  with  a  central  circular  aperture, 
as  represented  in  the  engraving. 
Leaving  this  aperture  open,  by  turn- 
ing the  key  of  the  cock,  allow  the 
gas  to  rise  into  the  vessel,  from  the 
holder. '  Next  apply  a  taper  to  the 
aperture,  and  as  soon  as  it  indicates, 
by  an  increased  brilliancy  of  com- 
bustion, that  oxygen  has  taken  the 
place  of  the  air  previously  in  the 
vessel,  cover  the  aperture.  In  the 
next  place,  attach  a  small  piece  of 
spunk  to  one  end  of  a  watch  spring, 
or  of  a  spiral  wire  as  in  the  figure. 
Ignite  the  spunk,  and  removing  the 
cover,  plunge  the  end  of  the  spring 
associated  with  the  spunk  into  the 
gas.  The  access  of  the  oxygen 
causes  the  spunk  to  be  ignited  so 
vividly,  that  the  spring  or  wire, 
takes  fire  and  burns  with  great 
splendour,  forming  a  brilliant  liquid 
globule,  which  scintillates  beauti- 
fully. This  globule  is  so  intensely 
hot,  that  sometimes,  on  falling,  it 
cannot  immediately  sink  into  the  water,  but  leaps  about  on  the  surface,  in  conse- 
quence of  the  steam  which  it  causes  the  water  to  emit.  If  it  be  thrown  against  the 
glass  of  the  containing  vessel,  it  usually  fuses  it  without  causing  a  fracture,  and  has 
been  known  to  pass  through  the  glass,  producing  a  perforation  without  any  other 
injury.  These  phenomena  are  more  likely  to  be  produced  when  an  iron  wire  is 
used  in  this  experiment,  than  when  a  steel  spring  is  employed,  as  the  fusing  point  of 
malleable  iron  is  higher  than  that  of  steel. 

Necessity  of  Oxygen  to  a  Candle  Flame  dnnonstratnl. 

C51.  A  candle  will  l.urn  only  for  a  limited  time  in  a  limited  supply  of  air;  it  will 
not  burn  in  vacuo,  but  burns  brilliantly  in  oxygen  gas,  and  much  longer  than  in  a 
like  quantity  of  air. 
15 


114 


INORGANIC  CHEMISTRY 


652.  Let  there  be  two  bell  glasses,  A  and  B,  communicating  with  each  other  by  a 
flexible  leaden  pipe,  a  cock  intervening  at  C.  Suppose  A  to  be  placed  over  a  lighted 
candle  on  the  plate,  D,  which  communicates  with  an  air  pump  plate  as  represented 
at  E.  It  will  be  found  that  the  candle  will  gradually  burn  more  dimly,  and  will  at 
last  go  out,  if  no  supply  of  fresh  air  be  allowed  to  enter  the  containing  bell.  If  on 
repeating  the  experiment,  the  air  be  withdrawn  by  means  of  the  pump,  the  candle  is 
rapidly  extinguished.  It  is  thus  demonstrated  that  a  candle  will  not  burn  in  vacuo, 
and  that  it  can  burn  only  for  a  limited  time,  in  a  limited  portion  of  atmospheric  air. 

653  If,  while  the  bell,  A,  is  exhausted,  the  cock  at  C  be  opened,  communicating 
with  the  receiver,  B,  filled  with  oxygen  over  the  pneumatic  cistern,  the  water  will 
rise  into  and  fill  the  receiver,  while  the  gas  will  be  transferred  to  the  bell.  By 
means  of  the  galvano-ignition  apparatus  (335),  the  candle  may  be  again  lighted  in 
the  oxygen,  when  it  will  burn  splendidly. 

Combustion  of  Phosphorus  in  Oxygen  Gas. 


B 


G54.  A  brass  plate,  which  answers  as  an  extra  air  pump  plate,  is  supported  on  a 
hollow  cylinder  of  the  same  metal.     Concentric  with  the  axis  of  this  cylinder,  and 


OXYGEN. 


115 


passing  up  through  it,  so  as  to  reach  about  three  inches  above  the  plate,  there  is  a 
tube  of  about  three-fourths  of  an  inch  in  diameter,  open  below,  but  closed  above  by 
a  concave  copper  disk  to  which  it  is  hard  soldered.  The  tube  is  fastened  into  the 
cylinder  by  a  brass  screw  plug,  in  the  centre  of  which  the  tube  is  soldered.  Hence, 
although  the  bore  of  the  tube  is  accessible  from  below,  so  far  up  as  the  concave  cop- 
per disk  which  surmounts  it,  no  air  can  pass  through  it,  or  through  the  cylinder. 

<)•">•">.  About  twenty  grains  of  phosphorus  being  placed  upon  the  copper  disk,  a 
glass  globe  is  put  over  it  upon  the  plate  ;  and  by  causing  one  of  the  pipes  which  are 
attached  laterally  to  the  cylinder  to  communicate  with  an  air  pump  in  operation,  the 
globe  is  exhausted.  By  means  of  the  other  pipe,  a  due  quantity  of  oxygen  gas  is 
then  let  in  from  the  bell  glass,  B,  to  which  this  pipe  is  annexed.  The  apparatus 
being  thus  prepared,  the  end  of  an  iron  rod  previously  reddened  in  the  fire,  is  passed 
through  the  bore  of  the  tube  so  as  to  touch  the  copper  disk  which  holds  the  phos- 
phorus. The  most  vivid  ignition  ensues.  The  light  has  at  first  a  dazzling  beauty, 
but  is  soon  "  shorn  of  its  beams"  by  the  dense  white  fumes  of  phosphoric  acid,  which 
the  combustion  evolves-  Hence,  an  effulgence,  approaching  to  solar  brilliancy,  soon 
yields  to  a  milder  illumination  like  that  of  the  moon,  rendered  more  pleasing  by  the 
contrast. 

656.  The  globes  with  which  I  am  accustomed  to  perform  this  experiment  contain 
about  15  gallons.     It  is  better  that  the  gas  in  the  globe  should  be  in  some  degree 
rarefied;  otherwise  the  expansion  at  first  excites  a  considerable  effort  in  the  air  to 
escape.     The  enlargement  of  bulk,  arising  from  the  heat,  may  be  provided  for  by  a 
bag  or  bladder,  a  communication  with  which  being  opened,  a  portion  of  the  heated 
gas  is  enabled  to  retire,  till  the  condensation  of  the  oxygen  with  the  phosphorus, 
into  phosphoric  acid,  compensates  the  expansion. 

657.  I  have  performed  this  experiment,  when  the  density  of  the  gas  was  one-half 
less  than  if  in  equilibrio  with  the  atmospheric  pressure.     This  of  course  obviated  the 
possibility  of  any  ill  consequences  from  expansion. 

Combustion  of  Sulphur  in  Oxygen  Gas. 


R 


116  INORGANIC  CHEMISTRY. 

658.  Supposing  the  junctures  made  by  the  plates,  P  />,  with  the  receiver,  R,  to  be 
air-tight,  and  that  there  is  a  communication  between  it  and  the  bell  glass,  B,  by 
means  of  a  flexible  leaden  pipe,  L,  it  must  follow  that,  whenever  the  suction  pump, 
from  which  the  recurved  pipe,  S,  terminating  within  the  bell,  proceeds,  is  made  to 
act,  the  air  in  B  being  rarefied,  that  in  R  will  force  its  way  through  L,  and  the  liquid 
in  the  vase  upon  the  stand.     It  must  also  be  evident  that,  if  the  pipe  and  cock,  C, 
communicate,  on  one  side  with  the  receiver,  on  the  other  with  a  reservoir  of  oxygen, 
this  gas  will  be  impelled  into  the  receiver,  as  soon  as  the  cock  is  opened,  in  order  to 
restore  the  equilibrium  destroyed  by  the  suction  pump. 

659.  The  plate,  P,  with  its  supporting  hollow  brass  cylinder,  has  been  already  de- 
scribed in  the  preceding  article.     The  tube,  surmounted  by  the  disk,  used  in  the 
combustion  of  phosphorus,  is  removed,  and  in  its  place  a  piece  of  a  gun  barrel  is,  in 
like  manner,  fastened,  so  that  the  butt-end  may  occupy  the  axis  of  the  cylinder. 
The  touch-hole  being  closed,  a  perforation,  similar  in  size,  is  drilled  in  the  end  of 
the  barrel,  at  the  point  from  which  the  flame  is  represented  as  proceeding  in  the 
figure.     In  order  to  produce  this  jet  of  vaporized  sulphur,  some  cotton  wick  is  wound 
about  the  end  of  a  rod,  and  tied  on  it.     The  tuft,  thus  made,  is  soaked  in  melted 
brimstone.     The  gun  barrel,  during  a  temporary  removal,  is  heated  red-hot  at  the 
butt-end,  where  it  is  perforated.     Being  screwed  into  its  place  again,  the  rod,  armed 
with  the  cotton  and  sulphur,  is  pushed  up  into  the  bore  of  the  barrel.     By  the  heat 
of  the  iron,  the  sulphur  is  converted  into  a  hot  vapour,  which,  issuing  in  a  jet  from 
the  perforation,  enters  into  combustion  with  the  oxygen  in  the  receiver. 

660.  In  consequence  of  the  rarefaction  of  the  air  in  the  bell,  B,  by  the  suction 
pump,  the  fumes  of  the  burning  vaporized  sulphur  are  drawn  through  the  water  in 
the  vase  upon  the  stand,  in  which,  consequently,  a  mixed  solution  oT sulphuric  and 
sulphurous  acids  is  produced. 

Additional  Illustration  of  the  Combustion  of  Sulphur 

in  Oxygen. 

661.  The  preceding  illustration  has  not  for  two  or 
three  years,  been  exhibited  before  my  class,  yet  presuming 
it  might  not  be  uninteresting  to  some  of  the  students  of 
this  work,  I  have  not  omitted  it  from  this  edition.  Lat- 
terly I  have  resorted  to  the  following  method  of  exhibiting 
the  combustion  of  sulphur  in  oxygen,  as  being  easier,  and 
yet  sufficiently  pleasing  and  instructive.  All  the  steps  of 
the  process  for  the  combustion  of  phosphorus  in  oxygen 
are  performed,  as  already  described  (651,  &c.)  but  in  lieu 
of  a  stick  of  phosphorus,  a  tuft  of  asbestos  soaked  in 
melted  sulphur,  is  placed  upon  the  capsule,  with  a  minute 
piece  of  phosphorus  beneath  it.  The  latter  when  heated 
by  the  incandescent  iron  takes  fire,  and  consequently  ig- 
nites the  sulphur,  with  which  the  asbestos  is  imbued.  In 
whiteness  and  dazzling  brilliancy,  the  light  afforded  by  the 
combustion  of  sulphur  in  oxygen  is  inferior  to  that  evolved 
by  phosphorus,  when  similarly  situated;  but  this  inferiority 
is  compensated  by  the  splendour  of  its  characteristic  pur- 
ple hue. 


CHLORINE. 


117 


SECTION  II. 

OF    CHLORINE. 

662.  As  a  gas,  chlorine  exists  only  by  artificial  means; 
but  as  an  ingredient  in  marine  salt,  in  the  proportion  of 
three-fifths,  it  constitutes  nearly  one-fiftieth  of  the  matter 
in  the  ocean,  and  is  widely  disseminated  throughout  the 
land  as  well  as  the  sea.     It  is  also  an  ingredient  in  some 
of  the  most  active  agents  used  in  chemistry  or  medicine. 
It  was  discovered  by  Scheele,  and  called  by  him  dephlogis- 
ticated  marine  acid.     It  afterwards  received  the  name  of 
oxygenated  muriatic  acid,  or  oxymuriatic  acid,  from  La- 
voisier and  the  chemists  who  "adopted  his  nomenclature, 
under  the  erroneous  idea  that  it  was  composed  of  muriatic 
acid  and  oxygen.     Its  present  name  was  given  by  Sir  H. 
Davy,  from  ^A^  green,  because  its  colour  is  greenish. 

663.  Preparation. — It  is  obtained  by  heating  in  a  retort 
or  alembic,  of  glass  or  lead,  three  parts  of  black  oxide  of 
manganese,  with  four  parts  of  muriatic  acid;  or  the  same 
quantity  of  this  oxide,  with  eight  parts  of  common  salt,  four 
parts  of  sulphuric  acid,  and  four  parts  of  water. 

664.  Being  a  gas,  chlorine  must  be  received  over  the 
hydro-pneumatic  cistern  in  bell  glasses  or  bottles;  the  tem- 
perature of  the  water  should  be  raised,  by  adding  a  por- 
tion boiling  hot.     As  much  of  it  is  absorbed  if  it  remain 
long  in  contact  with  the  water,  I  generally  employ  glass 
bottles  with  air-tight  stopples,  in  order  that  they  may  be 
removed  from  the  water  as  soon  as  filled.     Berzelius  al- 
leges that  if  the  water  employed  be  saturated  with  salt, 
there  is  less  absorption. 

665.  Jars  or  bottles  may  be  filled  with  chlorine  gas,  by 
means~  of  a  tube  or  retort  beak,  as  in  fig.  1,  of  the  follow- 
ing engraving,  reaching  from  the  generating  vessel  to  the 
bottom  of  that  into  which  it  is  to  be  introduced.     The  air 
is  displaced  by  the  chlorine,  in  consequence  of  its  superior 
gravity,  without  any  admixture  ensuing  adequate  to  inter- 
fere with  the  exhibition  of  its  characteristic  properties. 

666.  When  substances  which  take  fire  in  the  gas  are  to 
be  introduced,  it  is  expedient  that  a  communication  should 
exist  with  the  inside  of  a  bladder  attached,  as  in  the  fol- 
lowing figures,  which  represent  apparatus,  of  which  fig.  1 
may  be  used  for  the  combustion  of  metallic  powders,  fig. 


118 


INORGANIC  CHEMISTRY. 


2  for  that  of  phosphorus,  introduced  by  means  of  the  la- 
dle L. 

Fig.  1. 


667.  Properties. — When  pure  and  dry,  chlorine  is  a  per- 
manent gas  of  a  greenish-yellow  colour.      Its  weight  to 
that  of  common  air,  is  nearly  as  two  and  a  half  to  one. 
Even  when  existing  in  the  air  in  very  small  proportion,  it 
is  intolerable  to  the  organs  of  respiration,  and  to  respire  it 
pure,  would  quickly  produce  fatal  consequences. 

668.  Mr.  Faraday  has  shown  that,  under  great  pressure, 
chlorine  becomes  a  liquid.     It  will  remain  liquid  some  in- 
stants after  all  pressure  is  removed,  in  consequence  of  the 
great  cold  produced  by  its  evaporation. 

669.  That  species  of  chemical  action  which  is  attended 
with  the  phenomena  of  combustion,  is  supported  by  this 
gas  with  great  energy.     It  combines  directly  with  every 
combustible  except  carbon.     It  has  a  curious  property,  first 
noticed  by  me  I  believe,  of  exciting  a  sensation  of  warmth ; 
though  a  thermometer,  immersed  in  it  at  the  same  time, 


CHLORINE. 


119 


does  not  indicate  that  its  temperature  is  greater  than  that 
of  the  adjoining  medium.  The  heat  thus  noticed  is  proba- 
bly produced  by  a  reaction  with  the  matter  insensibly  per- 
spired. 

670.  Chlorine  is  absorbed  by  water,  and  the  solution 
acts  powerfully  on  metals.     It  appears  to  be  the  only  sol- 
vent of  gold.     At  the  temperature  of  40°,  it  forms  with 
water  a  solid  hydrate,  consisting  of  1  atom  of  chlorine, 
and  10  atoms  of  water.    Silver,  in  solution,  is  the  best  test 
for  chlorine;  and,  reciprocally,  chlorine  is  the  best  test  for 
dissolved  silver.     The  compounds  of  chlorine  with  mer- 
cury, so  useful  in  medicine,  will  be  treated  of  when  on  the 
subject  of  that  metal.     When  the  aqueous  solution  of 
chlorine  is  exposed  to  the  solar  rays,  it  forms  muriatic 
acid  with  the  hydrogen  of  the  water,  while  the  oxygen 
escapes.     It  bleaches  by  liberating  the  oxygen  of  water, 
and   thus   enabling  it   to   act   on   the  colouring  matter. 
Although  it  has  no  direct  reaction  with  oxygen,  when  in 
their  nascent  state,  these  elements  unite  to  form  four  com- 
pounds, all  of  which  are  now  considered  as  acids. 

671.  About  thirty  years  ago,  chlorine  gas  was  univer- 
sally considered  as  a  compound  of  muriatic  acid  and  oxy- 
gen, and  called  oxymuriatic  acid.     It  is  now  deemed  an 
elementary  substance,  rendered  gaseous  by  caloric. 

Experimental  Illustrations  of  the  Properties  of  Chlorine. 

672.  Leaves  of  Dutch  gold,  introduced  by  means  of  a 
glass  rod  into  a  bottle  of  chlorine,  take  fire. 

673.  Calorific  influence  upon  the  fingers  compared  with 
that  upon  a  thermometer. 

674.  An  infusion  of  litmus  whitened  in  descending  in  a 
stream  through  the  gas  from  a  funnel. 

675.  A  lighted  candle  introduced,  burns  with  a  carbo- 
naceous flame. 

Combustion  of  Antimony  in  Chlorine. 

G7l5.  When  an  air  pump  is  at  hand,  the  following  apparatus  may  be  used  for  the 
)mbustion  of  powdered  antimony.     It  consists  of  a  large  ' 
supported  in  the  screw  rod  and  plate  frame  described.  (248.} 


combustion  of  powdered  antimony.     It  consists  of  a  large  jar  closed  air-tight,  and 
ipported  in  the  screw  rod  and  plate  frame  described.  (248.) 
077.  By  means  of  one  of  the  flexible  pipes  and  cocks  with  which  the  apparatus  is 


furnished,  communication  may  be  made  with  an  air  pump,  and  with  a  large  vessel, 
A  B,  containing  chlorine.  Into  the  centre  of  the  lid  a  cock  is  fastened,  the  key  of 
which,  instead  of  being  perforated  as  usual,  is  drilled  only  half  through,  so  as  to  pro- 
duce an  excavation  capable  of  holding  a  thimbleful  of  powder.  The  cavity  in  the 
key  of  the  cock  is  charged  with  pulverized  antimony,  which,  on  turning  the  key  half 
round,  falls  through  the  chlorine,  and  as  it  falls  assumes  the  appearance  of  a  shower 


120 


INORGANIC  CHEMISTRY. 


of  fire.     The  cock  being,  from  its  construction,  always  closed,  and  the  junctures 
being  tight,  the  spectators  are  protected  from  the  noxious  fumes. 


678.  In  this  experiment^the  chlorine  forms  with  the  antimony  a  compound  which 
has  less  capacity  for  caloric  and  light  than  its  ingredients  have  separately.  Hence, 
by  their  combination,  the  phenomena  of  combustion  are  produced.  The  product  of 
the  combustion  is  the  perchloride. 

Apparatus  for  the  Combustion  of  Metallic  Leaf*  in  Chlorine. 

,  679.  The  apparatus  used  in  this  experiment  (See  fig.  1,)  differs  but  little  from  the 
one  above  represented,  (677,  &c.)  being  the  same  as  that  described  in  page  433 
(241,  &c.)  excepting  the  funnel,  which  is  unnecessary  in  this  case. 

680.  Into  the  lower  end  of  the  cock  a  rod  of  iron  is  screwed  fast.  This  rod  is  of 
such  dimensions  as  to  extend  from  the  top  to  the  bottom  of  the  receiver,  and  is  sup- 
ported  within  it,  so  as  to  be  in  its  axis  or  every  where  equidistant  from  the  surface. 
Before  fastening  the  plate  into  the  situation  in  which  it  is  represented  in  the  figure, 
it  must  be  lifted  in  order  to  attach  the  leaf  metal  to  the  rod  with  the  aid  of  gum 
arable.  The  arrangements  being  so  far  completed,  the  cylindrical  receiver  having 
been  exhausted  by  means  of  the  air  pump,  the  cock,  regulating  the  communication 
with  that  instrument,  is  to  be  closed,  and  the  other  which  controls  the  entrance  of 
the  gas  is  to  be  opened.  By  these  means  the  leaves  burn  splendidly,  being  simulta- 
neously enveloped  in  an  atmosphere  of  chlorine,  which  rushes  in  to  supply  the  va- 
cuum caused  by  the  air  pump. 


*  The  metal  usually  employed  is  the  Dutch  gold  leaf  of  the  shops,  an  alloy  prin- 
cipally of  copper  and  zinc. 


CHLORINE. 


121 


681.  Another  method  of  performing  this  experiment  is  illustrated  by  fig.  2. 
FIG.  1.  FIG.  2. 


682.  The  metallic  leaves  being  suspended  from  the  plate  which  closes  the  bell,  B, 
and  this  bell  being  exhausted  of  air  by  means  of  the  pump,  chlorine  is  suddenly  ad- 
mitted into  it  by  the  glass  cock  from  the  bell  glass,  A,  previously  supplied  with 
the  gas. 

Spontaneous  Combustion  of  Phosphorus  in  Chlorine. 

683.  The  figure  at  the  top  of  the  next  page,  is  intended  to  convey  an  idea  of  the 
spontaneous  inflammation  of  phosphorus  in  chlorine,  by  means  of  an  apparatus  which 
enables  the  lecturer  to  perform  the  experiment  without  exposing  spectators  to  the 
fumes.     Let  there  be  a  cylindrical  glass  vessel,  eight  or  nine  inches  in  diameter, 
and  about  a  foot  in  height,  with  a  neck  about  four  inches  high,  and  one  and  a 
half  inches  in    bore  ;    the  whole  resembling  a  large  decanter  without  a  bottom, 
About  the  orifice  of  the  neck,  let  there  be  cemented,  air-tight,  a  brass  cap,  sur- 
mounted by   a  stuffing  box,  and  having  on  one  side  a  hole  communicating  with 
the  cavity  of  the  neck.     This  aperture  must  be  furnished  with  a  screw,  by  which  it 
may  be  opened  or  closed  at  pleasure.    Through  the  stuffing  box  a  copper  rod  passes, 
at  the  lower  end  of  which  a  glass  or  leaden  stopple  is  so  affixed,  as  to  close  the  low- 
er part  of  the  neck,  into  which  it  is  ground  to  fit  air-tight.     Over  this  stopple,  a  cup 
of  copper  is  soldered,  so  as  to  be  concentric  with  the  rod.     The  rod  terminates  above 
in  a  handle.     Within  the  cup,  let  ten  or  fifteen  grains  of  phosphorus  be  placed. 
This  is  easily  effected  when  the  cup  and  plug  are  depressed  into  the  lower  part  of 

16 


122 


INORGANIC    CHEMISTRY. 


the  cavity  of  the  vessel,  by  a  suitable  movement  of  the  sliding  rod.  In  the  next 
place  draw  up  the  cup  and  plug  into  the  neck,  so  as  nearly  but  not  entirely  to  close 
it,  and  sink  the  vessel  into  the  water  of  the  pneumatic  cistern  until  all  the  air  below 
the  neck  is  expelled  through  the  hole  in  the  side  of  it,  which  is  then  to  be  closed  by 
means  of  the  screw,  and  the  plug  twisted  and  drawn  into  its  place,  so  as  to  be  air- 
tight. After  filling  the  body  of  the  vessel  thus  with  water,  place  it  upon  the  shelf  of 
the  cistern.  Chlorine  may  now  be  allowed  to  occupy  three-fourths  of  the  space 
within  the  vessel  below  the  plug.  The  process  being  so  far  advanced,  it  is  only  ne- 
cessary, at  the  moment  when  it  is  desirable  to  produce  the  combustion,  to  depress 
the  plug,  and  of  course  the  cup  associated  with  it  containing  'the  phosphorus,  into 
the  cavity  supplied  with  the  chlorine .  The  phosphorus  soon  burns  actively,  although 
with  a  feeble  light.  The  increased  temperature  consequent  to  the  combustion, 
causes  the  gas  to  expand,  but  not  so  much  as  to  become  too  bulky  to  be  retained. 

684.  In  this  case  the  chlorine  forms  a  chloride  of  phosphorus,  which,  meeting  with 
water,  is  decomposed  into  phosphoric  and  muriatic  acids.  By  transferring  the  vessel, 
after  it  is  supplied  with  chlorine,  to  a  clean  porcelain  or  glass  dish,  covered  with 
pure  water,  the  products  of  this  combustion  might  be  saved,  and  would  of  course  in- 
crease  in  proportion  to  the  quantity  of  phosphorus  and  chlorine  employed.  On  a 
larger  scale,  this  process  might  be  resorted  to  advantageously  for  the  generation  of 
phosphoric  acid,  which  is  produced  when  the  proportion  of  chlorine  is  sufficient;  say 
four  cubic  inches  for  every  grain  of  phosphorus. 

Of  the  Compounds  of  Chlorine  with  Oxygen,  and  of  the  Nomenclature  of 
these  Compounds  and  others  formed  with  the  Basacigen  Class. 

685.  Consistently  with  the  French  nomenclature,  the  combinations  formed 
by  oxygen,  chlorine,  bromine,  iodine,  and  fluorine,  with  other  elements, 
have  been  distinguished  as  acids,  or  characterized  by  a  termination  in 
"  ide"  or  in  "  ure?  which  last  monosyllable,  when  there  has  been  no  in- 
tention of  altering  the  meaning,  has,  by  the  British  chemists,  been  translated 


CHLORINE.  123 

into  uret.  The  termination  in  ide,  which  is  common  to  both  languages,  is, 
by  Thenard,  and  other  eminent  French  authors,  restricted  to  the  binary  com- 
pounds of  oxygen  which  are  not  acid.  Analogous  compounds  formed  with 
the  halogen  elements,  chlorine,  bromine,  iodine,  fluorine,  cyanogen,  &c., 
have  by  the  same  writer  been  designated  by  the  termination  in  ure.  Thus 
we  have  in  his  work,  chlorures,  bromures,  iodures,  fluorures,  and  cyanures. 
Some  of  the  most  eminent  chemists  in  Great  Britain  have  distinguished 
the  elements  called  halogen  by  Berzelius,  together  with  oxygen,  as  sup- 
porters of  combustion,  and  have  designated  the  binary  compounds  made 
with  them,  when  not  acid,  by  the  same  termination  as  the  analogous  com- 
pounds of  oxygen.  Accordingly,  in  their  writings,  instead  of  the  names 
above  mentioned,  we  have  chlorides,  bromides,  iodides,  fluorides.  In  Hen- 
ry's Chemistry,  cyanure  is  represented  by  cyanide ;  in  Thomson's,  by  cyan- 
odide ;  and  in  Brande's  and  Turner's,  by  cyanuret.  I  shall  follow  the  prac- 
tice of  the  British  chemists  in  the  case  of  the  four  first  mentioned  com- 
pounds, extending  it  to  the  compounds  of  cyanogen,  as  Henry  has  done. 

686.  These  rules  of  nomenclature  will  be  considered  as  extending  to  all 
the  basacigen  class.  Of  course,  the  compounds  of  sulphur,  selenium  and 
tellurium,  when  not  acid,  will  be  designated  by  appellations  terminating  in 
ide.  In  lieu,  therefore,  of  sulphuret,  selenuret  and  telluret,  I  shall  in  com- 
mon with  Berzelius,  employ  the  words  sulphide,  selenide  and  telluride. 

COMPOUNDS  OF  CHLORINE  WITH  OXYGEN. 

With  1  atom,  or  §  volume  of  oxygen,  or  hypochlorous 
acid,      ....---         44 


687.  1  atom  or  1 
volume  of  chlorine 
equivalent  36,  forms 


With  4  atoms,  or  2  volumes  of  oxygen,  chlorous 
acid,  -  68 

With  5  atoms,  or  2^  volumes  of  oxygen,  chloric 
acid  -  -  76 

With  7  atoms,  or  3|  volumes  of  oxygen,  perchloric, 
or  oxychloric  acid,  -  92 

Of  Hypochlorous  Acid. 

688.  This  compound,  of  which  the  ingredients  are  stated  above,  (687,) 
is  generated  by  the  reaction  of  chlorine,  with  an  excess  of  finely  pulverized 
peroxide  of  mercury,  suspended  in  pure  water  by  agitation. 

689.  By  these  means,  the  chlorine,  agreeably  to  the  4th  case  of  affinity, 
(523,  &c.,)  combines  with  both  the  oxygen  and  mercury,  forming  two  com- 
pounds, a  bichloride  of  mercury,  and  a  protoxide  of  chlorine,  or  hypochlo- 
rous acid,  which  dissolves  in  the  water.     The  bichloride  combines  with  a 
portion  of  the  undecomposed  bioxide,  and  forms  a  kind  of  combination, 
generically  designated  as  oxychloride,  indicating  that  a  substance  so  called 
consists  of  an  oxide,  and  a  chloride.   "  The  oxychloride  formed  in  this  case, 
being  almost  insoluble,  is  separated  by  filtration.    A  more  concentrated  so- 
lution of  the  acid  is  procured  by  successive  distillations,  in  which  as  little 
heat  as  possible  should  be  used,  and  preferably  it  should  be  accomplished 
by  diminished  pressure.*' 

690.  Properties  of  Hypochlorous  Acid. — The  aqueous  solution  of  hy- 
pochlorous acid,  resulting  from  the  above  described  process,  is,  when  con- 
centrated, in  colour  slightly  yellow,  with  an  odour  strong  and  penetrating, 

*  For  the  purpose  of  distillation,  by  reduced  pressure,  the  apparatus  represented 
and  described  in  page  G9,  (398,)  might  be  used,  substituting  a  second  and  third  re- 
tort, well  refrigerated,  for  the  vessel,  B,  and  the  bottle,  C.  (188.) 


124  INORGANIC  CHEMISTRY. 

resembling  that  of  chlorine,  but  yet  differing  therefrom  perceptibly ;  upon 
the  skin  its  effects  are  similar  to  those  of  nitric  acid,  but  more  active.  Its 
bleaching  powers  are  eminently  great.  It  is  so  much  prone  to  decomposi- 
tion, as  to  undergo  that  process  spontaneously  at  ordinary  temperatures, 
beinff  resolved  into  chlorine  and  chloric  acid.  This  change  is  accelerated 
by  light,  and  ensues  immediately  from  direct  exposure  to  the  solar  rays. 
Bodies  full  of  sharp  corners,  (the  fragments  of  powdered  glass,  for  instance,) 
when  thrown  into  the  liquid  acid,  are  productive  of  an  evolution  of  chlorine 
with  brisk  effervescence.  The  oxydizing  powers  of  this  reagent  are  pow- 
erful but  various,  being  most  active  with  non-metallic  elementary  radicals, 
such  as  sulphur,  phosphorus,  and  selenium.  Each  of  these  it  readily  satu- 
rates with  oxygen,  and  likewise  iodine,  and  bromine,  which  are  thus  seve- 
rally converted  into  bromic  and  iodic  acid.  Its  reaction  with  gold  and  pla- 
tinum, is  but  feeble,  but  with  iron  and  silver  energetic.  The  former  is  con- 
verted into  an  oxide,  the  latter  into  a  chloride,  while  in  the  case  of  the  one, 
the  oxygen  escapes,  in  that  of  the  other  the  chlorine.  Mercury  it  converts 
into  an  oxide,  and  a  chloride,  which  form  an  oxychloride,  by  uniting  in 
their  nascent  state. 

Of  Gaseous  Hypochlorous  Acid. 

691.  Balard,  to  whom  we  are  indebted  for  our  knowledge  of  the  facts 
above  stated,  was  successful  in  procuring  hypochlorous  acid  in  the  gaseous 
form,  by  introducing  into  a  concentrated  aqueous  solution  over  mercury, 
anhydrous  nitrate  of  lime  in  successive  portions.     By  its  superior  affinity 
for  water,  the  nitrate  causes  the  evolution  of  the  acid  in  the  aeriform  state, , 
the  mercury  being  protected  by  the  interposed  solution  of  the  nitrate. 

692.  Properties  of  Gaseous  Hypochlorous  Acid. — The  gaseous  hypo- 
chlorous  acid  much  resembles  chlorine,  in  possessing  a  greenish  yellow 
colour.     Water  absorbs  100  times  its  own  volume  of  it. 

693.  A  slight  increase  of  temperature  is  sufficient  to  cause  hypochlorous 
acid  to  detonate,  and  though  less  explosive  than  chlorous  acid,  it  is  apt  to 
explode,  when  an  effort  is  made  to  transfer  it  from  one  bell  glass  to  another. 

694.  Its  composition  was  ascertained  by  Balard,  by  analyzing  the  gas- 
eous product  resulting  from  its  explosion,  by  which  it  was  found  to  consist 
of  one  volume  of  chlorine,  and  half  a  volume  of  oxygen,  as  already  stated. 
(638.) 

Of  Euchlorine  or  Impure  Chlorous  Acid. 

695.  In  the  last  edition  of  this  work,  euchlorine  was  treated  as  a  prot- 
oxide of  chlorine,  but  it  was,  at  the  same  time  mentioned,  that  doubts  ex- 
isted whether  the  gaseous  substance  known  by  this  appellation,  might  not 
be  a  mixture  of  chlorous  acid  with  chlorine.     These  doubts  appear  to  have 
been  succeeded  by  an  affirmative  conviction,  and  accordingly  I  have  omit- 
ted the  name  from  the  list  above  given,  of  the  definite  compounds  of  chlo- 
rine with  oxygen. 

696.  Euchlorine  is  obtained  by  heating  gently,  in  a  small  glass  retort, 
equal  parts  of  strong  muriatic  acid,  water,  and  chlorate  of  potash.     The 
retort  should  only  be  subjected  to  the  flame  of  a  small  spirit  lamp,  or  an 
inflamed  jet  of  hydrogen,  which  should  be  so  situated  as  not  to  heat  the 
body  of  the  retort  above  the  part  containing  the  liquid ;  as  this  may  cause 
an  explosion.     It  is  advantageous  to  interpose,  as  a  support  for  the  retort, 
a  plate  of  tin,  having  a  circular  aperture  of  about  an  inch  and  a  half  in 
diameter.     By  these  means,  the  application  of  the  heat  may  be  sufficiently 
restricted. 


CHLORINE.  125 

697.  The  gas  may  be  received  over  mercury,  although  not  without 
inconvenience;  since  by  its  decomposition,  in  consequence  of  the  large  pro- 
portion of  free  chlorine  with  which  it  is  associated,  the  mercury  is  super- 
ficially converted  into  a  subchloride.     But,  while  the  covering  thus  formed, 
protects  the  surface  of  the  metal  from  further  erasion,  it  also,  by  coating 
the  internal  surface  of  the  glass,  hides,  more  or  less,  the  remarkably  deep 
greenish-yellow  colour  of  the  gas  from  the  eye  of  the  spectator. 

698.  Agreeably  to  Soubieran,  when  the  gas  thus  obtained  is  passed 
through  a  tube,  replete  with   protochloride  of  mercury,    (calomel,)   this 
chloride  absorbs  an  additional  atom  of  chlorine,  and  thus  brings  the  chlo- 
rous acid  to  a  state  of  purity.     The  rationale  of  the  evolution  of  the  mix- 
ture known  as  euchlorine,  seems  to  be  as  follows.     By  double  elective 
affinity,  there  is  a  reciprocal  decomposition  of  the  potassa  and  chlorohydric 
acid,  causing  the  separation  of  the  chloric  acid,  containing  five  atoms  of 
oxygen.     Consequently,  by  the  reaction  with  these  atoms,  a  further  dehy- 
drogination  of  chlorine  ensues,  causing  a  portion  to  be  set  free,  while 
another  portion  retains  enough  oxygen  to  constitute  chlorous  acid. 

Process  for  elaborating  pure  Chlorous  Acid  directly. 

699.  Pure  chlorous  acid  is  obtained  by  distilling  one  part  of  chlorate  of 
potash,  fused  into  a  mass,  at  the  bottom  of  a  small  glass  retort,  with  about 
3^  parts  of  concentrated  sulphuric  acid,  and  receiving  the  gaseous  product 
over  mercury.     The  evolution  of  the  gas  takes  place  without  heat  at  first, 
but  to  be  completed  requires  a  temperature  near  to  140°.     This  should  not 
be  exceeded,  and  the  heat  should  be  restricted  to  the  bottom  of  the  retort,  as 
in  the  case  of  euchlorine.     The  process  is  replete  with  danger,  as  from 
slight  causes  this  gas  explodes  with  surprising  force. 

700.  Rationale. — By  the  action  of  sulphuric  acid  on  chlorate  of  potash, 
two  compounds  are  produced,  chlorous  and  oxychloric  acid.    The  former  is 
evolved  in  the  gaseous  state,  the  latter  remains  in  union  with  the  potash. 
It  would  seem  as  if  one  portion  of  the  chloric  acid  were  displaced  from  its 
union  with  the  potash  by  the  superior  affinity  of  the  sulphuric  acid,  and 
then  relinquished  a  part  of  its  oxygen  to  another  portion  of  the  same  acid, 
still  in  union  with  the  alkali.     The  chlorate  of  potash  is  thus  partially 
converted  into  an  oxychlorate.     The  deoxidized  chloric  acid  constitutes  a 
compound  which  is  designated  by  Berzelius  as  chlorous  acid.     By  others, 
it  has  been  variously  designated  as  the  tritoxide,  quadroxide,  or  peroxide  of 
chlorine,  in  consonance  with  the  different  impressions  entertained  of  its 
properties,  or  composition. 

Properties  of  pure  Chlorous  Acid. 

701.  Chlorous  acid  gas  has  a  yellow  colour,  which  is  deeper  than  that 
of  chlorine.     Its  odour  is  somewhat  aromatic,  and  bears  no  resemblance 
to  that  of  chlorine.     It  whitens  a  solution  of  litmus,  without  reddening  it. 
When  subjected  to  an  electric  spark,  or  to  a  temperature  of  212°,  it  ex- 
plodes with  great  violence,  giving  out  light  and  heat,  and  being  converted 
into  chlorine  and  oxygen.     Agitating  the  gas  with  mercury  will  sometimes 
produce  the  same  result.    Water  absorbs  seven  times  its  volume  of  chlorous 
acid  gas,  acquiring  a  deep  yellow  colour,  and  a  peculiar  acrid  taste,  which 
is  nevertheless  not  at  all  acid.    The  aqueous  solution,  when  added  in  small 
quantities,  possesses  the  power  of  reddening  litmus,  and  when  exposed 
directly  to  the  sun's  rays  evolves  chlorine,  while  oxychloric  acid  remains 
in  solution.     In  a  diffuse  light  it  takes  several  weeks  to  effect  this  decom- 
position, and  it  does  not  take  place  at  all  in  the  dark.     Faraday  has  found 


126  INORGANIC  CHEMISTRY. 

that  chlorous  acid  gas  may  be  liquefied  by  subjecting  it  to  great  pressure, 
The  resulting  liquid  is  of  a  yellow  colour. 

A  convenient  and  safe  Method  of  effecting  the  Explosion  of  Euchlorine. 


702.  A  convenient  and  safe  method  of  effecting  the  explosion  of  euchlorine  per  se 
is  represented  in  the  preceding  figure.    The  gas  being  .introduced  into  a  strong  tube 
of  about  §ths  of  an  inch  in  diameter,  and  fifteen  inches  in  length,  over  mercury,  on 
applying  a  heated  metallic  ring,  an  explosion  ensues.     The  gas  at  the  same  time 
loses  its  greenish-yellow  colour,  and  increases  in  bulk.     The  chlorine  is  subsequently 
absorbed  by  the  mercury. 

703.  Thenard  advises  the  application  of  a  spirit  lamp  to  produce  the  necessary 
temperature.     It  is  easier  and  more  safe  to  use  the  hot  ring.     The  tube  is  of  neces- 
sity supported  by  an  iron  wire,  which  has  been  overlooked  in  sketching  the  figure. 

704.  Rationale. — Agreeably  to  the  idea  that  aeriform  fluids  owe  their  repulsive 
power  to  caloric,  there  ought,  after  an  evolution  of  heat,  to  be  a  reduction  of  volume 
in  any  gaseous  compound;  but  by  the  decomposition  of  euchlorine,  although  caloric 
is  evolved  with  explosive  violence,  the  volume  of  the  gaseous  matter  is  increased. 

705.  The  only  explanation  which  I  can  give,  is,  that  the  capacity  for  caloric  of  the 
compound  in  this  case,  as  in  others,  is  greater  than  the  sum  of  the  capacities  of  the 
constituents.     Why  the  capacity  of  the  compound  should  be  greater,  and  wherefore 
caloric  should  be  more  forcibly  attracted  by  an  atom  of  oxygen  and  an  atom  of  chlo- 
rine when  united  than  when  separate,  I  cannot  explain.     This  and  other  analogous 
mysteries  are  no  doubt  connected  with  those  of  electricity,  galvanism,  and  electro- 
magnetism. 

Apparatus  for  exhibiting  safely  the  Explosion  of  Chlorous  Acid. 

706.  The  adjoining  figure  represents  an  apparatus 
for  exhibiting,  without  danger  to  the  spectators,  the 
detonation  of  chlorous  acid. 

707.  Into  a  tube  of  nearly  f  ths  of  an  inch  in  dia- 
meter, and  sealed  at  one  end,  about  as  much  chlorate 
of  potash  is  introduced  as  will  rise  above  the  bottom 
about  one  inch.     The  mass  thus  situated  is  to  be 
fused  by  means  of  a  spirit  lamp,  or  chauffer. 

708.  The  tube,  being  then  charged  with  a  due 
proportion  of  sulphuric  acid,  is  corked  gently,  and 
suspended  within  a  stout  glass  cylinder,  as  in  the 
drawing.     It  is  then  surrounded,  near  the  bottom,  by 
another  tube,  supplied  with  boiling  water.     At  first, 
the  hot  water  is  applied  only  to  that  part  of  the  tube 
which  contains  the  salt;  but  as  soon  as  the  inner 
tube  is  pervaded  by  a  greenish-yellow  colour,  de- 
monstrating the  evolution  of  the  chlorous  acid,  the 
outer  tube  containing  the  water  is  to  be  raised,  so 
that  the  gas  may  be  generally  heated  by  it.     An 
explosion  soon  follows,  from  the  influence  of  which 
spectators  are  protected  by  the  glass  cylinder. 

Preparation  of  Chloric  Acid. 

709.  When  a  solution  of  potassa  (oxide  of 
potassium)  or  the  carbonate  of  this  alkali  is 


CHLORINE.  127 

impregnated  copiously  with  chlorine,  crystals  precipitate,  which  consist  of 
chloric  acid  in  union  with  potassa.  If  to  a  solution  of  the  chlorate  of 
potassa  thus  formed,  fluohydrosilicic  acid  be  added,  an  almost  insoluble 
fluosilicate  of  potassium  precipitates.  From  this  an  aqueous  dilute  solu- 
tion of  the  desired  acid  may  be  obtained  by  filtration. 

710.  If,  in  lieu  of  a  solution  of  potassa,  water  holding  baryta  suspended, 
be  impregnated  with  chlorine,  a  chlorate  of  baryta  may  be  procured,  from 
which  the  baryta  may  be  precipitated  by  employing,  as  nearly  as  possible, 
an  equivalent  of  sulphuric  acid.     It  was  by  this  process  that  Chenevix 
discovered  chloric  acid ;  but  it  is  alleged  that  when  thus  procured,  it  retains 
a  minute  proportion  of  sulphuric  acid.     ' 

711.  Properties. — Chloric  acid,  thus  procured,  is  inodorous,  colourless, 
sour  and  astringent.     It  does  not  precipitate  solutions  of  lead,  mercury,  or 
silver,  which,  for  a  great  majority  of  the  compounds  of  chlorine,  are  infal- 
lible tests.     When  concentrated  by  evaporation,  at  a  gentle  heat,  it  is  re- 
duced to  an  oleaginous  consistency,  and  acquiring  a  yellowish  tint,  also  an 
odour  like  that  of  nitric  acid.     In  this  state  it  ignites  paper,  and  other  or- 
ganic products,  and  is  capable  of  converting  alcohol  into  acetic  acid.     It  is 
decomposed  by  many  substances  having  an  affinity  for  oxygen;  and  yet, 
in  acting  upon  iron  or  zinc,  is  said  to  cause  the  oxidizement  of  these  metals, 
not,  like  nitric  acid,  at  its  own  expense,  but  by  the  decomposition  of  water, 
of  which  the  hydrogen  is  in  consequence  evolved.     Many  bodies  which  do 
not  otherwise  react  with  it,  cause  its  decomposition  when  aided  by  the  so- 
lar rays. 

Of  Oxycliloric  or  Perchloric  Acid. 

712.  Preparation. — After  the   chlorous  acid  has  been  liberated  from 
chlorate  of  potash,  the  residue  consists  partially  of  oxychlorate  of  potash, 
as   already  stated.  (700.)      This  is  mingled   with  bisulphate  of  potash 
formed  at  the  same  time,  but  may  be  separated  by  repeated  solution  and 
crystallization,  as  the  bisulphate  is  more  soluble.*" 

713.  Oxychloric  acid  may  be  obtained  from  oxychlorate  of  potash  by 
distillation  in  a  retort  with  its  own  weight  of  sulphuric  acid,  diluted  with  a 
like  weight  of  water  at  the  temperature  of  280°.     It  is  purified  by  carefully 
precipitating  the  sulphuric  acid  which  comes  over  with  it,  by  means  of  ba- 
rytic  water,  and  redistillation. 

714.  Properties. — Like  chloric  acid,  it  is  insusceptible  of  the  gaseous 
form,  and,  as  a  liquid,  exists  only  in  combination  with  water,  being  limpid, 
colourless,  and  having  a  lively  acid  taste.     It  reddens,  but  does  not  subse- 

*  In  evolving  oxygen  from  chlorate  of  potassa,  by  means  of  a  porcelain  retort 
and  chauffer  of  coals,  it  excited  surprise,  that  while  the  greater  part  of  the  gas  could 
be  obtained  in  a  glass  retort,  without  softening  the  glass,  there  was  a  portion  which 
required  a  higher  temperature  than  that  which  flint  glass  is  capable  of  enduring. 
While  contemplating  some  experiments  for  the  explanation  of  these  phenomena,  1 
learned  that  Soubieran  had  furnished  the  true  explanation  of  the  mystery.  He  had 
ascertained  that  one  portion  of  the  salt,  receiving  two  equivalents  of  oxygen  from 
another,  became  converted  into  an  oxychlorate,  of  which  the  decomposition  was 
more  difficult  than  that  of  the  chlorate.  Subsequently  this  process  has  been  resorted 
to  by  my  young  friend  and  late  pupil,  Mr.  Boye,  and  my  son,  to  obtain  oxychlorate, 
for  which  purpose  they  have  subjected  a  pound  of  chlorate  of  potash,  at  a  time,  to 
partial  decomposition.  The  mass  which  remains  after  all  the  oxygen  has  been  ex- 
pelled, that  can  be  extricated  without  softening  flint  glass,  consists  of  a  mixture  of 
chloride  of  potassium  and  of  oxychlorate  of  potash.  As  of  all  the  salts  of  potassa, 
that  in  question  is  the  most  sparingly  soluble  in  water  at  60°,  by  solution  in  this 
liquid  while  boiling  hot,  and  cooling  the  solution,  the  salt  precipitates,  and  may  bo 
purified  by  repeating  this  part  of  the  process. 


128  INORGANIC  CHEMISTRY. 

quently  bleach  an  infusion  of  litmus.  It  is  decomposed  neither  by  the  so- 
lar rays,  sulphurous  acid,  nor  sulphuretted  hydrogen.  It  dissolves  zinc  and 
iron  with  disengagement  of  hydrogen.  It  exercises  strong  affinities,  and  is 
the  most  enduring  of  the  combinations  of  chlorine  with  oxygen  ;  which  is 
the  more  surprising,  as  it  is  in  general  true  that  in  proportion  as  any  one 
ingredient  predominates  in  a  compound,  it  is  the  more  easily  separated  in 
part. 

715.  By  the  reaction  of  sulphovinic  acid,  with  oxychlorate  of  barytes, 
Mr.  Boye  and  my  son  have  procured  an  ether,  which  in  its  explosive  ener- 
gy, is  scarcely  equalled  by  the  chloride  of  nitrogen.     It  is  I  believe  the  only 
ethereal  compound  which  is  per  se  explosive,  or  which  detonates  from  a 
mechanical  shock. 

SECTION  III. 

OF   BROMINE. 

716.  This  name  has  been  given  to  a  substance  analo- 


gous to  chlorine,  from  the  Greek  fyvw,  fetidity. 

717.  Bromine  was  discovered  by  Balard  in  1826,  at  the 
salt  works  of  Montpelier  in  France,  in  the  mother  waters 
of  marine  salt,  in  the  state  of  bromide  of  sodium  or  mag- 
nesium.    Since  then  it  has  been  found  in  the  water  of  the 
Dead  Sea,  and  in  the  greater  part  of  the  salt  springs  of  the 
continent,  especially  those  of  Germany.    In  those  of  Theo- 
dorshalle  near  Kreuznach,  a  sufficient  quantity  has  been 
found,  to  make  it  profitable  to  effect  its  extraction.     Com- 
mon salt,  in  its  natural  state,  often  contains  traces  of  the 
bromides  of  sodium  or  magnesium. 

718.  Preparation.  —  The  mother  water  of  marine,  or  com- 
mon salt,  is  impregnated  with  chlorine,  until  it  acquires  a 
hyacinth-red  tinge.     The  chlorine  combines  with  the  hy- 
drogen and  magnesium  of  a  bromide  of  magnesium,  which 
exists  in  that  water.     The  bromine,  thus  displaced,  min- 
gles with  the  water,  which  is  to  be  washed  with  ether. 
The  resulting  ethereal  solution  of  bromine,  being  treated 
with  potash,  a  bromide  of  potassium  is  produced,  which, 
heated  in  a  retort  with  diluted  sulphuric  acid  and  manga- 
nese, yields  bromine,  as  chlorine  is  obtained  from  a  chlo- 
ride by  like  treatment. 

719.  Properties.  —  Bromine  is  a  liquid,  but  is  so  volatile, 
that  a  single  drop  is  sufficient  to  fill  a  flask  with  its  red- 
dish-brown vapour.  The  specific  gravity  of  bromine  is  2.966, 
being  nearly  three  times  the  weight  of  its  bulk  of  water. 
It  freezes  at  a  temperature  of  from  7°  to  12°  below  zero. 


BROMINE.  129 

It  lias,  when  frozen,  a  crystalline  and  leafy  texture,  with  a 
lead-gray  colour,  and  a  lustre  almost  metallic.  It  boils  at 
the  temperature  nearly  of  89°,  forming  a  vapour  resembling 
that  of  nitrous  acid,  and  more  than  five  times  as  heavy  as 
atmospheric  air.  It  does  not  conduct  electricity.  Flame 
is  extinguished  in  the  vapour  of  bromine,  acquiring  a  green- 
ish colour  previous  to  its  extinction.  Bromine  is  slightly 
soluble  in  water.  Its  solubility  is  not  sensibly  augmented 
by  heat.  The  solution  has  an  orange  colour,  and  emits 
red  fumes.  In  alcohol  it  is  more  soluble,  than  in  water, 
and  in  ether  still  more  so  than  in  alcohol. 

720.  It  acts  upon  vegetable  colouring  matter  and  or- 
ganic products,  like  chlorine,  in  general,  decomposing  them 
in  consequence  of  its  affinity  for  hydrogen.    Bromine  forms 
with  starch,  a  yellow  compound.      It  corrodes  the  skin, 
imparting  a  yellow  tinge,  which  endures  till  the  skin  is  re- 
novated.    In  its  habitudes  with  oxygen,  hydrogen,  sulphur, 
and  phosphorus,  and  the  metals,  it  has  a  great  analogy 
with  chlorine,  but  generally  its  affinities  are  not  so  strong. 
From  its  reaction  with  potassium,  an  intense  and  almost 
explosive  combustion  is  said  to  ensue.    When  taken  inter- 
nally, bromine  acts  as  a  virulent  poison. 

721.  Bromine  is  supposed  to  be  one  of  the  active  sub- 
stances in  mineral  springs,  especially  in  those  which  con- 
tain common  salt.     By  means  of  nitric  acid  it  may  be  ob- 
tained in  the  form  of  a  deep  brown  precipitate,  from  the 
mother  waters  in  which  it  exists,  but  there  is  much  lost  by 
its  solution,  and  subsequent  volatilization  during  the  eva- 
poration of  the  solvent. 

Experimental  Illustration. 

722.  Bromine  exhibited  as  a  liquid;  also  in  the  state  of 
vapour. 

COMPOUNDS  OF  BROMINE  WITH  OXYGEN  AND  CHLORINE. 

Of  Bromic  Acid. 

723.  Bromine  forms  but  one  compound  with  oxygen,  called  bromic  acid, 
which  was  discovered  by  Balard. 

7:24.  Preparation. — When  sulphuric  acid  is  added  to  bromate  of  baryta 
dissolved  in  water,  a  sulphate  of  baryta  is  precipitated,  and  bromic  acid  re- 
mains in  solution,  which  may  afterwards  be  concentrated  by  evaporation. 

725.  Properties. — Bromic  acid,  thus  obtained,  is  a  liquid  of  the  consist- 
17 


130  INORGANIC  CHEMISTRY. 

ence  of  syrup.  If  we  endeavour  to  remove  any  farther  portion  of  the  wa- 
ter, the  acid  is  decomposed  into  oxygen  and  bromine.  Bromic  acid  first 
reddens  and  then  whitens  litmus  paper.  It  has  a  strong  taste,  acid  but  not 
caustic.  Its  odour  is  hardly  perceptible.  Sulphurous  and  phosphorous 
acid,  and  all  the  acids  which  have  hydrogen  for  their  radical,  decompose  it 
by  removing  the  oxygen.  Concentrated  sulphuric  acid  produces  the  same 
effect  by  removing  the  water,  without  which  bromic  acid  cannot  exist. 

726.  Bromic  acid  is  composed  of  one  atom  of  bromine  78,  and  five  of 
oxygen  40.     Its  equivalent  is  therefore  118. 

Of  Chloride  of  Bromine. 

727.  When  a  current  of  chlorine  is  passed  through  bromine,  a  liquid 
compound  is  produced  of  a  reddish-yellow  colour,  but  not  so  deep  as  that  of 
bromine.     This  liquid  is  volatile,  of  an  intolerable  smell,  producing  tears ; 
has  an  excessively  disagreeable  taste,  and  a  colour  resembling  that  of  eu- 
chlorine.     Water  dissolves  this  chloride,  acquiring  the  power  of  bleaching 
litmus.     Bases  produce  with  its  ingredients,  a  bromate,  a  bromide,  and  a 
chloride. 


SECTION  IV. 

OF  IODINE.    , 

728.  Iodine  has  been  found  in  various  sea  plants,  espe- 
cially the  common  sponge,  also  in  mineral  waters  in  a  va- 
riety of  regions  of  the  earth,  remote  from  each  other.     It 
exists  also  in  combination  with  various  fossils.     From  the 
experiments  of  my  late  friend  Dr.  Steel,  of  Saratoga,  and 
others,  it  appears  to  be  an  ingredient  in  some  of  the  mine- 
ral waters  of  that  place. 

729.  Preparation. — Iodine  is  obtained  from  the  lixivium 
of  kelp,  from  which  carbonate  of  soda  is  manufactured. 
After  all  the  soda  has  been  crystallized,  the  residuum  is 
concentrated,  and  being  heated  with  sulphuric  acid,  in  a 
retort,  the  iodine  passes  over,  and  condenses  in  shining 
crystals  of  an  intense  purple  or  black  colour. 

730.  Iodine  may  be  precipitated  from  the  mother  waters 
of  salts,  with  which  it  is  naturally  associated,  by  a  mixture 
of  eight  parts  of  sulphate  of  copper,  and  one  of  green  sul- 
phate of  iron.     From  this  precipitate  iodine  may  be  ob- 
tained by  intense  ignition,  in  a  retort,  with  an  equal  quan- 
tity of  dry  peroxide  of  manganese. 

731.  Properties. — When  solid,  iodine  is  of  a  bluish-black 
colour,  friable,  and  almost  insoluble.     It  stains  the  skin  yel- 
low.    It  fuses  at  225°  and  volatilizes  at  350°,  in  a  beautiful 


IODINE.  131 

violet  vapour.  Hence  its  name,  from  the  Greek  ,»^5,  violet- 
coloured.  Its  taste  is  acrid  and  hot,  and  continues  for  a 
long  time  in  the  mouth.  When  taken  internally,  it  acts  as 
a  poison.  It  is  incombustible  either  in  oxygen,  or  atmo- 
spheric air;  but  forms  acids  severally  with  oxygen,  chlo- 
rine, and  hydrogen,  called  iodic,  chloriodic  and  iodohydric* 
acids.  In  its  habitudes  with  the  Voltaic  pile,  it  is  more 
electro-negative  than  any  other  matter,  excepting  oxygen, 
sulphur,  chlorine,  bromine,  and  probably  fluorine.  With 
all  the  varieties  of  fecula,  starch,  sago,  arrow  root,  &c.,  io- 
dine produces  an  intensely  blue  colour;  so  that  these  sub- 
stances are  reciprocally  tests  for  each  other.  When  mois- 
tened it  vaporizes  perceptibly,  producing  an  odour  similar 
to  that  of  chlorine,  but  which  yet  has  a  peculiar  character. 
The  specific  gravity  of  iodine  in  the  solid  state  is  4.946. 

732.  The  vapour  of  iodine  is  alleged  to  have  the  highest 
specific  gravity  of  any  known  aeriform  fluid,  being  8.716, 
or  nearly  nine  times  as  heavy  as  atmospheric  air.     In  con- 
densing it  is  peculiarly  prone  to  crystallize,  assuming  the 
form  of  an  elongated  octoedron,  with  a  rhomboidal  base. 
Water  does  not  dissolve  more  than  TsWth  of  its  weight, 
acquiring  a  russet  colour,  but  no  taste.     When  the  water 
has  a  salt  added  to  it,  especially  muriate  or  nitrate  of  am- 
monia, it  dissolves  a  larger  quantity  of  iodine.     The  aque- 
ous solution  does  not  give  out  oxygen  in  the  solar  rays, 
nor  destroy  vegetable  colours.     Iodine  has  a  great  analogy 
to  chlorine  and  bromine,  though  more  feeble  in  its  affini- 
ties than  either. 

733.  Soubieran  recommends   that,    in  order   to    apply 
starch  as  a  test  for  iodine,  the  liquid  to  be  essayed  should 
be  rendered  slightly  acid  by  means  of  nitric  acid.     After 
this  addition  and  that  of  the  starch,  it  will,  in  the  course 
of  an  hour,  acquire  successively  a  reddish  tint,  a  brownish- 
red,  a  blue,  and  finally  a  black  colour;  or,  in  other  words, 
the  blue  by  its  intensity,  becomes  equivalent  to  black.     It 
has  been  alleged  that  in  this  way  iodine  may  be  detected 
in  a  liquid  of  which  it  forms  only  the  4TFoooth  part. 

734.  Another  mode  is  to  include  the  liquid  to  be  tested 
in  a  bottle  made  air-tight  by  means  of  a  cork,  from  which 
is  suspended  a  piece  of  moist  paper  sprinkled  with  finely 

*  The  term  hydriodic  has  hitherto  been  applied  to  this  acid,  but  Thenard,  as  well 
as  myself,  calls  it  iodohydric  acid.  The  considerations  which  induced  me  to  make 
this  change  will  be  given  hereafter. 


132 


INORGANIC    CHEMISTRY. 


powdered  starch.  If  iodine  be  present,  it  will  tinge  the 
starch.  It  is  allowed  by  Baup  that  iodine  may  be  thus 
discovered,  when  existing  in  a  liquid,  in  a  proportion  no 
greater  than  that  of  a  millionth. 

735.  Balard  recommends  that,  after  boiling  the  liquid 
with  a  small  quantity  of  starch,  a  solution  of  chlorine  in 
water  be  added  by  means  of  a  tube  descending  to  the  bot- 
tom.    The  chlorine,  at  the  line  of  contact,  disengages  the 
iodine  from  its  combinations,  and  enables  it  to  act  upon 
the  starch.     I  resorted  to  a  similar  process,  about  twenty 
years  ago,  using  sulphuric  acid  in  the  manner  in  which  the 
chlorine  is  employed  by  Balard. 

Experimental  Illustrations. 

736.  A  glass  sphere  containing  iodine,  on  being  warm- 
ed, appears  filled  with  a  violet-coloured  vapour. 

737.  To  a  large  glass  vessel,  containing  some  boiled 
starch  diffused  in  water,  a  small  quantity  of  iodine  being 
added,  the  fluid  becomes  intensely  blue. 

Process  for  the  extemporaneous  Evolution  of  Iodine. 

738.  Heat  nearly  to  the  tem- 
perature of  ebullition  about  two 
ounces  of  concentrated  sulphuric 
acid,  in  a  glass  globe  like  that  re- 
presented in  this  figure. 

739,  It  is  preferable  to  have 
the   whole  of  the  globe  heated, 
with  due  caution,  over  a  large 
charcoal  fire.  Then  quickly  trans- 
ferring it  to  the  iron  tripod,  pre- 
viously   heated,    and    furnished 
with    a   small  bed  of  hot  sand, 
throw  into  the  acid  about  half  a 
drachm  of  iodide  of  potassium, 
sometimes    called   hydriodate  of 
potash.     Instantaneously  the  ca- 
vity of  the  globe  will  become  re- 
plete with  the  splendid  violet  va- 
vour  of  iodine,  which  will  soon 
after  condense,  on  those  portions 
of  the  glass  which  are  first  re- 
frigerated, in  crystals,  symmetri- 
cally arranged,  of  great  beauty 
rind  unusual  si/.e. 


IODINE.  133 


COMPOUNDS  OF  IODINE  WITH  OXYGEN. 

Of  lodic  Acid. 

740.  When  iodine  is  subjected  to  a  current  of  chlorous  acid  gas,  previ- 
ously dried  by  passing  over  chloride  of  calcium,  the  gas  is  absorbed,  and  a 
yellow  liquid  produced.    From  this,  heat  expels  all  the  chlorine  of  the  acid, 
while  its  oxygen,  uniting  with  the  iodine,  forms  iodic  acid. 

741.  Properties. — Iodic  acid  is  an  inodorous  crystalline  solid,  much 
heavier  than  water,  with  an  acid  and  astringent  taste.     It  deliquesces  in 
moist  air,  but  remains  unaltered  when  the  air  is  dry.    In  water  it  is  soluble, 
but  is  precipitated  from  it  by  alcohol,  in  which  it  is  insoluble.     Its  aqueous 
solution  first  reddens  and  then  whitens  litmus.     With  a  great  number  of 
salifiable  bases  it  forms  salts,  which  detonate  if  mingled  and  ignited  with 
any  dry  combustible  matter.     In  common  with  bromic  acid,  it  is  decom- 
posed by  those  acids  which  have  hydrogen  for  their  radical,  and  by  many 
others  which  have  not  their  highest  proportion  of  oxygen.     It  contains  one 
atom  of  iodine,  and  five  of  oxygen. 

Of  Hyperiodic  and  lodous  Acid. 

742.  An  acid,  containing  more  oxygen  than  iodic,  has  been  recently  dis- 
covered by  Magnus,  to  which  the  name  of  hyperiodic  has  been  given.   But 
little  has  been  ascertained  respecting  its  properties.    Sementini  has  asserted 
that  he  has  discovered  two  additional  compounds  of  oxygen  with  iodine, 
one  of  which  he  calls  oxide  of  iodine,  the  other  iodous  acid.     Their  exist- 
ence, however,  requires  farther  confirmation. 

Of  the  Chlorides  of  Iodine. 

743.  According  to  Thenard,  chlorine  forms  with  iodine  a  protochloride 
and  a  perchloride.     The  former  contains  one  atom  of  each  ingredient,  the 
latter  consists  of  five  atoms  of  chlorine  and  one  of  iodine.     The  protochlo- 
ride is  the  chloriodic  acid  of  Davy. 

744.  To  the  perchloride  the  name  of  perchloriodic  acid  may  be  due. 
Thenard  awards  the  appellation  of  acid  to  neither.     Chloriodic  acid  is  ob- 
tained by  subjecting  iodine  in  excess,  to  the  action  of  chlorine.     A  liquid  is 
produced  of  a  deep  reddish-brown  colour,  much  heavier  than  water,  and 
having  in  its  mechanical  properties  a  great  analogy  to  bromine.     It  has  an 
acid  taste,  and  reddens  litmus.     Water  dissolves  it  without  sustaining  or 
causing  any  decomposition,  but  abandons  it  to  sulphuric  ether.     If  the 
abovementioned  pi-ocess  be  so  varied  as  to  have  an  excess  of  chlorine,  per- 
chloriodic acid  is  produced,  which  is  a  crystalline  and  volatile  substance  of 
a  yellowish-white  colour,  and  emitting  an  effluvium  so  irritating  as  to  pro- 
duce tears  and  a  sense  of  suffocation. 

Of  the  Bromides  of  Iodine. 

745.  Bromine  combines  with  iodine  in  two  proportions.   A  protobromide 
is  obtained  when  iodine  is  subjected  in  excess  to  the  action  of  bromine.     It 
is  solid,  and  when  warmed  affords  reddish-brown  vapours,  which  condense 
into  crystals  of  the  same  tinge,  in  shape  resembling  fern  leaves.     By  the 
same  .process,  when  the  proportions  are  reversed,  a  perbromide  results, 


134  INORGANIC  CHEMISTRY. 

which  is  liquid.  Both  of  these  bromides  are  soluble  in  water,  and  bleach 
without  reddening  litmus.  Subjected  to  the  action  of  the  Voltaic  pile,  bro- 
mine goes  to  the  positive,  iodine  to  the  negative  pole. 


SECTION  V. 

OF    FLUORINE. 

746.  In  the  last  edition  of  this  Compendium  it  was  stated,  that  an  ele- 
mentary body  bearing  the  name  at  the  head  of  this  section,  was  inferred  to 
exist  by  many  chemists ;  and  that  I  had  no  doubt  as  to  the  existence  of  flu- 
orine.    Since  that  statement  was  written,  Baudrimont  has  succeeded  in  ob- 
taining this  interesting  and  energetic  element,  by  passing  fluoride  of  boron 
over  red-hot  minium,  or  preferably  by  heating  a  mixture  of  intimately  min- 
gled chloride  of  calcium  and  black  oxide  of  manganese,  with  concentrated 
sulphuric  acid.     It  is  to  be  regretted  that  this  process  does  not  evolve  fluo- 
rine in  a  state  of  purity,  in  consequence  of  the  simultaneous  evolution  of 
the  fluohydric  and  fluosilicic  acids  in  a  small  proportion. 

747.  Properties. — Fluorine  is  described  as  a  gas  of  a  yellowish-brown 
colour,  with  an  odour  like  that  of  chlorine  mingled  with  a  smell  of  burnt 
sugar.     It  combines  directly  with  gold  but  not  with  glass.     The  observa- 
tions which  have  been  made  upon  it,  so  far  as  they  extend,  justify  the  in- 
ferences respecting  its  properties,  to  which  previous  knowledge  and  reason- 
ing had  given  rise ;  and  go  to  confirm  its  pretensions  to  a  place  among  the 
halogen  bodies  of  the  basacigen  class.  (627,  &c.)    (633,  &c.) 

748.  As  there  are  no  known  compounds  of  fluorine  with  any  of  the  ele- 
ments comprised  in  the  class  to  which  it  belongs,  consistently  with  the  ar- , 
rangement  to  which  I  have  declared  my  intention  to  adhere,  no  further 
consideration  can  be  given  to  it,  until  the  bodies  are  treated  of  with  which 
its  most  important  combinations  are  formed. 


SECTION  VI. 

OF    SULPHUR. 

749.  Sulphur  is  a  mineral  production,  well  known  in  com- 
merce under  the  name  of  brimstone.  It  is  sold  both  in 
rolls  and  in  flowers.  It  is  found  pure  in  the  vicinity  of 
volcanoes,  of  which  it  is  a  product.  In  combination  with 
metals  it  is  widely  disseminated.  From  some  of  its  me- 
tallic sulphides,  which  are  known  under  the  name  of  sul- 
phurets,  or  pyrites,  it  may  be  obtained  in  the  pulverulent 
form,  to  which  the  name  of  flowers  has  been  given,  by 
sublimation. 


SULPHUR.  135 

750.  Properties. — Sulphur  is  yellow,  inodorous,  and  in- 
sipid, becomes  electric  by  friction,  and  is  liable  by  the 
warmth  of  the  hand  to  be  fractured  with  a  slight  noise.    It 
evaporates  and  burns  with  a  feeble  flame  at  180°,  and 
melts  at  225°,  and  by  pouring  out  the  liquid  portion,  after 
the  mass  is  partially  congealed,  it  may  be  obtained  in 
crystals.     In  close  vessels  at  the  temperature  of  600°  it 
vaporizes,  or  sublimes,  and  afterwards  condenses  in  the 
well  known  form  of  flowers  as  above  stated.     The  flowers 
are  by  the  microscope  ascertained  to  be  crystalline,  and 
are  generally  contaminated  by  a  minute  portion  of  sulphu- 
rous acid,  which  may  be  removed  by  repeated  washing. 

751.  All  the  metals,  when  presented,  in  thin  leaves  or 
powder,  to  the  vapour  of  sulphur  without  access  of  air, 
enter  into  combustion  with  it,  forming  compounds  which 
have  been  designated  as  sulphurets;  but  which,  as  I  have 
stated,  ought  to  be  called  sulphides.  (686-7.)    Combustion 
also  ensues  when  the  metals  in  a  divided  state  are  heated 
with  sulphur.     The  sulphides,  formed  with  the  metals  of 
the  earths  and  alkalies,  are  soluble  in  water.     From  the 
resulting  solution  the  sulphur  is  thrown  down  by  acids. 
Like  phosphorus,  sulphur  is  susceptible  of  a  slow  as  well 
as  quick  combustion.     In  consequence  of  the  low  tempera- 
ture at  which  it  is  capable  of  becoming  converted  by  com- 
bustion into  sulphurous  acid,  sulphur  may  be  burned  out  of 
gunpowder  without  causing  it  to  flash.     If  raised  to  the 
temperature  of  369°,  it  enters  into  a  more  active  reaction. 
The  products  of  the  combustion  of  sulphur  are  sulphurous 
acid,  mingled  with  a  small  portion  of  anhydrous  sulphuric 
acid.     The  hue  of  the  flame  when  the  combustion  is  slow 
is  blue;  in  oxygen  its  flame  is  of  a  splendid  purple.     Ber- 
zelius  alleges  that  when  sulphur  is  rubbed  on  any  body,  a 
brick  for  instance,  which  has   been  previously  warmed, 
though  not  sufficiently  to  inflame  the  sulphur,  an  extremely 
feeble  blue  flame  is  produced  with  a  peculiar  odour.     This 
flame  he  conceives  to  be  the  effect  of  the  evaporation,  un- 
accompanied by  any  combustion;  "since  a  cold  body  held 
above  it  is  covered  with  the  flowers  of  sulphur  unchanged." 
This  reason,  however,  appears  insufficient;  since  the  su- 
blimation of  one  portion  of  the  sulphur  does  not  demon- 
strate that  another  is  not  oxydized,  any  more  than  the  de- 
position of  carbon  upon  a  cold  body  exposed  to  a  smoky 
flame,  proves  that  another  portion  of  carbon,  arising  from 


136 


INORGANIC  CHEMISTRY. 


the  same  source,  cannot  at  the  same  time  be  converted 
into  carbonic  acid,  as  is  known  to  be  the  fact. 

752.  Some  very  curious  anomalies  have  been  observed 
respecting  the  phenomena  of  sulphur  when  kept  over  the 
fire  after  fusion,  which  the  limits  prescribed  to  this  work 
will  not  allow  me  to  introduce.* 

Experimental  Illustrations. 

753.  Sulphur  exhibited  in  flowers  and  in  rolls;  also  crys- 
tallized as  abovementioned. 

754.  Combustion  of  Dutch  gold  leaf  and  of  an  iron  bar 
by  sulphur.     Iron  wire  converted  into  a  sulphide  by  the 
vapour  of  sulphur  emitted  in  a  jet  from  the  touch-hole  of  a 
gun  barrel,  made  red-hot  in  the,  vicinity  of  the  aperture. 

The  Combustion  of  Iron  by  a  Jet  of  Vaporized  Sulphur. 


755.  If  a  gun-barrel  be  heated  red-hot  at  the  but-end,  and  a  piece  of  sul- 
phur be  thrown  into  it,  on  closing  the  muzzle  with  a  cork,  or  blowing  into 
it,  an  ignited  jet  of  vaporized  sulphur  will  proceed  from  the  touch-hole. 
Exposed  to  this,  a  bunch  of  iron  wire  will  burn  as  if  ignited  in  oxygen  gas, 
and  will  fall  down  in  the  form  of  fused  globules,  in  the  state  of  protosul- 
phide.     Hydrate  of  potash,  exposed  to  the  jet,  fuses  into  a  sulphide  of  a  fine 
red  colour. 

756.  In  order  to  designate  the  different  proportions  of  oxygen  existing 
in  any  oxide,  relatively  to  the  other  ingredient,  I  employ  the  following  no- 
menclature in  obedience  to  the  authority  of  Thenard  and  others. 

Oxydized  body.  Oxygen.  Appellation. 

1  atom  1  atom  protoxide. 

2  atoms  1  atom  dioxide  or  suboxide. 
1  atom  2  atoms  fooxide  or  deutoxide. 

Uerzclius,  Vol.  I.  p.  250. 


SULPHUR.  137 

1  atom  3  atoms  trioxide. 

1  atom  4  atoms  g-wadroxide. 

Either  2  atoms  3  atoms  )  •     -j 

., ,  sesamoxiae. 

or  1  atom  If  $ 

757.  The  monosyllables  di,  bi>  tri,  qua,  have  an  analogous  influence 
upon  the  meaning,  when  used  before  any  other  of  the  words  employed  as 
above,  to  distinguish  the  compounds  severally  formed  by  the  basacigen  ele- 
ments, (633,)  hence  we  have  cZichloride,  proZochloride,  bichloride,  trichlo- 
ride, ^warfrichloride,  &c.     It  will  be  perceived  that  as  in  the  terms  qua- 
droxide  and  ^wadrichloride,  the  monosyllable  qua,  has  such  letters  added  as 
may  render  the  resulting  epithet  easy  to  pronounce,  and  agreeable  to  the  ear. 

758.  The  second  stage  of  combination  in  which  the  proportion  of  the 
electro-negative  ingredient  exceeds  the  ratio  of  equality,  has  been  distin- 
guished by  prefixing  the  word  deuto.     Hence  deutoxide,  deutochloride, 
deutobromide,  deutiodide.     I  prefer  ftzoxide,  as  more  precise  and  descrip- 
tive where  the  presence  of  two  atoms  is  to  be  indicated.     Per  is  prefixed  to 
signify  the  presence  of  oxygen  in  a  maximum  degree,  and  in  the  case  of 
iron,  is  used  to  designate  a  ses^moxide,  in  that  of  mercury  a  fooxide.     But 
this  monosyllable  is  also  prefixed  to  compounds  containing  any  number  of 
atoms,  whether  forming  a  base  or  an  acid.     Hence,  we  have  an  acid  dis- 
tinguished by  the  appellation  perchloric,  which  contains  seven  atoms  of 
oxygen.     The  syllables  in  question  are  prefixed  by  the  French  chemists  to 
the  words  chlorure,  bromure,  iodure,  fluorure,  cyanure,  as  they  are  by  the 
British  chemists,  prefixed  to  the  modifications  of  those  names  which  they 
employ. 

COMPOUNDS  OF  SULPHUR  WITH  OXYGEN. 

f  With  two  atoms  of  oxygen,  forms  sulphurous  acid,  equi- 
One  atom  of   .'      valent  -  -     32 

sulphur,  16,    j  With  three  atoms  of  oxygen,  forms  sulphuric  acid,  equi- 

L     valent  -     40 

f  With  two  atoms  of  oxygen,  form  hyposulphurous  acid, 
Two  atoms  of!      equivalent  -     48 

sulphur,  32,    ]  With  five  atoms  of  oxygen,  forms  hyposutphuric  acid, 

L      equivalent         x  -  -     72 

Of  Hyposulphurous  Acid. 

759.  This  acid  exists  only  in  combination  with  salifiable  bases,  and  of 
the  salts  formed  I  believe  no  useful  application  has  been  made.     Any  at- 
tempt to  explain  the  method  in  which  hyposulphites  are  produced,  will  be 
deferred  until  I  reach  the  subject  of  the  compounds  formed  by  acids  with 
metallic  oxides. 

Of  Sulphurous  Acid. 

760.  Preparation. — It  is  formed  by  the  ordinary  combustion  of  sulphur, 
or  by  boiling  sulphuric  acid  on  sulphur,  on  mercury,  or  on  any  other  sub- 
stance by  which  it  may  be  partially  deoxidized. 

761.  Properties. — Sulphurous  acid  is  a  colourless  gas,  possessing  the 
well  known  odour  of  burning  sulphur.     It  is  incapable  of  supporting  com- 
bustion, and  is  deleterious  to  life,  a  spasmodic  closure  of  the  glottis  follow- 
ing any  attempt  to  respire  it. 

762.  It  first  reddens  and  then  bleaches  litmus,  and  destroys  organic 
IS 


138 


INORGANIC  CHEMISTRY. 


colours  generally.  It  is  used  on  this  account  to  bleach  silk  and  wool.  Sul- 
phurous acid  is  soluble  in  water,  which  absorbs  43  times  its  bulk.  When 
a  solution  of  this  gas  is  exposed  to  the  air,  it  absorbs  oxygen,  and  is  con- 
verted into  sulphuric  acid.  This  acid,  with  four  times  its  bulk  of  water, 
forms  a  crystalline  hydrate,  which  melts  under  40°  j  disengaging  the 
greater  part  of  the  acid.  After  being  rendered  anhydrous  by  passing  over 
chloride  of  calcium,  sulphurous  acid  gas,  by  exposure  to  a  temperature  of 
— 12°,  condenses  into  a  colourless,  transparent  liquid,  having  the  specific 
gravity  of  1.45.  When  dropped  in  vacuo  on  the  bulb  of  a  spirit  ther- 
mometer, previously, at  50°,  and  surrounded  with  cotton,  the  intense  cold 
of —  90°  will  be  indicated.  It  is  even  said  that  alcohol  has  been  frozen 
in  this  manner.  Sulphurous  acid  gas  is  decomposed  at  a  red  heat,  either 
by  hydrogen  or  carbon.  It  is  displaced  from  its  combinations,  by  all  the 
acids  except  cyanhydric  (prussic)  and  carbonic  acid. 

Impregnation  of  Water  with  SulpMrous  Acid,  by  means  of  an  appropriate  Apparatus. 

763.  Into  the  open  neck  of  a 
tall  receiver,  a  recurved  pipe  is 
fastened,  so  as  to  descend  a  few 
inches  below  the  neck.  The 
other  end  of  the  pipe  terminates 
in  a  brass  socket,  into  which  is 
inserted  the  stem  of  an  inverted 
glass  funnel.  The  receiver  is 
placed  over  the  shelf  of  the 
pneumatic  cistern,  covered  about 
an  inch  deep  with  water,  and 
includes  a  stand  supporting  a 
tumbler  of  the  same  liquid.  A 
pipe,  extending  from  a  suction 
pump,  rises  within  the  receiver, 
nearly  as  high  as  the  stand.  If, 
under  these  circumstances,  the 
pump  be  put  into  action,  the  con- 
sequent  exhaustion  of  the  air 
from  the  receiver  causes  a  rise 
into  it  of  the  water  from  the  cis- 
tern, until  the  resistance  which 
this  water  opposes  to  a  further 
elevation  is  greater  than  that 
opposed  by  the  water  in  the 

tumbler,  to  the  entrance  of  air  from  the  recurved  pipe  communicating  with  the 
funnel.  The  air  of  the  funnel  will  then  be  drawn  into  the  receiver  through  the 
liquid  in  the  tumbler;  and  if  sulphur,  carbon,  phosphorus,  a  candle,  lamp,  or  any 
inflammable  gas  be  placed,  while  burning,  under  the  funnel,  the  fumes  may  be  made 
to  pass  through  the  water,  which  may  be  coloured  by  litmus,  or  may  contain  lime, 
ammonia,  baryta,  or  any  other  desirable  agent,  which  it  may  be  capable  of  dissolving 
or  suspending. 

Of  HyposulpJiuric  Acid. 

764.  This  acid  is  obtained  by  passing  sulphurous  acid  gas  through 
peroxide  of  manganese  suspended  in  water  in  a  finely  divided  state.  If  the 
mass  be  kept  cold,  the  peroxide  is  reduced  to  the  state  of  protoxide,  while 
the  oxygen  forms  with  the  sulphurous  acid,  hyposulphuric  acid.  This, 
with  the  protoxide,  produces  a  salt,  which,  remaining  dissolved,  may  be 
purified  by  crystallization.  By  the  addition  of  sulphide  of  barium  to  a 
solution  of  the  resulting  crystals,  the  manganense  is  precipitated  in  the 
state  of  a  sulphide,  and  hypo-sulphate  of  baryta  is  obtained.  From  this  salt 
the  hyposulphuric  acid  may  be  separated  by  sulphuric  acid,  and  concen- 
trated by  evaporation  in  vacuo,  till  it  acquires  the  specific  gravity  of  1.347. 


SULPHUR.  139 

By  heat  or  farther  concentration, -it  is  decomposed  into  sulphurous  and 
sulphuric  acid. 

765.  Hyposulphuric  acid  is  a  colourless,  inodorous  liquid,  which  reddens 
litmus,  has  an  acid  taste,  and  dissolves  zinc  with  disengagement  of  hydrogen. 

Of  Sulphuric  Acid. 

766.  Sulphuric  acid  has  been  known  since  the  close  of 
the  fifteenth  century,  when  it  was  obtained  by  Basil  Va- 
lentine by  the  distillation  of  green  vitriol,  or  sulphate  of 
iron. 

767.  Preparation. — This  acid  may  be  obtained  by  burn- 
ing sulphur  and  nitre  in  chambers  lined  with  lead,  or  by 
the  process  abovementioned,  by  which  it  was  originally 
obtained;  whence  the  almost  obsolete  name,  oil  of  vitriol. 
It  is  best  purified  by  distillation. 

768.  I  shall  defer  for  the  present  the  illustration  of  the 
process  for  procuring  sulphuric  acid  by  sulphur  and  nitre ; 
also  any  exemplification  of  its  habitudes  with  other  bodies. 

769.  Properties. — It  is  a  liquid,  oleaginous  in  its  con- 
sistency, caustic  when  concentrated,  intensely  acid  when 
dilute.     When  three  parts  are  added  to  one  of  water,  a 
boiling  heat  is  produced.  (350.)     Hot  water  explodes  with 
it  as  with  a  melted  metal.     It  is  diluted  by  the  absorption 
of  moisture  when  exposed  to  the  air.     No  acid  equals  it 
in  the  power  of  reddening  litmus.    When  pure  it  is  colour- 
less and  has  but  little  smell. 

Of  the  Sulphuric  Acid  of  Nordhausen,  and  of  Anhydrous  Sulphuric 

Acid. 

770.  The  sulphuric  acid  of  Nordhausen  differs  from  that  in  use  in  this 
country,  in  containing  a  portion  of  acid,  which  being  free  from  water,  is 
called   anhydrous.     This  anhydrous  portion  being  volatile,  assumes  the 
form  of  vapour,  and,  meeting  with  the  moisture  of  the  air,  condenses  into 
white  fume's.  (817.) 

771.  The  fuming  acid  of  Nordhausen  is  obtained  by  calcination  and  dis- 
tillation from  sulphate  of  iron,  (known  also  by  the  name  of  green  vitriol) 
contained  in  retorts  of  stone-ware.     It  may  be  obtained  also  from  white 
vitriol  or  sulphate  of  zinc  by  similar  treatment.     The  anhydrous  acid  may 
be  separated  from  the  other  portion  by  gentle  distillation,  with  the  aid  of  a 
refrigerated  receiver,  previously  well  desiccated.     It  is  a  crystalline  body 
resembling  asbestos,  and  may  be  rubbed  between  the  fingers  like  wax, 
without  their  being  attacked.     In  the  air  it  emits  thick  fumes  having  an 
acid  smell.     At  a  temperature  above  64°  it  is  liquid.     Once  congealed  it 
cannot  be  fused  without  great  care;  as  the  temperature  at  which  it  is  va- 
porized, is  but  little  above  that  at  which  it  liquefies.     Hence  it  is  apt  to 
undergo  a  sudden^enlargement  of  bulk  which  causes  it  to  be  thrown  out  of 
the  containing  vessel.    When  vaporized  it  forms  a  colourless  gas.    Neither 


140  INORGANIC  CHEMISTRY. 

in  this  state  nor  in  its  crystalline  form  has  it  any  effect  on  litmus  paper 
rendered  perfectly  dry.  When  passed  through  a  red-hot  tube  of  porcelain, 
it  is  resolved  into  oxygen  and  sulphurous  acid. 

772.  Either  caustic  lime  or  baryta  enters  into  a  species  of  combustion 
with  this  gas,  forming  with  it  a  sulphate. 

773.  The  solid  anhydrous  acid,  thrown  into  water,  produces  a  commo- 
tion resembling  the  effect  of  a  hot  iron,  and,  when  mingled  with  an  equiva- 
lent proportion  of  water,  explodes  with  a  force  sufficient  to  fracture  a  glass 
vessel. 

774.  The  fuming  acid  of  Nordhausen  is  of  use  for  the  solution  of  indigo 
employed  in  dyeing ;  as  the  anhydrous  acid  answers  better  for  this  purpose 
than  the  aqueous. 

775.  It  combines  chemically  in  four  proportions  with  water.     The  com- 
pound containing  water  in  the  least  proportion  is  formed  in  some  of  the 
processes  for  producing  the  acid  of  Nordhausen.     It  is  a  crystalline  body, 
which  probably  consists  of  2  atoms  of  anhydrous  acid  and  1  of  water. 
Four  parts  of  the  anhydrous  acid  and  about  1  of  water  form  the  concen- 
trated acid  of  the  shops,  of  the  specific  gravity  of  1.85,  which  is  considered 
to  contain  1  atom  of  water  to  1  of  acid.     When  the  acid  is  to  the  water  as 
4  to  2,  a  compound  results,  of  which  the  density  is  greater  than  the  mean 
density  of  the  constituents,  and  which  probably  consists  of  2   atoms  of 
water  to  1  of  acid.     A  similar  alteration  of  the  density  follows  the  addition 
of  water  until  the  specific  gravity  is  reduced  to  1.632. 

Of  the  Chlorides  of  Sulphur. 

776.  According  to  Thenard,  there  are  two  chlorides  which  are  both 
liquids.     One  contains  2  atoms  of  sulphur  to  1  of  chlorine ;  the  other  an 
atom  of  each  ingredient.     The  protochloride  is  a  yellow,  viscid,  oleaginous 
liquid,  heavier  than  water,  and  which  boils  at  280°.     The  other  is  reddish- 
brown,  volatile,  fuming  and  acrid,  and  boils  at  147°.     Both  are  decom- 
posed by  water,  and  alcohol. 

Of  the  Bromide  and  Iodide  of  Sulphur. 

777.  The  flowers  of  sulphur  dissolve  in  bromine,  producing  a  reddish, 
oleaginous,  fuming  liquid.     When  iodine  is  heated  gently  with  sulphur,  it 
forms  a  brilliant  crystalline  iodide,  of  a  steel-gray  colour. 

-t 


SECTION  VII. 

OF    SELENIUM. 

778.  In  1817,  Berzelius,  examining,  in  concert  with  Gahn,  the  old 
method  of  preparing  sulphuric  acid,  as  practised  at  Gripsholm,  in  Sweden, 
discovered  a  sediment  in  the  acid,  partly  red,  partly  brown,  which,  treated 
by  the  blowpipe,  produced  the  odour  of  a  rotten  radish,  and  left  a  minute 
portion  of  lead.  The  odour  thus  evolved  had  been  considered  by  Klaproth 
as  an  indication  of  tellurium.  In  consequence,  Berzelius  took  care  to  col- 
lect all  the  deposition,  produced  in  the  manufacture  of  sulphuric  acid  dur- 
ing some  months ;  no  other  sulphur  than  that  of  Fahlun  being  employed. 


SELENIUM.  141 

The  discovery  of  a  new  substance  resulted,  to  which  he  gave  the  name  of 
selenium,  from  the  Greek  word  a-g AW,  the  moon,  suggested  by  its  analogy 
with  tellurium,  named  from  tellus,  the  earth. 

779.  Selenium  seems  much  distributed  throughout  nature.     In  Sweden  it 
has  been  found  combined  sometimes  with  copper  and  silver,  sometimes  with 
copper  only.     A  small  quantity  has  been  detected  in  cubic  galena.     In 
Norway  it  has  been  discovered  united  with  tellurium  and  bismuth ;  in  the 
Hartz,  combined  with  lead,  copper,  and  mercury.     Stromeyer  has  found  it 
in  a  mineral  from  the  Lipari  islands,  combined  with  sulphur. 

780.  Preparation. — From  the  deposition  in  which  it  exists,  as  above 
stated,  selenium  is  extricated  by  solution  in  aqua  regia,  precipitation  by 
sulphuretted  hydrogen,  re-solution  in  the  same  solvent,  precipitation  by  pot- 
ash, filtration  and  evaporation  of  the  residual  liquid,  desiccation  of  the  re- 
sulting mass,  and  sublimation  with  the  addition  of  sal  ammoniac.     Selenic 
acid,  produced  by  the  reaction  of  the  selenium  with  oxygen  in  the  aqua 
regia,  is  saturated  by  the  potash,  and  afterwards  deoxidized  by  the  hydro- 
gen of  the  ammonia  in  the  sal  ammoniac  employed,  the  selenium  being 
sublimed  by  the  heat. 

781.  Properties. — Selenium,  on  cooling   after  distillation,   assumes  a 
shining  surface  of  a  deep  reddish-brown  colour,  with  a  metallic  brilliancy 
resembling  that  of  the  blood-stone  (hsernatite).     Its  fracture  is  conchoidal, 
vitreous,  of  a  lead-gray,  with  metallic  lustre.     Very  slowly  refrigerated 
after  fusion,  its  surface  becomes  granulated  and  uneven,  of  a  reddish-gray, 
and  devoid  of  lustre.     By  quick  refrigeration  the  characters  above  indicated 
result.    Selenium  has  little  tendency  to  crystallize,  yet  it  is  capable  of  sepa- 
rating in  a  crystalline  pellicle,  or  of  forming  a  crystalline  vegetation,  upon 
the  sides  of  the  vessel,  from  its  solution  in  the  state  of  a  selenhydrate. 
When  precipitated  cold  from  a  diluted  solution,  whether  by  zinc  or  sulphu- 
retted hydrogen,  it  is  red  like  cinnabar.     But  if  this  precipitate  be  boiled, 
it  turns  black  and  consolidates,  becoming  heavier.     When  pulverized,  se- 
lenium becomes  of  a  deep  red,  and  likewise  when  in  very  thin  layers. 
With  heat  it  softens,  and  at  the  boiling  point  of  water,  acquires  a  semifluid- 
ity,  becoming  completely  fluid  at  a  temperature  somewhat  higher.      In 
cooling  it  remains  soft  for  a  long  time,  and  may,  like  heated  sealing-wax, 
be  drawn  out  into  filaments.    These,  by  reflected  light,  are  gray,  with  some 
metallic  brilliancy,  but,  by  transmitted  light,  are  transparent,  and  of  a  ruby- 
red  colour. 

782.  When  selenium  is  heated  nearly  to  redness  in  a  distillatory  appa- 
ratus, it  assumes,  with  ebullition,  the  form  of  a  vapour  of  a  yellow  colour, 
deeper  than  the  hue  of  chlorine,  yet  lighter  than  that  of  sulphur.     This 
vapour  condenses  in  the  neck  of  a  retort  in  black  drops,  which  coalesce  like 
those  which  are  formed  by  the  condensation  of  mercury.    When  condensed 
with  access  of  air,  selenium  appears  like  a  red  fume,  and  is  deposited  in  a 
state  analogous  to  the  flowers  of  sulphur,  but  of  a  cinnabar-red  colour. 
The  smell  of  a  radish  is  only  perceived  when  the  heat  is  sufficient  to  be 
productive  of  oxidation.     The  specific  gravity  of  selenium  is  from  4.3,  to 
4.32. 

Compounds  of  Selenium  with  Oxygen. 

7§3.  Selenium  has  but  a  feeble  affinity  for  oxygen,  yet  forms  a  volatile 
oxide,  which  has  the  smell  either  of  radish  or  decayed  radish.  It  forms 
also  two  acids,  the  selenious  and  selenic.  The  latter  of  these  is  isomor- 
phous  with  sulphuric  acid.  (474.) 


142  INORGANIC  CHEMISTRY. 

784.  Selenious  acid  is  procured  by  the  combustion  of  selenium  in  oxy- 
gen gas,  or  by  reaction  with  nitric,  or  nitromuriatic  acid. 

785.  Selenic  acid  is  obtained  by  the  deflagration  of  nitre  with  selenium 
in  a  hot  crucible;  a  seleniate  of  potash  results,  which  is  decomposed  by 
nitrate  of  lead,  and  the  resulting  seleniate  of  lead  is  decomposed  by  sul- 
phuretted hydrogen.     The  sulphuret  of  lead  precipitates,  while  selenic  acid 
is  dissolved  in  the  water  employed.    When  heated  to  280  degrees,  it  attains 
its  highest  concentration,  and  at  290  degrees  is  decomposed  into  oxygen 
and  selenious  acid. 

786.  The  highest  specific  gravity  of  selenic  acid   is  2.6.     It  resembles 
sulphuric  acid  in  its  consistency,  in  its  evolving  heat  by  dilution  with  water, 
and  in  the  power  of  dissolving  iron  and  zinc,  with  the  evolution  of  hydro- 
gen.    It  cannot  be  rendered  anhydrous.     When  its  density  is  at  the  maxi- 
mum, it  contains  16  per  cent,  of  water.     With  the  aid  of  heat,  it  oxidizes 
and  dissolves  copper  and  even  gold,  but  not  platinum.     With  chlorohydric 
acid,  it  constitutes  a  sort  of  aqua  regia,  which  dissolves  both  gold  and  pla- 
tinum.    Its  salts  cannot  be  distinguished  from  the  sulphates,  unless  by  the 
property  of  detonating  with  carbon  at  a  red  heat,  and  that  of  causing  an 
evolution  of  chlorine,  when  boiled  with  muriatic  acid.     Selenic  acid  may 
be  separated  from  sulphuric  acid  by  saturation  with  potash,  and  ignition 
with  sal  ammoniac.     The  selenic  acid  is  decomposed  into  selenium  by  the 
hydrogen  of  the  ammonia. 

787.  Selenium  combines  with  chlorine  and  bromine,  and  with  sulphur  in 
every  proportion. 

788.  As  there  is  not  one  of  the  metals  which  have  decided  pretensions  to 
the  metallic  character,  which  is  not  an  excellent  conductor  of  both  heat  and 
electricity,  and  as  metallic  brilliancy  is  another  striking  attribute  of  the 
metallic  genus,  I  cannot  understand  wherefore  selenium,  which  is  admitted  to 
be  destitute  of  the  two  first  mentioned  characteristics,  and  to  possess  the  last 
imperfectly,  should  be  received  into  the  class  of  metals  ;    while  carbon, 
which  in  the  form  of  plumbago,  is  endowed  with  them  all,  is  excluded.     I 
can  not  'consider  selenium  as  a  metal.     It  is  stated  to  have  the  brilliancy  of 
haematite,  which  is,  I  conceive,  inferior  in  that  respect  to  plumbago,  which 
Berzelius  considers  as  pure  carbon. 


SECTION  VIII. 

OF   TELLURIUM. 

789.  A  metal  has  been  found  in  the  veins  of  auriferous  silver  in  the 
mines  of  Transylvania,  which  has  been  called  tellurium.     It  is  found  also 
in  small  quantities  in  Norway,  united  to  selenium.    Tellurium  has  likewise 
been  discovered  in  Connecticut.     It  is  found  chiefly  in  the  state  of  an  alloy 
with  gold  and  silver. 

790.  Tellurium  displays  a  metallic  brilliancy,  and  is  of  a  colour  between 
that  of  tin  and  antimony,  and  of  a  lamellated  structure.     WThen  melted  in 
a  glass  vessel,  replete  with  hydrogen,  and  slowly  cooled,  it  assumes  the  ap- 
pearance of  burnished  silver.     Fused  in  a  vessel,  it  presents  crystals  of  a 
determinable  form.     It  fuses  below  a  red-heat,  and  above  that  temperature 
is  volatilized.     When  heated  before  the  blowpipe,  it  takes  fire,  and  burns 
with  a  blue  flame  bordering  on  green,  and  is  dissipated  in  gray  pungent 


HYDROGEN.  143 

fumes,  which  have  sometimes  the  smell  of  horse-radish.  This  smell  is  as- 
cribed by  Berzelius  to  the  presence  of  selenium.  Latterly  the  same  author 
assumes  its  specific  gravity  to  be  6.2324. 

791.  Tellurium  may  be  oxidized  cither  by  combustion  or  by  nitric  acid. 
The  oxide,  exposed  before  the  blowpipe  upon  charcoal,  is  decomposed  with 
explosive  violence. 

792.  Berzelius  alleges  that  tellurium  will  dissolve  in  concentrated  sul- 
phuric acid  without  being  oxidized,  in  which  it  differs  from  other  metals. 
I  infer  that  it  forms  a  soluble  oxysulphide.     The  colour  of  the  resulting 
solution  is  purplish-red.     Tellurium  is  more  especially  entitled  to  our  no- 
tice on  account  of  its  great  analogy  to  sulphur  and  selenium,  and  of  its 
forming  both  acids  and  bases,  which  uniting,  form  telluri-salts.     It  is  upon 
this  ground  that  Berzelius  included  it  in  his  amphigen  class,  and  that  I  con- 
sequently place  it  among  the  basacigen  bodies. 


—»*«©«««••— 

OF  RADICALS. 

793.  Radicals  are  bodies  capable  of  forming  with  a  ba- 
sacigen body  either  an  acid  or  a  base,  and  are  divided  into 
those  which  are  metallic,  and  those  which  are  non-metallic. 
(633.) 

OF  NON-METALLIC  RADICALS. 
The  bodies  which  I  place  under  this  head  are: — 

Hydrogen,  Boron, 

Nitrogen,  Silicon, 

Phosphorus,  Zirconion. 
Carbon, 

SECTION  I. 

OF   HYDROGEN. 

794.  In  its  gaseous  state,  it  is  the  principal  constituent 
of  all  ordinary  flame.     It  is  an  ingredient  in  water,  and 
combined  with  oxygen  and  carbon,  it  is  found  in  all  ve- 
getable and  animal  substances.     It  derives  its  name  from 
vfy,  water,  and  y/va^i,  to  produce. 

795.  Preparation. —  Per  se,  hydrogen  exists  only  in  the 
gaseous  state.     In  this  form  it  may  be  obtained  by  the  re- 
action of  diluted  sulphuric  or  muriatic  acid  with  zinc  or 
iron,  or  of  steam  with  iron  turnings,  made  red-hot  in  a  gun 
barrel.     It  may  be  evolved  in  a  state  of  purity,  and  con- 


144      -  INORGANIC    CHEMISTRY. 

sequently  destitute  of  odour,  from  pure  water,  by  Voltaic 
agency,  or  by  reaction  with  an  amalgam  of  potassium. 

Self -regulating  Reservoir  for  Hydrogen  and  other  Gases. 

796.  The  following  figure  represents  a  self-regulating  reservoir  for  hy- 
drogen gas. 

797.  This  very  perspicuous 
engraving  can  require  but  lit- 
tle explanation.  Suppose  the 
glass  jar  without  to  contain  di- 
luted sulphuric  acid;  the  in- 
verted bell,  within  the  jar,  to 
contain  some  zinc,  supported 
on  a  tray  of  copper,  suspended 
by  wires  of  the  same  metal 
from  the  neck  of  the  bell.  The 
cock  being  open  when  the  bell 
is  lowered  into  the  position  in 
which  it  is  represented,  the  at- 
mospheric air  will  escape,  and 
the  acid,  entering  the  cavity  of 
the  bell,  will,  by  its  reaction 
with  the  zinc,  cause  hydrogen 
gas  to  be  copiously  evolved. 
As  soon  as  the  cock  is  closed, 
the  hydrogen  expels  the  acid 
from  the  cavity  of  the  bell; 
and,  consequently,  its  reaction  with  the  zinc  is  prevented,  until  another  por- 
tion of  the  gas  be  withdrawn.  As  soon  as  this  is  done,  the  acid  re-enters 
the  cavity  of  the  bell,  and  the  evolution  of  hydrogen  is  renewed  and  con- 
tinued, until  again  arrested,  as  in  the  first  instance,  by  preventing  the  escape 
of  the  gas,  and  consequently  causing  it  to  displace  the  acid  from  the  inte- 
rior of  the  bell,  within  which  the  zinc  is  suspended.* 

798.  By  means  of  apparatus  of  this  kind,  I  have  been  enabled  to  have 
self-regulating  reservoirs  of  nitric  oxide,  of  sulphydric  acid,  of  carbonic 
acid,  of  chlorine,  and  of  chlorohydric  acid,  merely  by  changing  the  ma- 
terials, and  making  such  a  modification  of  the  means  of  supporting  them 
as  the  agents  employed  or  evolved  require. 


*  The  principle  of  this  apparatus  is  analogous  to  that  which  was  contrived  by 
Gay-Lussac.  I  had  employed  the  same  principle,  however,  when  at  Williamsburg, 
to  moderate  the  evolution  of  carbonic  acid,  before  I  had  read  of  Gay-Lussac's  appa- 
ratus. I  prefer  the  modification  above  described.  In  the  first  place,  it  is  internally 
more  easy  of  access  for  the  purpose  of  cleansing ;  secondly,  it  is  much  better  quali- 
fied for  containing  sulphuret  of  iron,  or  marble,  for  generating  sulphuretted  hydro- 
gen, or  carbonic  acid  gas:  and  thirdly,  by  raising  the  bell  glass,  until  the  liquid 
within  and  without  is  on  a  level,  the  pressure  may  be  removed. 

In  the  other  form,  the  pressure  on  the  gas  is  so  great,  that,  unless  the  tube,  the 
cock,  and  the  junctures  be  perfectly  tight,  there  must  be  a  considerable  loss  of  mate- 
rials ;  since  the  escape  of  gas  inevitably  causes  their  consumption,  by  permitting  the 
acid  to  reach  the  zinc,  or  other  material  employed. 


HYDROGEN. 


145 


Large  Self-regulating  Reservoir  for  Hydrogen. 
V 


799.  This  figure  represents  a 
self-regulating  reservoir  for  hy- 
drogen, constructed  like  that  de- 
scribed in  the  preceding  article; 
excepting  that  it  is  about  fifty 
times  larger,  and  is  made  of  lead, 
instead  of  glass.  This  reservoir 
may  be  used  in  all  experiments 
requiring  a  copious  supply  of 
hydrogen.  When  gas  is  to  be 
supplied  to  the  hydro-oxygen,  or 
compound  blowpipe,  the  perfo- 
rated knob  at  the  end  of  the  pipe, 
which  has  an  orifice  on  one  side, 
is  placed  under  the  gallows,  G, 
(seen  in  the  fig.  of  the  compound 
blowpipe,  331)  and  fastened  air- 
tight to  the  pipe  of  that  instru- 
ment, by  the  pressure  of  the 
screw  of  the  gallows.  The  gas 
is  retained,  or  allowed  to  flow 
through  the  pipe,  by  means  of 
the  valve  cock,  V,  which  is  much 
less  liable  to  leak,  than  one  of 
the  common  form. 


800.  Properties  of  Hydrogen. — It  is  the  lightest  of  all 
ponderable  substances.     One  hundred  cubic  inches  weigh 
only  2.13  grains.     Its  weight  to  that  of  oxygen  is  as  1  to 
16.     Its  specific  gravity,  the  gravity  of  air  being  assumed 
as  1,  is  0.0689.     It  is  about  200,000  times  lighter  than 
mercury,  and  300,000  times  lighter  than  platinum.     In  its 
ordinary  state  it  smells  unpleasantly.     When  pure  it  is 
without  odour.     In  its  nascent  state,  as  when  liberated 
by  means  of  an  acid,  it  is  extremely  prone  to  take  up  a 
minute  portion  of  sulphur,  phosphorus,  arsenic,  or  of  some 
other  metals.    Of  the  last  mentioned  property,  a  most  use- 
ful application  is  now  made,  which  I  shall  mention  when 
treating  of  the  process  for  detecting  arsenic. 

801.  The  respiration  of  hydrogen,  mixed  with  the  same 
proportion  of  oxygen  as  exists  in  atmospheric  air,  is  not 
attended  by  any  oppressive  sensations;  yet  a  profound 
sleep  is  said  to  have  been  induced  in  animals  surrounded 

19 


146  INORGANIC  CHEMISTRY. 

by  such  a  mixture.  When  breathed  either  in  this  way  or 
unmixed,  it  will  be  found  to  produce  a  ludicrous  alteration 
in  a  man's  voice,  making  it  shrill  and  puerile,  and  so  out 
of  character  as  not  to  be  recognised.  Sound  is  said  to 
move  in  this  gas  with  a  velocity  three  times  as  great 
as  in  the  atmosphere.  According  to  the  experiments  of 
Leslie,  the  sound  of  a  clock  bell  was  as  feeble  in  hydrogen 
as  in  air  rarefied  one  hundred  times.  By  no  degree  of 
pressure  which  has  been  tried,  can  hydrogen  be  condensed 
into  a  liquid.  In  consequence  of  its  levity,  it  escapes 
rapidly  from  an  open  vessel,  unless  inverted.  It  is  pre- 
eminently inflammable,  yet  a  taper  when  immersed  in  it  is 
extinguished.  A  jet  of  it,  ignited,  appears  like  a  feebly 
luminous  candle  flame,  and,  if  surrounded  by  a  glass  tube, 
produces  a  remarkable  sound. 

802.  It  has  been  stated  that  for  equal  volumes,  all  gases 
have  the  same  capacity  for  heat;  it  follows,  that  for  equal 
weights,  the  capacities  must  be  inversely  as  their  specific 
gravities  or  their  densities.     Hence  hydrogen  having  the 
lowest  specific  gravity,  will  have  the  highest  specific  heat. 
(257.)    It  is  in  fact  calculated  to  be  as  to  that  of  an  equal 
weight  of  air  as  13.08  is  to  1,  and  to  that  of  an  equal 
weight  of  water  as  3.88  to  1.     Its  refracting  power  is  ten 
and  a  half  times  greater  than  that  of  the  atmosphere. 

803.  When  mixed  with  oxygen  or  atmospheric  air,  and 
subjected  to  flame,  an  electric  spark,  or  a  wire  ignited  by 
galvanism,  it  explodes.    With  chlorine  it  explodes  under 
like  circumstances,  and  likewise  in  the  solar  rays.     In 
burning,  it  disengages  sufficient  heat  to  melt  315  times 
its  weight  of  ice.     Dobereiner  discovered  that  platinum 
sponge,  a  cold  metallic  congeries,  becomes  ignited  on  en- 
tering a  mixture  of  hydrogen  with  oxygen  gas,  and  causes 
it  to  inflame  by  an  agency  which  has  not  been  satisfacto- 
rily elucidated.     It  has  since  been  discovered  that  palla- 
dium, rhodium,  and  iridium  possess  this  property  in  nearly 
the   same  degree.     I  have  ascertained  that  if  asbestos, 
charcoal,  or  clay  be  soaked  in  chloride  of  platinum,  and 
afterwards  desiccated  and  heated  red-hot,  the  property  of 
inflaming  a  mixture  of  hydrogen  and  oxygen  is  acquired. 

Experimental  Illustrations  of  the  Properties  of  Hydrogen. 

804.  Levity  of  the  gas  demonstrated  by  the  ascension 
of  a  balloon,  or  by  the  effect  of  filling  with  hydrogen,  a 


HYDROGEN. 


147 


glass  globe  balanced  upon  a  scale  beam.  (71,  &c.)  Effect 
upon  the  voice  shown.  Inflammation  of  a  gaseous  mix- 
ture of  hydrogen  with  atmospheric  air  by  platinated  asbes- 
tos, or  platinum  sponge.  Apparatus  for  lighting  a  candle 
by  a  jet  of  hydrogen  from  a  self-regulating  reservoir,  either 
by  the  electric  spark  or  platinum.  (327.)  A  mixture  of 
hydrogen  and  oxygen,  ignited  within  a  small  cannon,  ex- 
plodes. 


Candle  extinguished  and  re-lighted  by  Hydrogen. 

805.  If  a  lighted  candle  be  introduced  into  a  wide- 
mouthed  inverted  phial,  filled  with  hydrogen  gas,  the 
flame  of  the  candle  will  be  extinguished  from  the  want 
of  oxygen.  Meanwhile,  at  the  mouth  of  the  bottle, 
where  there  is  a  sufficient  access  of  air,  the  gas  will 
have  taken  fire,  and  will  burn  with  a  lambent  flame 
scarcely  visible  in  daylight.  Hence  if  the  candle  be 
slowly  withdrawn,  it  will  be  re-lighted  as  it  passes 
through  the  flame. 


Philosophical  Candle. 

806.  Small  pieces  of  zinc  or  iron,  being 
introduced  into  a  glass  flask,  so  as  to  occu- 
py about  one-eighth  of  its  capacity,  pro- 
vide a  suitable  cork,    so  perforated  as   to 
receive  a  glass  tube  terminating  in  an  ori- 
fice just  large  enough  to  admit  a  common 
brass  pin.    ,Pour  upon  the  zinc  five  parts 
of  water,  and    adding    one    of   sulphuric 
acid,    fasten   the   cork,   with    its    tube    in- 
serted, into  the  mouth  of  the  flask.     After 
all  the  atmospheric  air  has  escaped  from 
the  vessel,  on  applying  the  flame  of  a  can- 
dle to  the  orifice  of  the  tube,  it  will  be  sur- 
mounted by  an  inflamed  jet  of  hydrogen, 
which   has   been   called   the   philosophical 
candle. 

807.  The  light  given  out  by  the  flame  of 
pure  hydrogen,  is,  nevertheless,  wholly  in- 
competent to  answer  the  purpose  of  candle 
light;  but  I  have  ascertained,  that  the  addi- 
tion of  a  small  quantity  of  spirit  of  turpen- 
tine to  the  materials  obviates  this  defect. 


148  INORGANIC  CHEMISTRY. 

Application  of  Hydrogen  and  Oxygen  in  Eudiometry. 

808.  The  explosive  union  of  hydrogen  with  oxygen  has 
been  much  resorted  to  in  the  analysis  of  gaseous  mixtures 
containing  either.    For  this  purpose  a  stout  tube,  sealed  at 
one  end,  at  the  other  shaped  like  a  trumpet,  has  holes 
drilled  into  it,  near  the  sealed  end,  for  the  introduction  of 
metallic  wires,  the  ends  of  which  approach  near  enough  to 
each  other  within  the  tube,  for  the  passage  of  an  electric 
spark.     A  known  volume  of  the  explosive  mixture  being 
introduced  into  the  tube,  and  ignited  by  a  spark  from  an 
electrophorus  or  an  electrical  machine,  and  the  residual  air 
being  transferred  to  a  graduated  tube,  the  deficit  caused 
by  the  process  is  ascertained. 

809.  The  glass  tube,  employed  in  this  experiment,  with 
its  appurtenances,  is  called  a  eudiometer.  This  appellation 
was  at  first  applied  to  the  instruments  used  in  the  analy- 
sis of  atmospheric  air,  of  which  one-fifth  part  is  oxygen 
gas ;  but  it  has  since  been  applied  to  all  instruments,  em- 
ployed  in   measuring   the   results   of  pneumato-chemical 
analysis.     I  subjoin  an  engraving  descriptive  of  the  eudio- 
meter of  the  celebrated  Volta. 

Volta's'^Eudiometer. 

810.  The  eudiometer  represented  by  this  figure,  (see  next  page)  was  contrived 
by  Volta,  for  the  analysis  of  gaseous  mixtures  and  compounds  containing  oxygen  or 
hydrogen. 

811.  The  body  of  this  instrument,  A,  is  a  cylinder  of  glass,  which  is  cemented  below 
into  a  brass  socket,  united  by  a  screw  with  the  cock,  B.     This  cock  screws  into  a 
hollow  brass  pedestal,  C,  with  the  cavity  in  which  the  bore  of  the  cock  communi- 
cates.    The  glass  cylinder  is  also  cemented  into  a  cap,  D,  which  is  surmounted  by 
a  cock,  E,  supporting  the  basin,  F.     The  cavity  of  the  basin  communicates,  through 
the  bore  of  the  cock  when  open,  with  that  of  the  cylinder.     Into  the  perforation  in 
the  bottom  of  the  basin,  the  sealed  tube,  G,  graduated  into  200  parts,  fastens  by  a 
screw  cut  upon  a  socket,  into  which  the  tube  is  cemented.     On  one  side  of  the  cy- 
linder, there  is  a  metallic  scale,  h,  each  division  of  which  indicates  a  section  of  the 
bore  of  the  cylinder  equivalent  to  ten  degrees  on  the  tube.     I,  is  an  insulated  wire 
for  passing  the  electric  spark  through  any  explosive  mixture  which  may  be  intro- 
duced into  the  cylinder.     A;,  is  a  measure  which  holds  as  much  gas  as,  when  admit- 
ted into  the  cylinder,  would  be  equal  to  ten  divisions  of  the  metallic  scale,  or  to 
100  degrees,  if  allowed  to  rise  into  the  tube.     This  measure  is  furnished  with  a 
slide,  in  which  a  hole  is  represented  at  I.    The  measure  is  open  when  this  hole  is 
within  it;  it  is  closed  when  the  hole  is  outside,  as  it  appears  in  the  engraving.     By 
this  mechanism  it  is  rendered  certain  that,  with  care,  the  volume  of  air,  taken  at 
one  time,  will  be  equal  to  that  taken  at  another. 

812.  In  order  to  put  this  eudiometer  into  operation,  open  both  the  cocks,  and  depress 
it  in  the  water  of  the  cistern,  until  the  water  rises  into  the  cylinder  just  above  the 
lower  cock.     This  cock  is  then  to  be  closed,  and  the  pedestal  placed  on  the  shelf 
of  the  cistern.     Water  is  to  be  poured  into  the  basin,  until  both  the  basin  and  cy- 
linder are  full.     The  glass  tube,  G,  is  then  to  be  filled  with  water  and  inverted: 
and  the  orifice,  meanwhile  closed  with  the  finger,  is  to  be  depressed  below  the» sur- 
face of  the  water  in  the  basin,  without  admitting  air.     The  tube  is  then  screwed 
into  its  place,  so  as  to  occupy  the  position  in  which  it  appears  in  the  figure. 

813.  The  upper  cock  being  closed,  let  the  measure,  k,  be  plunged  in  the  water  of  the 


Volumescope. 


(Page  149.) 


HYDROGEN. 


149 


cistern,  the  orifice  open  for  the  air  to  escape.    Then  invert  it,  the  orifice  being  kept 

under  the  surface  of  the  water.  Next  fill  it  with 
the  mixture  to  be  analyzed,  as  for  instance  a  mix- 
ture of  equal  volumes  of  hydrogen  and  atmos- 
pheric air.  Shut  the  orifice  by  moving  the  slide, 
allow  any  excess  of  air  to  escape,  and  then, 
placing  the  orifice  of  the  measure  under  the 
pedestal  of  the  eudiometer,  open  the  orifice :  the 
gaseous  mixture  will  mount  into  the  cavity  of  the 
cylinder.  Shut  the  lower  cock,  and  pass  an  elec- 
tric spark  through  the  included  mixture.  An 
explosion  will  ensue,  and  consequently  a  portion 
of  the  mixture  will  be  condensed  into  water.  By 
opening  the  cock,  B,  the  deficit,  thus  produced, 
will  be  compensated  by  the  entrance  of  an  equi- 
valent bulk  of  water.  Open  the  upper  cock,  and 
allow  the  residual  gas  to  mount  into  the  gra- 
duated tube.  Detach  this  tube  from  the  eudio- 
meter, and  closing  the  orifice  with  the  finger 
under  water,  before  lifting  it  from  the  basin,  sink 
it  in  water,  until  this  liquid  be  as  high  without  as 
within  the  tube.  It  may  now  be  seen  how  far 
the  residual  air  falls  short  of  the  100  measures 
introduced. 

814.  It  must  be  evident  that  we  might  operate 
on  double  the  quantity  of  gas,  by  taking  the  mea- 
sure full  of  it  twice  instead  of  once;  and  that  a 
mixture  of  two  volumes  of  air  and  one  volume  of 
hydrogen  might  be   analyzed,  by  taking  three 
measures  equivalent  to  300  parts.     The  loss  by 
the  explosion  would  be  the  number  of  degrees 
that  the  residue  would  fall  short  of  300,  when  in 
the  graduated  tube. 

815.  A  mixture  of  three  volumes  of  hydrogen 
with  one  of  impure  oxygen  might  be  analyzed  by 
taking  the  measure  twice  full,  which  is  the  same 
as  200  parts.     In  this  case,  one-third  of  the  deficit 
would  be  the  quantity  of  pure  oxygen  in  £  of 
200,  or  50  parts,  of  the  impure  gas. 

816.  The  metallic  scale  accompanying  the  cylin- 
der I  have  never  used.   Since  one  of  its  divisions  is 
equivalent  to  ten  of  those  on  the  tube,  observa- 
tions made  by  means  of  the  latter  must  be  ten 
times  more  accurate. 

817.  Instead  of  resorting  to  an  electric  spark  to 
produce  the  inflammation  of  the  gases,  I  have 

added  to  this  eudiometer  a  galvano-ignition  apparatus,  (335,)  by  means  of  which  a 
gaseous  mixture  may  at  any  time  be  ignited  with  certainty. 

Of  the  Volumescope. 

818.  In  experiments  performed  with  such  eudiometers  as  are  mentioned  above, 
the  steps  of  the  process  cannot  be  made  evident  to  a  numerous  class,  so  as  to  ena- 
ble them  to  judge  of  the  result  by  inspection.  In  order  to  attain  this  object,  I  have 
contrived  the  apparatus  represented  on  the  opposite  page,  which  I  have  called  a 
volumescope,  as  I  find  it  very  inconvenient  not  to  have  a  name  for  every  variety  of 
apparatus.  It  consists  of  a  very  stout  glass  tube,  of  30  inches  in  height,  and  taper- 
ing in  diameter  inside  from  2  and  £th  to  1  and  £th  inches.  The  least  thickness  of 
the  glass  is  at  the  lower  end,  and  is  there  about  fths  of  an  inch.  There  is  an  obvious 
increase  in  thickness  towards  the  top,  within  the  space  of  about  C  inches.  The  tube 
is  situated  between  the  iron  rods,  I  I,  which  are  riveted,  at  their  lower  ends,  to  a 
circular  plate  of  the  same  metal,  let  into  the  lower  surface  of  a  square  piece  of  plank, 
P.  This  piece  of  plank  supports  the  tube,  so  as  to  be  concentric  with  an  aperture 
corresponding  with  the  bore  of  the  tube,  and  constituting  effectively  its  lower  ori- 
fice. The  upper  orifice  of  the  tube  is  closed  by  a  stout  block  of  mahogany,  which 
receives  a  disk  of  gum  elastic  in  a  corresponding  hollow,  made  by  means  of  a  lathe, 
so  as  to  be  of  the  same  diameter  as  the  end  of  the  tube.  Into  a  perforation  in  the 


150  INORGANIC  CHEMISTRY. 

centre  of  the  mahogany  block,  communicating  with 'the  bore  of  the  tube,  a  cock,  c, 
furnished  with  a  gallows  screw,  is  inserted.  Through  the  block,  on  each  side  of  the 
perforation,  wires  are  introduced,  so  as  to  be  air-tight.  To  the  outer  ends  of  these 
wires  two  gallows  screws,  g  g,  are  soldered  ;  'to  the  inner  ends  a  platinum  wire,  so 
as  to  form  a  galvano-ignition  apparatus.  (335.) 

819.  The  apparatus  being  thus  constructed,  le,t  it  be  firmly  fixed  over  the  pneumatic 
cistern,  so  that  the  water  may  rise  about  an  inch  above  the  lower  extremity  of  the 
tube.     To  the  gallows  screws,  g  g,  attach  two  leaden  rods,  severally  proceeding 
from  the  poles  of  a  calorimotor.     By  means  of  a  leaden  pipe,  produce  a  communi- 
cation between  the  bore  of  the  cock  and  an  air  pump,  so  that  by  pumping  the  air 
from  the  cavity  of  the  tube,  the  water  of  the  cistern  may  be  made  to  rise  into  the 
space  thus  exhausted  of  air.     On  each  side  of  the  tube,  and  between  it  and  each 
iron  rod,  there  are  two  strips  of  wood  S  S,  scored  so  as  to  graduate  about  seven 
inches  of  the  tube  into  eight  parts.     The  various  distances  between  these  gradua- 
tions were  ascertained  by  introducing  into  the  tube,  previously  filled  with  water, 
exactly  the  same  bulk  of  air  eight  times,  and  marking  the  height  of  the  water  after 
each  addition.    By  these  means  the  instrument  is  graduated  into  eight  parts  of  equal 
capacity ;  and  we  are  by  aid  of  it  enabled  to  measure  the  ga§es,  and  to  notice  the 
diminution  of  volume  resulting  from  their  spontaneous  reaction,  or  that  which  may 
be  induced  by  the  ignition  of  the  wire. 

820.  The  volumescope  being  so  far  prepared,  and  the  tube  exhausted  of  air  so  as  to 
become  full  of  water,  close  the  cock  leading  to  the  air  pump,  and  introduce  two 
volumes  of  pure  hydrogen  and  one  volume  of  pure  oxygen,  which  may  be  most  con- 
veniently and  accurately  effected  by  the  sliding-rod  gas  measure.     The  plates  of  the 
calorimotor  being  in  the  next  place  excited  by  the  acid,  the  ignition  of  the  platinum 
wire  ensues,  and  causes  the  hydrogen  and  oxygen  to  explode.     When  they  are  pure, 
the  subsequent  condensation  is  so  complete,  that  the  water  will  produce  a  concus- 
sion as  it  rises  forcibly  against  the  gum  elastic  disk,  which,  aided  by  the  mahogany 
block,  closes  the  upper  orifice  of  the  tube. 

821.  If  the  preceding  experiment  be  repeated  with  an  excess  of  either  gas,  it  will  be 
found  that  a  quantity,  equal  to  the  excess,  will  remain  after  the  explosion.     This  is 
very  evident  when  the  excess  is  just  equal  to  one  volume,  because,  in  that  case,  just 
one  volume  will  remain  uncondensed.     By  these  means,  a  satisfactory  illustration  is 
afforded  of  the  simple  and  invariable  ratio  in  which  the  gaseous  elements  of  water 
unite,  when  mixed  and  inflamed ;  which  is  a  fact  of  great  importance  to  the  atomic 
theory,  and  to  the  interesting  theory  of  volumes  which  hereafter  I  shall  have  oc- 
casion to  notice. 

822.  Since  the  accompanying  engraving  was  made,  a  plate  of  brass,  about  a  half 
an  inch  in  thickness,  has  been  substituted  for  the  mahogany  block.     This  plate  was 
made  true  by  means  of  the  slide  lathe,  the  holes  for  the  cocks  entering  upon  the 
side,  and  extending  inwards  and  downwards,  so  as  to  open  into  the  bore  of  the  tube, 
when  the  plate  is  in  its  place. 

823.  It  has  been  found  to  contribute  much  to  convenience  in  manipulating  with 
this  instrument,  to  have  a  vessel,  an  iron  mercury  bottle,  for  instance,  such  as  re- 
presented in  page  69,  (398,)  interposed  between  the  air  pump  employed,  and  the 
volumescope,  so  as  to  be  exhausted  before  performing  an  experiment.     Thus  as- 
sisted, in  order  to  cause  the  tube  to  be  filled  with  water,  it  is  only  necessary  to  turn 
the  key  of  the  proper  cock.     Moreover,  by  this  expedient,  the  water  is  prevented 
from  reaching  the  pump,  and  when  corrosive  vapours  are  produced,  lessens  the 
danger  of  their  injuring  the  mechanism  of  that  instrument. 

COMPOUNDS  OF  HYDROGEN  WITH  OXYGEN. 
Of  Water. 

824.  This  liquid  may  be  produced  by  the  combustion  of 
hydrogen  gas  with  oxygen .  gas.     It  may  be  decomposed 
by  passing  it  in  steam  over  iron,  ignited  in  a  gun  barrel ; 
also  by  the  aid  of  acids,  by  the  alkaline  metals,  by  sul- 
phurets  and  phosphurets,  by  electricity,  by  galvanism,  and 
by  vegetable  leaves. 

825.  Water  is  necessary  to  some  crystals  and  to  gal- 


HYDROGEN. 


151 


vanic  processes.     Its  powers  as  a  solvent  are  peculiarly 
extensive,  and  are  increased  by  heat  and  pressure. 

826.  Water  is  one,  among  other  substances,  which  acts 
as  an  acid  with  powerful  bases,  while  with  powerful  acids 
its  acts  as  a  base.     Berzelius,  in  some  instances,  calls  it 
hydric  acid.     It  will  be  seen,  as  we  proceed,  that  it  com- 
bines with  various  metallic  oxides,  especially  those  which 
constitute  the  alkalies  and  alkaline  earths.     With  the  lat- 
ter especially  it  produces  much  heat  in  combining,  as  ex- 
emplified in  the  slaking  of  lime ;  and  in  several  of  its  com- 
binations with  them,  its  affinity  is  too  energetic  to  be 
overcome  by  any  degree  of  heat.     Excepting  acids,  any 
compound  in  which  water  exists  as  an  essential  constituent, 
is  called  a  hydrate.     Thus  slaked  lime  is  a  hydrate  of 
lime ;  but  this  term  is  inappropriate,  when  applied  to  the 
compounds  which  it  forms  with  acids.     To  them  the  term 
aqueous  is  applied  by  Berzelius.     The  absence  of  water -in 
any  substance  in  which  it  is  liable  to  be  present,  is  signi- 
fied by  the  word  anhydrous.     I  infer  then  that  its  presence 
should  be  indicated  by  means  of  the  adjective  hydrous. 
The  vaporization   and  evaporation  of  water  has,  I  trust, 
been  sufficiently  illustrated.  (177,  229,  234.)    As  a  moving 
power  for  machinery,  as  the  source  of  rain,  and  as  the 
cause  of  earthquakes,  aqueous  vapour  is,  obviously,  for 
good  or  for  evil,  one  of  the  most  potent  agents  of  nature. 

The  equivalent  of  oxygen  being         8 
And  that  of  hydrogen  1 

Water  is  represented  by  9 

Experimental  Illustrations  of  the  Agency  of  Water. 

827.  No  reaction  ensues  between  tartaric  acid  and  car- 
bonated alkali  until  water  is  added,  when  a  lively  efferves- 
cence ensues. 

828.  Concentrated  sulphuric  acid  and  zinc  remain  inac- 
tive until  water  is  added,  when  a  copious  evolution  of 
hydrogen  follows. 

829.  If  nitrate  of  copper  be  rolled  up  in  tin  foil  without 
moisture,  the  mass  will  remain  inert;  but  if  moistened 
before  it  is  rolled  up,  ignition  will  be  produced. 


152  INORGANIC  CHEMISTRY. 

Aqueous  Vapour  or  Steam  decomposed  by  ignited  Iron. 


830.  Having  introduced  some  turnings  of  iron  or  refuse 
card  teeth  into  an  old  musket  barrel,  lute  into  one  end  of 
it  the  beak  of  a  half-pint  glass  retort,  about  half  full  of 
water;  into  the  other  end,  a  flexible  leaden  tube.    Lift  the 
cover  off  the  furnace,  and  place  the  barrel  across  it,  so 
that  the  part  containing  the  iron  turnings  may  be  exposed 
to  the  greatest  heat.     Throw  into  the  furnace  a  mixture 
of  charcoal  and  live  coals.     The  barrel  will  soon  become 
white-hot.     In  the  interim,  by  means  of  a  chauffer  of 
coals,  the  water  being  heated  to  ebullition,  the  steam  is 
made  to  pass  through  the  barrel  in  contact  with  the  heated 
iron  turnings.     Under  these  circumstances,  the  oxygen  of 
the  water  unites  with  the  iron,  and  the  hydrogen  escapes 
in  the  gaseous  state  through  the  flexible  tube. 

831.  The  decomposition  of  water  by  sulphurets,  phos- 
phurets,  and  the  alkaline  metals  will  be  illustrated  in  due 
time. 

Water  produced  by  an  inflamed  Jet  of  Hydrogen. 

832.  The  recomposition  of  water  may  be  rendered  evi- 
dent, by  means  of  the  philosophical  candle,  (305,)  or  any 
other  inflamed  jet  of  hydrogen,  situated  within  a  large 


Apparatus  for  the  Recomposition  of  Water. 


(Page  153.) 


HYDROGEN. 


153 


glass  globe.  The  glass  becomes  immediately  covered  with 
a  dew,  arising  from  the  condensation  of  aqueous  vapour, 
produced  by  the  union  of  the  oxygen  of  the  air  with  the 
hydrogen. 

Lavoisier's  Apparatus  for  the  Recomposition  of  Water. 

833.  This  apparatus  consists  of  a  glass  globe,  with  a  neck  cemented  into  a  brass 
cap,  from  which  three  tubes  proceed,  severally  communicating  with  an  air  pump, 
and  with  reservoirs  of  oxygen  and  hydrogen.  It  has  also  an  insulated  wire  for  pro- 
ducing the  inflammation  of  a  jet  of  hydrogen  by  means  of  an  electric  spark.  In 
order  to  put  the  apparatus  into  operation,  the  globe  must  be  exhausted  of  air,  and 
supplied  with  oxygen  to  a  certain  extent.  In  the  next  place,  hydrogen  is  allowed  to 
enter  in  a  jet,  which  is  to  be  inflamed  by  an  electric  spark.  As  the  oxygen  is  con- 
sumed, more  is  to  be  admitted. 


834.  I  have  employed  a  wire  ignited  by  galvanism  to  inflame  the  hydrogen  in  this 
apparatus,  and  conceive  it  to  be  a  much  less  precarious  method  than  that  of  employ- 
ing an  electrical  machine,  or  electrophorus.    (839). 

Description  of  an  improved  Apparatus  for  the  Recomposition  of  Water. 

835.  This  apparatus  is  represented  by  the  opposite  engraving.     An  inverted  bell 
glass,  with  a  conical  neck,  is  so  closed  at  the  apex  in  the  making,  as  to  form  a  trans- 
parent converging  cavity,  suitable  to  render  the  presence  of  a  very  small  quantity  of 
any  contained  liquid  perceptible  to  the  eye. 

836.  By  means  of  the  screw  rod  and  plate  frame,  (248,)  this  bell  glass  is  secured 
in  an  inverted  position  and  made  air-tight.    With  the  aid  of  three  valve  cocks,  V  V  V, 
and  as  many  leaden  pipes,  communications  with  an  air  pump,  a  barometer  gauge, 
and  a  receiver  sufficiently  supplied  with  oxygen,  may  be  severally  opened  or  closed 
at  pleasure.     Through  a  stuffing  box  which  surmounts  the  plate,  a  copper  pipe,  P 

20 


154  INORGANIC  CHEMISTRY. 

\ 

is  so  passed  as  to  occupy  the  axis  of  the  bell  glass,  and  that  of  a  coil  of  platinum 
wire,  appertaining  to  a  galvano-ignition  apparatus,  (335,  &c.)  The  copper  pipe  ter- 
minates below  in  a  small  platinum  tube,  and  above,  outside  of  the  receiver,  in  a 
cock  C,  and  gallows  screw,  by  which  and  a  leaden  pipe,  a  communication  with  a 
self-regulating  reservoir  of  hydrogen  is  at  command. 

837.  The  apparatus  having  been  thus  arranged,  the  bell  is  to  be  exhausted,  and 
oxygen  admitted,  until  the  gauge  indicates  the  pressure  within  the  receiver  to  be 
nearly  the  same  as  that  of  the  atmospnere.  In  the  next  place,  the  platinum  wire 
being  ignited,  a  jet  of  hydrogen  is  admitted,  which  of  course  inflames,  and  continues 
to  burn  so  long  as  the  supply  of  the  gases  is  kept  up.  Soon  after  the  inflammation 
of  the  hydrogen,  the  resulting  water  will  be  seen  to  coat  the  interior  of  the  bell 
glass  in  drops,  resembling  a  heavy  dew,  and,  continuing  to  accumulate,  will  descend 
in  streams  into  the  converging  neck  of  the  bell  glass.  By  surrounding  this  with 
cold  water,  the  condensation  may  be  expedited,  and  the  deposition  of  water  soon 
rendered  strikingly  evident.  The  gauge  employed  in  this  process  is  that  already 
described.  (137,  &c.) 

838.  Of  the  Air  in  Water.     Water  naturally  contains 
fair.     It  is  to  receive  the  influence  of  the  oxygen  of  the  air 
thus'  existing  in  water,  that  fishes  are  furnished  with  gills, 
which  perform  to  a  certain  extent  the  office  of  lungs  in  de- 
carbonizing blood.     Fishes  cannot  live  in  water  which, 
either  by  boiling  or  exhaustion,  has  been  entirely  deprived 
of  air. 

839.  The  habitudes  of  other  gaseous  substances  with 
water  will  be  more  advantageously  illustrated,  when  those 
substances  are  under  consideration. 


Experimental  Proof  of  the  Presence  of  Air  in  Water. 

840.  Water  exposed  to  the  action  of  an  air  pump,  or 
otherwise  subjected  to  exhaustion,  becomes  replete  with 
air  bubbles. 

841.  Of  the  Moisture  in  Air. — Air  is  not  more  invariably 
attendant  upon  water  than  water  is  upon  air;  nor  is  the  air 
in  water  more  necessary  to  fishes,  than  the  water  in  the 
air  to  animals  and  vegetables.  (229,  &c.) 

842.  The  well  known  deleterious  influence  of  the  winds 
which  blow  from  the  African  deserts,  arises  probably  from 
their  aridity.     The  desiccating  power  of  air  is  directly  as 
its  temperature,  and  inversely  as  the  quantity  of  moisture 
previously  associated  with  it. 

843.  There  is  a  certain  proportion  of  moisture,  rela- 
tively to  the  temperature,  which  is  most  favourable  to  our 
comfort.     If  the  moisture  be  increased  without  raising  the 
temperature,  or  the  temperature  be  increased  without  an 
accession  of  moisture,  we  are  incommoded.     In  the  one 
case,  the  skin  becomes  unpleasantly  dry;  in  the  other,  the 
air  is  too  much  encumbered  with  aqueous  vapour,  to  allow 


HYDROGEN.  155 

perspiration,  whether  sensible  or  insensible,  to  proceed  with 
sufficient  freedom. 

844.  Stove  rooms  are  oppressive  on  account  of  the  too 
great  aridity  of  the  air  in  them;  and  hence  the  well  known 
remedy  of  a  basin  of  water,  placed  upon  the  stove  to  fur- 
nish moisture  by  its  evaporation. 

845.  Hygrometric  Process  of  Dalton. — The  dew  which  is  observable 
on  vessels  containing  cold  water,  in  warm  weather  especially,  arises  from 
the  condensation  of  the  aqueous  vapour  in  the  air. 

846.  According  to  Mr.  Dalton,  the  less  the  degree  of  cold  requisite  to 
produce  this  phenomenon,  the  greater  the  quantity  of  moisture  in  the  air. 
Hence,  by  ascertaining  the  highest  temperature  at  which  the  water  is  capa- 
ble of  producing  the  condensation,  the  quantity  of  moisture  may  be  known 
from  a  table  which  he  has  constructed.     (229,  &c.) 

84?.  DanielVs  Hygrometer. — Mr.  Daniell  has  contrived  an  hygrometer 
upon  the  principle  thus  suggested  by  Dalton.  Vaporization  is  ingeniously 
applied  to  produce  cold  in  one  bulb  of  the  instrument,  in  consequence  of  the 
cold  produced  by  the  evaporation  of  ether  in  another  bulb,  as  in  the  cryo- 
phorus.  (407,  &c.)  Two  thermometers  accompany  the  instrument,  one 
within  the  bulb  refrigerated  by  the  vaporization;  the  other  so  situated  as  to 
indicate  the  temperature  of  the  atmosphere.  As  the  quantity  of  aqueous 
vapour  in  the  air  diminishes,  the  depression  of  temperature  necessary  to  the 
precipitation  of  moisture  on  the  refrigerated  bulb  increases.  The  extent  of 
the  depression  is  ascertained  by  the  thermometers,  the  quantity  of  water  in 
the  air  by  reference  to  a  table. 

848.  Organic  Sensibility  of  the  Beard  of  the  Wild  Oat  (Avena  Sen- 
sitiva)  to  Moisture. — Hygrometers  have  been  made  which  are  dependent 
upon  the  contraction  or  dilatation  which  catgut,  whalebone,  and  other  sub- 
stances of  a  like  nature  undergo,  in  proportion  to  the  quantity  of  moisture 
in  the  air.     Among  instruments  of  this  kind,  that  formed  by  means  of  the 
beard  of  the  wild  oat  is  pre-eminent  for  its  susceptibility  to  the  influence  of 
moisture.     Breathing  on  it  through  a  minute  hole  in  the  case,  causes  the 
index  to  be  moved  instantaneously.   (222,  &c.)     The  indications  of  hygro- 
meters thus  constructed  are  not  referrible  to  any  standard,  agreeably  to 
which  a  comparison  can  be  made  between  the  dryness  of  the  air  in  dif- 
ferent places  at  the  same  time,  or  in  the  same  place  at  different  times. 

849.  Hygrometric  Process  by  means  of  a  Balance. — It  may  be  pre- 
sumed that  the  quantity  of  moisture  in  the  air  is  inversely  as  the  weight  of 

water  which  will  in  a  given  time  evaporate  from  a  moist  sur- 
face. If  this  presumption  be  correct,  the  little  square  dish 
here  represented  may,  with  the  aid  of  a  delicate  scale  beam, 
be  used  as  an  hygrometer.  If  it  be  suspended  to  the  ba- 
lance, and  equipoised  while  containing  a  little  water,  the 
counter-weight  will  in  a  few  minutes  preponderate,  in  conse- 
quence of  the  loss  by  evaporation. 

850.  The  loss  of  weight  within  any  known  period  being  determined,  the 
evaporating  power  of  the  air  will  be  as  the  loss  of  weight;  but  as  the  eva- 
poration is  more  or  less  rapid  in  proportion  as  there  may  be  more  or  less 
agitation,  it  will  not  be  right  to  infer  that  the  quantity  of  aqueous  vapour  in 
the  atmosphere  is  inversely  as  the  rate  of  evaporation,  unless  the  process 


156  INORGANIC  CHEMISTRY. 

were  uninfluenced  by  the  wind.    Of  course  the  dish  should  be  of  convenient 
dimensions,  accurately  determined ;  2  inches  square  for  instance. 

Compounds  of  Chlorine  with  Water. 

851.  Hydrate  of  Chlorine. — Berzelius  observes  that  chlorine  furnishes 
the  only  instance  of  an  elementary  substance  capable  of  entering  into  com- 
bination with  water.     I  allude  here  to  a  crystalline  compound  formed  on 
passing  the  gas  through  that  liquid  at  a  temperature  below  40°  F.     The 
hydrate  thus  formed  is  capable  of  being  sublimed  from  one  part  of  the  con- 
taining vessel  to  another,  in  consequence  of  a  slight  diversity  of  tempera- 
ture.    It  consists  of  one  volume  of  chlorine,  and  twenty  volumes  of  aqueous 
vapour. 

852.  Solution  of  Chlorine  in  Water. — The  same  eminent  author  al- 
leges that,  in  order  to  obtain  a  saturated  solution  of  chlorine  in  water,  it  is 
necessary,  in  the  first  instance,  to  expel  from  the  latter  all  the  atmospheric 
air. 

Of  the  Deutoxide  or  Bioxide  of  Hydrogen,  or  Oxygenated 

Water. 

853.  In  1818,  Thenard  discovered  that  water  might  be 
made  to  receive  an  additional  quantity  of  oxygen,  by  dis- 
solving deutoxide  of  barium  in  liquid  muriatic  acid,  preci- 
pitating the  baryta  by  sulphuric  acid,  and  the  chlorine  by 
silver. 

854.  Properties. — The  bioxide  of  hydrogen  is  as  liquid, 
and  as  devoid  of  colour  as  water.     It  is  nearly  inodorous, 
whitens  the  tongue,  inspissates  the  saliva,  and  tastes  like 
some  metallic  solutions.     Applied  to  the  skin,  it  creates  a 
smarting  sensation,  more  durable  in  some  persons  than  in 
others.    Its  specific  gravity  is  1.452.  Hence,  when  poured 
into  water,  it  descends  through  it  like  syrup,  but  is  dis- 
solved by  agitation.     As  it  is  less  easy  to  vaporize  than 
water,  it  may  be  separated  from  that  liquid,  by  exposure  in 
vacuo  over  sulphuric  acid.  (309.)     In  its  most  concen- 
trated form,  it  has  not  been  congealed  by  any  degree  of 
cold  to  which  it  has  been  subjected.     The  most  surprising 
property  of  this  substance  is  that  of  giving  off  oxygen 
explosively,  on  being  brought  into  contact  with*  substances 
which  do  not  unite  with  either  of  its  ingredients.     Thus  it 
explodes  by  contact  with  finely  divided  silver,  platinum  or 
gold,  and  still  more  actively  with  oxide  of  silver  or  perox- 
ide of  lead.     The  difficulty  of  explaining  these  phenomena 
has  already  been  noticed.  (421,  &e.) 

855.  When  mingled  with  the  mineral  acids,  its  liability 
to  decomposition  is  diminished.     If  exposed  to  heat  in  its 


HYDROGEN.  157 

most  concentrated  state,  a  few  grains  create  a  violent  ex- 
plosion. When,  by  dilution  with  20  parts  of  water  and 
exposure  to  heat,  it  loses  all  the  oxygen  which  it  holds  be- 
yond the  quantity  necessary  to  the  composition  of  water, 
as  much  oxygen  is  found  to  be  evolved  as  the  hydrogen  in 
the  residual  water  retains.  Hence  it  is  generally  supposed 
to  consist  of  one  atom  of  hydrogen  and  two  of  oxygen. 

Remarks  on  Nomenclature. 

856.  Some  of  the  most  eminent  European  chemists  have,  most  errone- 
ously and  inconsistently,  designated  the  acids  formed  by  hydrogen,  with  the 
electronegative,  or  basacigen  bodies,  as  hydracids ;  while  analogous  com- 
pounds, formed  by  other  radicals,  were  designated  by  prefixing  syllables 
indicative  of  the  electro-negative  ingredient.     Thus  we  have  had  hydro- 
chloric, hydrobromic,  hydroiodic,  hydrofluoric,  hydrocyanic,  &c.,  to  sig- 
nify the  acid  compounds  of  hydrogen  with  the  halogen  elements ;  while 
we  have  had  fluoboric  and  fluosilicic  to  signify  acids  formed  with  the  ra- 
dicals boron  and  silicon  by  fluorine.     Thus  the  former  series  is  character- 
ized by  letters  taken  from  the  radical,  the  latter  by  letters  taken  from  the 
electro-negative  or  basacigen  ingredient,  while  hydrogen  is  placed  by  the 
side  of  oxygen,  with  which,  in  properties,  it  is  extremely  discordant.    (633, 
636.) 

857.  This  error  I  pointed  out  in  an  article  published  in  the  Journal  of 
Pharmacy,  in  the  autumn  of  1833,  and  in  a  letter  to  Professor  Silliman.* 

*  The  following  passage  is  in  the  letter  to  which  I  have  referred. 

"  In  common  with  other  eminent  chemists,  Berzelius  has  distinguished  acids  in 
which  oxygen  is  the  electro-negative  principle,  as  oxacids,  and  those  in  which  hy- 
drogen is  a  prominent  ingredient,  as  hydracids.  If  we  look  for  the  word  radical  in 
the  table  of  contents  of  his  invaluable  Treatise,  we  are  referred  to  p.  218,  vol.  1st, 
where  we  find  the  following  definition,  "  the  combustible  body  contained  in  an  acid, 
or  in  a  salijiable  base,  is  called  the  radical  of  the  acid,  or  of  the  base."  In  the  second 
vol.  page  163,  he  defines  hydracids  to  be  "  those  acids  which  contain  an  electro- 
negative body  combined  with  hydrogen;"  and  in  the  next  page  it  is  stated,  that  "hy- 
dracids are  divided  into  those  which  have  a  simple  radical,  and  those  which  have  a 
compound  radical.  The  second  only  comprises  those  formed  with  cyanogen  and  sul- 
phocyanogen."  Again,  in  the  next  paragraph,  "  no  radical  is  known  that  gives  more 
than  one  acid  with  hydrogen,  although  sulphur  and  iodine  are  capable  of  combining 
with  it  in  many  proportions.  If  at  any  future  day  more  numerous  degrees  of  acidi- 
fication with  hydrogen  should  be  discovered,  their  denomination  might  be  founded 
on  the  same  principles  as  those  of  oxacids."  Consistently  with  these  quotations,  all 
the  electro-negative  elements  forming  acids  with  hydrogen  are  radicals,  and  of 
course,  by  his  own  definition,  combustibles;  while  hydrogen  is  made  to  rank  with 
oxygen  as  an  acidifying  principle,  and  consequently  is  neither  a  radical  nor  a  com- 
bustible. Yet,  page  189,  vol.  2d,  in  explaining  the  reaction  of  fluoboric  acid  with 
water,  in  which  case  fluorine  unites  both  with  hydrogen  and  boron,  it  is  mentioned 
as  one  instance  among  others  in  which  fluorine  combines  with  two  combustibles. 

"  I  am  of  opinion  that  the  employment  of  the  word  hydracid,  as  co-ordinate  with 
oxacid,  must  tend  to  convey  that  erroneous  idea,  with  which,  in  opposition  to  his 
own  definition,  the  author  seems  to  have  been  imbued,  that  hydrogen  in  the  one 
class,  plays  the  same  part  as  oxygen  in  the  other.  But  in  reality,  the  former  is  emi- 
nently a  combustible,  and  of  course  the  radical  by  his  own  definition. 

"  Dr.  Thomson,  in  his  system,  does  not  recognise  any  class  of  acids  under  the  ap- 
pellation of  hydracids,  but,  with  greater  propriety  as  I  conceive,  places  them  under 
names  indicating  their  electro-negative  principles.  Thus  he  arranges  them  as  oxy- 
gen acids,  chlorine  acids,  bromine  acids,  iodine  acids,  fluorine  acids,  cyanogen  acids, 
sulphur  acids,  selenium  acids,  and  tellurium  acids.  These  appellations  might,  I 


158  INORGANIC  CHEMISTRY. 

Afterwards  I  had  the  satisfaction  of  observing,  that,  in  an  edition  of  his 
Traite,  then  in  the  press,  Thenard  was  acting  upon  a  similar  view  of  this 
subject,  and  employing  the  language  which  I  had  suggested.  Moreover  I 
found  that  Dr.  Thomson  had  not  arranged  the  acids  alluded  to  under  the 
name  of  hydracids,  but  had  put  each  of  them  under  the  name  of  its  electro- 
negative ingredient.  Hence  they  were  treated  of  under  as  many  heads  as 
there  are  basacigen  bodies.  Or,  to  be  more  particular;  they  were  treated 
of  as  oxygen  acids,  chlorine  acids,  bromine  acids,  iodine  acids,  fluorine 
acids,  cyanogen  acids,  sulphur  acids,  selenium  acids,  and  tellurium  acids. 

858.  Consistently  with  the  process  of  abbreviation  by  which  oxacid  has 
been  employed  to  designate  an  acid  formed  by  oxygen,  and  hydracid  to 
signify  an  analogous  combination  formed  with  hydrogen,  I  have  made  the 
following  abbreviations  of  the  appellations  employed  by  Thomson : — 

For  Oxygen  acids  to  use  Oxacids. 

„  Chlorine  acids  „  Chloracids. 

„  Bromine  acids  „  Bromacids. 

„  Iodine  acids  „  lodacids. 

„  Fluorine  acids  ,,  Fluacids. 

„  Cyanogen  acids  „  Cyanacids. 

„  Sulphur  acids  „  Sulphacids. 

„  Selenium  acids,  „  Selenacids. 

,,  Tellurium  acids  „  Telluracids. 

859.  The  acids  formed  by  oxygen  received  their  names,  for  the  most 
part,  before  the  basacigen  bodies  were  recognised  as  elements,  or  the  exist- 
ence of  some  of  them  discovered.     Hence,  in  the  case  of  the  oxacids,  it  is 
neither  customary  nor  expedient,  to  prefix  any  syllables  indicating  their 
basacigen  ingredient.     Consequently,  we  have  sulphuric,  selenic,  telluric, 
chloric,  bromic,  iodic,  &c.  &c.  instead   of  oxysulphuric,  oxyselenic,  oxy- 
telluric,  oxychloric,  oxybromic,  oxiodic,  &c.'    The  syllables  were  employed 
prior  to  the  recognition  of  the  elementary  character  of  chlorine,  to  desig- 
nate an  oxacid  with  an  extra  proportion  of  oxygen.     Thus  chlorine  was 

think,  be  advantageously  abbreviated  into  oxacids,  chloracids,  bromacids,  iodacids, 
fluacids,  cyanacids,  sulphacids,  selenacids,  telluracids. 

"  I  had  formed  my  opinions  on  this  subject  before  I  was  aware  that  Dr.  Thomson 
had  resorted  to  this  classification. 

"  As  respects  the  acids  individually,  I  conceive  that  it  would  be  preferable,  if  the 
syllable  indicating  the  more  electro-negative  element  had  precedency  in  all,  as  it 
has  in  some  cases.  The  word  hydrofluoric  does  not  harmonize  with  fluoboric,  fluo- 
silicic,  fluochromic,  fluomolybdic,  &c.  Fluorine  being  in  each  compound  the  electro- 
negative principle,  the  syllables,  indicating  its  presence,  should  in  each  name  occupy 
the  same  station.  These  remarks  will  apply  in  the  case  of  acids  formed  with  hydro- 
gen by  all  principles  which  are  more  electro-negative.  Hence  we  should  use  the 
terms  chlorohydric,  bromohydric,  iodohydric,  fluohydric,  cyanhydric,  instead  of  hy. 
drochloric,  hydrobromic,  hydriodic,  hydrofluoric,  hydrocyanic. 

"  As  by  the  British  chemists  the  objectionable  words  have  not  been  definitively 
adopted,  the  appellations  muriatic  and  prussic  being  still  much  employed,  it  may  not 
be  inconvenient  to  them  to  introduce  those  which  are  recommended  by  consistency. 
In  accordance  with  the  premises,  the  acids  formed  with  hydrogen  by  sulphur,  seleni- 
um, and  tellurium,  would  be  called  severally  sulpbydric.  selenhydric,  and  telluhydric 
acid.  Compounds  formed  by  the  union  of  the  acids,  thus  designated,  with  the  bases  se- 
verally generated  by  the  same  electro-negative  principles,  would  be  called  sulphy- 
drates,  selenhydrates,  and  telluhydratcs,  which  are  the  names  given  to  these  com- 
pounds in  the  Berzelian  nomenclature.  Influenced  by  the  analogy,  a  student  would 
expect  the  electro-negative  ingredient  of  a  sulphydrate  to  be  sulphydric  acid,  not  a 
sulphide.  The  terminating  syllable  of  this  word,  by  its  associations,  can  only 
convey  the  conception  of  an  electro-positive  compound." 


HYDROGEN.  159 

miscalled  oxymuriatic  acid,  being  supposed  to  be  an  oxide  of  an  unknown 
radical,  with  an  extra  dose  of  oxygen.  (888.)  At  this  time,  oxychloric 
acid  designates  the  acid  which  has  more  oxygen  than  the  chloric  acid. 

860.  The  analogy  between  the  acids  formed  by  hydrogen  with  the  halo- 
gen bodies,  chlorine,  bromine,  iodine,  fluorine,  and  cyanogen,  render  it  both 
desirable  and  practicable  to  treat  of  them  in  a  body,  mainly  by  reference  to 
chlorohydric  acid.     Hence  I  shall  employ  the  word  halokydric,  to  desig- 
nate those  acid  compounds;  and  in  obedience  to  similar  considerations,  the 
compounds  formed  with  hydrogen  by  the  amphigen  bodies,  sulphur,  sele- 
nium, and  tellurium,  will  be  designated  as  amphydric  acids. 

861.  The  compound  formed  by  the  union  of  hydrogen  with  oxygen,  the 
protoxide  of  hydrogen,  (water,)  ought  not  to  be  included  under  the  head  of 
the  amphydric  acids.     Of  this  oxide,  the  pretensions  to  the  characteristics 
of  a  base,  are  at  least  as  high  as  those  which  can  be  advanced  for  it  as  an 
acid.     Of  course  it  cannot,  with  propriety,  be  classed  with  any  acid  com- 
pounds.    It  is  in  reality  an  anomalous  substance,  performing  a  part  in  na- 
ture of  such  pre-eminent  importance,  as  to  merit  to  a  certain  extent  an  iso- 
lated position,  and  undivided  attention. 

862.  Names  of  the  halohydric  acids,  or  those  formed  by  the 
Jive  halogen  bodies,  chlorine,  bromine,  iodine,  fluorine  and 

cyanogen,  with  hydrogen,  as  heretofore  given  by  the  French 
chemists,  also  by  Berzelius,  Turner,  and  others,  contrasted 
with  those  now  employed  in  this  Compendium,  agreeably  to 
the  practice  of  Thenard,  and  with  the  approbation  of  Ber- 
zelius.* 

For  hydrochloric  use  chlorohydric. 

„    hydrobromic  „  bromohydric. 

„    hydroiodic  „  iodohydric. 

„    hydrofluoric  „  fluohydric. 

„    hydrocyanic  „  cyanohydric. 

863.  Names  of  the  amphydric  acids,  or  acids  formed  by  the 
amphygen  bodies  of  Berzelius  (excepting  oxygen}  with  hy- 
drogen. 

For  hydrosulphuric      use      sulphydric. 
„    hydroselenic  „        selenhydric. 

„    hydrotelluric  „        telluhydric. 

*  I  cheerfully  admit  that  it  would  be  preferable  to  employ  the  word  chlorohydric, 
instead  of  hydrochloric.  My  motive  for  retaining  this  last,  was,  that  I  was  unwill- 
ing to  venture  upon  a  new  nomenclature  in  a  language  foreign  to  me,  in  which  it 
was  inexpedient  to  make  changes  which  could  be  avoided  without  inconvenience. 
I  also  agree  with  you,  that  we  ought  not  to  use  combustible  and  oxidable,  as  having 
the  same  meaning.  I  have  deserved  your  strictures  for  this  inconsistency  in  my 
language;  but  I  must  suggest  as  an  apology,  that  the  two  words  were  formerly  used 
as  synonymous,  and  that  the  work,  in  which  you  have  recently  noticed  this  over- 
sight, was  first  published  in  1806,  having  been  from  time  to  time  remoulded  for  new 
editions,  without  its  having  been  possible  to  eradicate  all  that  has  not  kept  pace  with 
the  progress  of  science. 


160  INORGANIC  CHEMISTRY. 

COMPOUND  OF  HYDROGEN  WITH  CHLORINE. 
Of  Chlorohydric  or  Muriatic  Acid  Gas. 

864.  When  hydrogen  and  chlorine  are  mixed  in  equal 
volumes  they  combine  spontaneously.      In  the  dark,  or 
where  the  light  is  feeble,  the  union  is  slowly  accomplished, 
but,  in  the  solar  rays,  takes  place  explosively.     According 
to  Silliman,  the  direct  rays  of  the  sun  are  not  necessary  to 
produce  the  result.     The  mixture  may  also  be  exploded  by 
the  electric  spark,  or  by  contact  with  any  ignited  matter. 
However  the  union  may  be  effected,  chlorohydric  or  mu- 
riatic acid  gas  is  produced,  without  any  reduction  of  vo- 
lume if  no  water  be  present. 

Synthesis  of  Chlorohydric  Acid  Gas. 

865.  In  order  to  demonstrate  the  "ratio  in  which  chlo- 
rine and  hydrogen  combine,  it  is  only  necessary  to  intro- 
duce and  ignite  in  the  volumescope  over  water,  equal  mea- 
sures of  each  gas.    If  they  be  pure,  there  will  be  a  complete 
condensation.     The  experiment  is  conducted  precisely  as 
in  the  case  of  oxygen  and  hydrogen,  excepting  that  in  lieu 
of  a  half  volume  of  oxygen,  a  volume  of  chlorine  is  sup- 
plied from  a  self-regulating  reservoir.    (798.) 

Explosive  Reaction  of  Hydrogen  with  Chlorine,  under  the  influence  of 

the  Solar  Rays. 

866.  A  flask  is  half  filled  with 
|W                          chlorine  over  the  pneumatic  cis- 
tern in  the  usual  way,  and  then 
transferred  to  the  pan  P,  so  as  to 
have  its  orifice  exactly  over  that 
of  a  pipe  which,  at  the  other  end, 
communicates  with  the  cock  C, 
to   which  is  annexed  a  flexible 
pipe  extending  to  a  self- regulat- 
ing reservoir  of  hydrogen.  (799.) 

867.  "The  flask  is  surrounded 
by  a  wire  gauze,  W,  and  just  be- 
fore the  explosion  is  desired,  hy- 
drogen from  the  reservoir  is  al- 
lowed to  occupy  that  portion  of 
the  cavity  which  was  previously 
unoccupied  by  the  chlorine.     It 

should  be  understood  that  the  pan,  during  this  operation,  retains  a  sufficient 
stratum  of  water  to  cover  the  mouth  of  the  flask,  and  that  this  is  occupied 
with  the  same  liquid  in  part  until  it  is  displaced  by  the  hydrogen. 

868.  The  preliminary  arrangements  being  made,  a  mirror  must  be  placed 


HVDROGEN. 


161 


in  a  situation  to  receive  the  solar  rays  without  passing  through  window  glass, 
and  to  reflect  them  upon  the  flask.  The  result  is  an  explosion,  from  the 
effects  of  which  the  spectators  are  protected  by  the  wire-gauze. 

869.  It  must  be  obvious  that  this  experiment  can  only  succeed  when  the 
sun  is  unobscured. 

870.  It  should  be  understood  that  the  condensation  arises  altogether  from 
the  absorption  of  the  gas  by  the  water.    (866.) 

Preparation  of  Chlorohydric  or  Muriatic  Acid  Gas. 


871.  Into  a  tubulated  retort,  introduce  about  as  much 
chloride  of  sodium  (common  salt)  as  will  occupy  nearly 
one-third  of  the  body,  A.  Lute  a  glass  funnel,  furnished 
with  a  cock,  into  the  tubulure.  Let  the  orifice  of  the  beak, 
B,  be  so  depressed  below  the  surface  of  the  mercury  in  the 
cistern,  as  to  be  under  a  bell  glass,  filled  with,  and  inverted 
over,  the  mercury,  and  properly  situated  for  receiving  any 
gas  which  may  escape  through  the  beak.  Prepare  about 
three-fourths  as  much  strong  sulphuric  acid  by  weight  as 
there  may  be  salt  in  the  retort.  After  pouring  about  one- 
third  of  the  acid  into  the  retort,  close  the  cock  of  the  fun- 
nel: the  mixture  will  rise  in  a  foam,  and  a  portion  of  gas- 
eous matter  will,  pass  into  the  bell.  As  soon  as  the  foam 
subsides,  add  more  of  the  acid  until  the  whole  is  intro- 
duced. Then  as  soon  as  the  foam  again  subsides,  apply 
the  chauffer,  C,  and  chlorohydric  acid  gas  will  continue  to 
be  copiously  evolved.  I  have  of  late  substituted  for  the 
funnel  a  glass  tube  of  about  a  half  an  inch  in  bore  at  one 
end,  tapering,  at  the  other  end,  to  an  orifice  of  about  the 
eighth  of  an  inch  in  bore.  This  tube,  being  inserted  into 
the  retort  through  the  tubulure,  and  luted  thereto  air-tight, 
21 


162  INORGANIC    CHEMISTRY. 

affords  a  channel  for  the  gradual  introduction  of  the  acid, 
which,  surrounding  the  lower  orifice  of  the  tube,  prevents 
the  gas  from  escaping. 

872.  Rationale  of  the  Process. — The  water  combined 
with  the  sulphuric  acid  is  decomposed;  its  oxygen  unites 
with  the  sodium,  forming  soda,  with  which  the  sulphuric 
acid  combines,  forming  sulphate  of  soda.     The  hydrogen 
of  the  water  and  the  chlorine  escape  as  chlorohydric  acid 
gas. 

873.  Properties. — Chlorohydric  acid  has  all  the  attri- 
butes of  a  gas.     It  is  colourless,  and,  although  less  active 
than  chlorine  gas,  is  to  the  organs  of  respiration  intolera- 
bly irritating,  and  if  not  very  dilute,  deleterious  to  life. 
On  escaping  into  the  air,  it  produces  white  fumes,  from  its 
meeting  with  moisture.     Its  affinity  for  water  is  so  great, 
that  this  liquid  will  take  up  420  times  its  bulk,  and  when 
in  this  state,   ice  is  liquefied  as  if  surrounded  by  fire. 
When  brought  into  contact  with  the  metals  which  decom- 
pose water,  its  hydrogen  is  liberated,  while  the  chlorine 
unites  with  the  metal.     Equal  weights  of  potassium  sepa- 
rate the  same  weights  and  volumes  of  hydrogen  from  chlo- 
rohydric acid,  and  from  water;  a  result  conformable  with 
the  inferred  atomic  composition  of  both.    Presented  to  me- 
tallic oxides,  a  reciprocal  decomposition  ensues ;  the  hydro-, 
gen  unites  with  the  oxyen  generating  water,  the  chlorine 
with  the  metal  producing  a  chloride.     If  mingled  with  oxy- 
gen and  exposed  to  the  action  of  heat  or  a  succession  of 
electric  sparks,  gaseous  chlorohydric  acid  is  partially  de- 
composed.    This  result  cannot  be  extended  to  more  than 
sVth  of  the  whole  volume.     At  the  temperature  of  50°,  and 
under  a  pressure  of  forty  atmospheres,  it  becomes  a  colour- 
less liquid. 

874.  Its  specific  gravity  is  1.2694,  a  mean  between  that 
of  its  constituents.     The  weight  of  100  cubic  inches  is 
39.36  grains. 

One  atom  of  chlorine,  equivalent  36 

And  one  atom  of  hydrogen,  equivalent  1 

Constitute  one  atom  of  chlorohydric  acid  gas, 

equivalent  37 


HYDROGEN.  163 

Experimental  Illustrations. 

875.  Equal  volumes  of  hydrogen  and  chlorine,  being 
mixed  and  subjected  to  the  solar  rays,  (867,)  or  galvanic 
ignition,  (818,)  explode  and  form  chlorohydric  acid  gas. 

876.  Gas  collected  over  mercury  in  tall  jars.     Water, 
coloured  by  litmus,  being  introduced,  rapidly  changes  to  a 
red  colour,  and  causes  the  disappearance  of  the  gas.    Same 
effect  produced  by  ice,  which  is  rapidly  melted. 

Preparation  of  Liquid  Chlorohydric  or  Muriatic  Acid. 

877.  It  may  be  obtained  by  saturating  water  with  the 
gas  in  Woulfe's  apparatus.  (See  the  following  figure.)  The 
solution  is  nearly  pure  in  all  the  receptacles  excepting  the 
first. 

Woulfe's  Apparatus. 


878.  By  this  figure  Woulfe's  apparatus  is  depicted  in  an  improved  form.     The 
gas  evolved  in  the  retort,  first  passes  into  the  globe  where  any  vapour  which  may 
accompany  it  condenses.     It  then  proceeds  along  the  tube  which  establishes  a  com- 
munication  with  the  bottle  next  to  the  globe.     As  that  mouth  of  this  tube  which  is 
within  the  bottle,  is  below  the  surface  of  the  liquid  placed  there  to  absorb  it,  the  gas 
has  to  bubble  up  through  the  liquid,  so  as  to  promote  its  own  absorption  by  the  agi- 
tation thus  induced.    It  then  rises  above  the  surface  of  the  liquid,  where  a  further 
absorption  takes  place.     The  excess  of  gas,  beyond  the  quantity  absorbed  by  the  li- 
quid in  the  first  bottle,  passes,  by  means  of  the  connecting  tube,  to  the  second  bottle, 
and  whatever  portion  is  not  there  absorbed,  reaches  the  third  bottle,  in  the  case  of 
which  the  process  proceeds  as  in  that  of  the  first  two.     Should  any  of  the  gas  escape 
the  whole  series,  it  may,  by  lengthening  the  last  tube,  be  conducted  under  a  bell 
glass  filled  with  water  on  the  shelf  of  the  hydro-pneumatic  cistern,  so  as  not  to  an- 
noy the  operator.     But  this  never  takes  place  in  the  case  of  chlorohydric  acid  gas, 
until  the  water  is  nearly  saturated. 

879.  Supposing  the  extrication  of  gas  to  cease  before  the  liquid  in  the  first  bottle 
is  saturated,  the  absorption  continuing,  the  liquid  in  the  second  bottle  might  be  trans- 
ferred  to  the  first,  in  consequence  of  the  rarefaction  of  the  residual  gas  rendering  it 
incompetent  to  resist  the  atmospheric  pressure.     In  like  manner  the  contents  of  the 
third  bottle  might  be  transferred  to  the  second.     To  prevent  these  inconveniences, 
there  is  in  each  bottle  a  straight  tube  fastened  air-tight  into  an  intermediate  neck, 
and  descending  into  the  liquid.     By  these  means  an  adequate  pressure  is  opposed 
to  the  escape  of  the  gas,  and  yet  any  diminution  of  pressure,  arising  from  absorption, 
will  be  compensated  by  the  ingress  of  atmospheric  air,  ere  the  liquid  can  be  drawn 
over  from  the  next  bottle.     To  prevent  absorption  from  the  first  bottle  into  the  globe, 
it  is  best  to  use,  for  the  introduction  of  the  acid,  a  trumpet-mouthed  tube  of  small 
bore,  passing  through  and  luted  into  the  tubulure  by  a  cork  with  lead  and  a  gum 
elastic  bandage,  and  terminating  in  a  small  orifice  near  the  bottom  of  the  retort  inside. 


164 


INORGANIC  CHEMISTRY. 


880.  Of  late  I  have  resorted  to  the  following  expedient.    The  beaks  of  four  tubu- 
lated retorts,  are  drawn  out  by  heating  them  in  a  hole  opened  by  a  poker  in  an  an- 
thracite fire,  until  the  beak,  by  its  own  weight,  is  made  to  extend  itself  into  a  long 
tapering  tube.     At  the  moment  when  this  takes  place,  by  lifting  it  from  the  fire  and 
holding  the  body  of  the  retort  in  a  suitable  position,  the  tapering  portion  of  the  beak 
hangs  down,  making  the  desired  angle  with  the  other  part  of  the  beak.     Of  course  it 
retains  this  form  when  cold.    The  retorts  thus  prepared,  are  so  associated  th,at  the  beak 
of  No.  1,  the  larger  retort,  may  enter  No.  2,  through  the  tubulure  of  No.  2,  and  that 
the  beak  of  this  may  in  like  manner  reach  into  No.  3.     Of  course  a  fourth  and  a  fifth 
retort  may,  if  requisite,  be  thus  made  to  communicate.     The  beaks  are  to  be  luted  to 
the  tubulures;  and  No.  1,  being  supplied  with  the  salt,  and  furnished  with  a  tapering 
tube  for  the  introduction  of  the  sulphuric  acid,  the  process  is  to  be  conducted  as  al- 
ready described.  (873,  &c.) 

881.  Commercial  chlorohydric  acid  is  so  cheap,  that  I  have  found  it  preferable  to 
use  it  in  the  first  retort,  instead  of  salt.     The  addition  of  sulphuric  acid  causes  the 
gas  to  come  over  pure,  without  heat  at  first,  but  with  the  aid  of  a  gentle  heat,  nearly 
the  whole  may  be  evolved,  and  of  course  absorbed  by  the  water,  placed  purposely 
within  retorts,  No.  2  and  3.     It  is  preferable  to  add  a  fourth  retort,  and  to  have 
No.  2  quite  small,  holding  only  a  small  quantity  of  water,  just  adequate  to  wash  out 
of  the  gas  any  sulphuric  acid  which  may  attend  it  in  the  form  of  a  spray.     It  may 
be  remarked,  that  one  advantage  of  this  process  is,  that  the  iron  which  is  usually  an 
impurity  in  liquid  chlorohydric  acid,  forms  a  compound  with  sulphuric  acid,  which 
is  not  like  the  chloride  of  that  metal,  volatile.     Consequently,  by  this  process,  the 
acid  is  depurated  of  iron. 

882.  Liquid  chlorohydric  acid  may  also  be  obtained  by  distilling  a  solution  of 
chloride  of  sodium  in  water  with  sulphuric  acid.     In  this  way  there  is  no  need  of  an 
apparatus  for  promoting  absorption,  as  described  in  the  preceding  article.     The  acid 
comes  over  and  condenses  in  union  with  the  requisite  quantity  of  water. 

883.  Properties  of  the  Liquid  Chlorohydric  Acid. — When 
concentrated,  it  produces  suffocating  fumes  from  the  es- 
cape of  gas.    When  pure,  it  is  colourless,  though  usually 
straw-coloured  from  the  presence  of  a  minute  portion  of 
iron. 

884.  Dr.  Thomson  informs  us  that  the  strongest  liquid 
acid  which  he  could  obtain,  consisted  of  one  atom  of  acid, 
equivalent  37,  united  with  six  atoms  of  water,  which  being 
equivalent   to  54,  the   proportion  of  acid   to  water   by 
weight  was  as  those  numbers,  or  nearly  as  2  to  3.* 

*  The  relative  equivalent  proportion  of  chlorohydric  acid  and  water,  or  proportion 
of  said  acid,  by  weight,  in  aqueous  solutions  of  different  specific  gravities,  may  be 
learned  from  the  following  table.  (See  Thomson's  Principles  of  Chemistry.) 


Atoms  of 
Acid. 

Atoms  of 

Water. 

Real  Acid  in  100 
of  the  Liquid. 

Specific 
Gravity. 

I 

6 

40.659 

1.203 

7 

37.000 

1.179 

8 

33.945 

1.162 

o 

31  .346 

.149 

10 

29.134 

.139 

11 

27.200 

.1285 

12 

25.517 

.1197 

13 

24.026 

.1127 

14 

22.700 

.1060 

15 

21.512 

.1008 

16 

20.442 

.0960 

17 

19.474 

.0902  - 

18 

18.590 

.0860 

19 

17.790 

.0820 

20 

17.051 

.0780 

HYDROGEN.  165 

Experimental  Illustrations. 

885.  Liquid  chlorohydric  acid  exhibited;  also  its  reac- 
tion with  other  bodies. 

Of  the  Old  Theory  of  the  Nature  of  Chlorine  and  Chlorohydric  Acid. 

886.  Chlorohydric  acid  was  deemed  to  be  a  compound  of  oxygen  with 
some  unknown  radical.     When  distilled  from  red  oxide  of  lead,  or  black 
oxide  of  manganese,  it  was  supposed  to  combine  with  a  portion  of  the  oxy- 
gen of  those  oxides,  forming  oxygenated  muriatic  acid,  the  name  then 
given  to  chlorine.     To  the  oxygen  thus  imagined  to  exist  in  it,  the  activity 
of  chlorine,  as  a  supporter  of  combustion  and  as  a  solvent  of  metals,  was 
ascribed.     It  has  since  been  proved  that  neither  carbon  nor  the  metals  are 
oxidized  when  intensely  ignited  in  dry  chlorine.  '  The  metals  are  converted 
into  chlorides,  while  the  carbon  undergoes  no  change.     Chloride  of  sulphur 
and  bichloride  of  phosphorus,  which  result  from  saturating  these  substances 
with  dry  chlorine,  are  devoid  of  acidity;  but  the  addition  of  water  converts 
the  one  into  muriatic  and  phosphorous  acid,  the  other  into  muriatic  and 
hyposulphurous  acid. 

887.  If  chlorine  be  muriatic  acid  oxygenated,  the  discovery  of  the  hypo- 
chlorous,  chlorous,  chloric,  and  oxychloric  acids  must  establish  this  ano- 
maly, that  the  radical  of  muriatic  acid,  by  successive  additions  of  the  same 
acidifying  principle,  gains,  loses,  and  regains  acidity,  forming  first  an  acid, 
then  an  oxide,  and  finally  four  acids.     I  have  said  it  forms  an  oxide,  be- 
cause chlorine  must  be  deemed  an  oxide,  having  no  acid  properties. 

888.  It  has  been  stated,  page  156,  that  Thenard  oxygenated  the  water  in 
liquid  muriatic  acid;  yet  this  did  not  convert  it  into  a  solution  of  chlorine. 

889.  Agreeably  to  the  doctrine  now  universally  sanctioned  by  chemists, 
chlorohydric  acid,  consisting  of  chlorine  and  hydrogen,  is   deprived  of 
hydrogen  in  all  those  processes  by  which  it  was  formerly  supposed  to  be 
oxygenated. 

Of  Bromohydric  Acid. 

890.  To  obtain  bromohydric  acid,  Berzelius  recommends  that  phospho- 
rus should  be  placed  in  contact  with  bromine  under  water.     The  resulting 
bromide  is  resolved  into  phosphoric  acid  and  bromohydric  acid  gas.     The 
latter  may  be  collected  over  mercury,  or  made  to  produce  liquid  bromohy- 
dric acid  by  union  with  water,  exactly  by  the  same  means  as  have  been  il- 
lustrated in  the  case  of  chlorohydric  acid,  which  the  bromohydric  acid  much 
resembles.     Bromohydric  acid  is  a  colourless  gas,  in  smell  similar  to  chlo- 
rohydric acid.     It  has  a  specific  gravity  of  2.7353.     When  brought  in  con- 
tact with  the  air  it  produces  thick  fumes.     It  is  decomposed  in  passing 
through  a  tube  heated  red-hot.     It  is  composed  of  one  atom  of  hydrogen 
and  one  of  bromine. 

Of  lodohydric  Acid. 

891.  According  to  Berzelius,  in  order  to  procure  iodohydric  acid,  nine 
parts  of  iodine  and  one  of  phosphorus  should  be  placed  in  contact  at  the  bot- 
tom of  a  tube  or  small  matrass,  and  protected  from  the  air  by  powdered 
glass.     Iodide  of  phosphorus  is  formed,  which  is  resolved  into  phosphoric 
acid  and  iodohydric  acid  gas  by  the  gradual  affusion  of  a  small  quantity  of 
water.     The  gas  cannot  be  collected  over  water  or  mercury,  as  it  acts  on 


166  INORGANIC,  CHEMISTRY. 

the  one  and  is  absorbed  by  the  other.  Hence  it  must  be  collected  in  bot- 
tles, by  means  of  tubes  descending  through  their  orifices  to  their  bottoms, 
which  is  analogous  to  the  mode,  already  illustrated  on  a  large  scale,  for  col- 
lecting chlorine.  (666.)  This  process  is  even  more  practicable  in  the  case 
in  point;  since  iodohydric  acid  is  the  heaviest  gas  known,  having  a  specific 
gravity  of  4.3854,  or  more  than  four  times  as  great  as  that  of  atmospheric 
air.  In  composition  and  general  properties  it  resembles  chlorohydric  and 
bromohydric  acid. 

892.  The  compound  of  hydrogen  with  fluorine,  forming  the  acid  of  fluor 
spar  or/uohydric  acid,  improperly  called  hydrofluoric  acid,  will  be  defer- 
red for  consideration,  until  boron  and  silicon  have  been  treated  of. 

COMPOUNDS  OF  HYDROGEN  WITH  SULPHUR. 

893.  It  appears   probable  that   hydrogen  and   sulphur 
may  combine   in   various   proportions.     Only   two   com- 
pounds, however,  have  been  sufficiently  distinguished,  to 
be  worthy  of  a  place  in  this  work.     One  of  these  is  a  defi- 
nite compound  of  hydrogen  and  sulphur,  containing  an  atom 
of  each,  and  has  hitherto  been  called  sulphuretted  hydro- 
gen, especially  by  the  British  chemists.     The  other  con- 
tains one  atom  of  hydrogen,  with  a  plurality  of  atoms  of 
sulphur,  which,  according  to  Thenard,  may  extend  to  the 
proportions  of  four,  six,  or  eight  atoms  to  one.     To  this 
he  has  accordingly  given  the  name  of  polysulphuret  of  hy- 
drogen. 

894.  Pursuant  to  the  nomenclature  of  Berzelius,  all  the 
electro-negative  compounds  of  sulphur  are  called  sulphides, 
and  are  designated  by  attaching,  as  an  adjective,  their  ra- 
dical, with  the  last  syllable  changed  into  ique  in  French,  or 
ic  in  English;  as,  for  instance,  sulphuretted  hydrogen  is 
called  by  him  in  French,  sulphide  hydrique,  which  in  Eng- 
lish is  rendered  by  hydric  sulphide.     This  gas  has  by  some 
chemists,  especially  the  French,  been  called  hydrosulphuric 
acid,  by  analogy  with  hydrochloric  acid.     The  term  hydro- 
sulphuric  is  objectionable  from  its  conveying  the  idea  of 
aqueous  sulphuric  acid ;  hydro  being  used  to  imply  the  pre- 
sence or  influence  of  water.     I  have  already  pointed  out 
the  inconsistency  of  designating  some  acids  by  giving  pre- 
cedence to  the  syllables  representing  their  radical,  as  in 
hydrochloric,  hydriodic;  while  in  others,  the  syllable  indi- 
cative of  their  electro-negative  ingredient  has  the  prece- 
dence, as  in  fluosilicic,  fluoboric,  chlorocarbonic,  and  chlo- 
rocyanic.     If  sulphuretted  hydrogen  is  to  receive  a  new 
name,  I  would  prefer  to  call  it  sulphydric  acid,  as  already 
suggested.  (858,  &c.) 


HYDROGEN.  167 

Of  Sulphydric  Acid  or  Sulphuretted  Hydrogen. 

895.  Few  persons  are  unacquainted  with  the  unpleasant 
odour  which  results  from  the  washings  of  a  gun  barrel, 
made  foul  by  the  explosion  of  gunpowder,  or  that  produced 
by  putrid  eggs.  This  odour  arises  from  a  compound  con- 
sisting of  one  atom  of  hydrogen  and  one  atom  of  sulphur. 
The  celebrated  sulphur  springs  of  Virginia  are  indebted  for 
their  odour,  and  mainly  for  their  efficacy,  to  this  compound ; 
to  which  the  celebrated  Thenard  has  given  the  name  of 
sulphydric  acid. 

896..  Preparation. — This  gas  is  copiously  evolved  by  the 
reaction  of  diluted  sulphuric  acid  with  sulphuret  of  iron. 
In  order  to  have  a  supply  of  it  at  command,  it  is  only  ne- 
cessary to  substitute  this  last  mentioned  substance  for  zinc 
in  the  self-regulating  apparatus  employed  for  hydrogen, 
already  described.  (706.) 

897.  As  it  is  absorbed  by  water  and  gradually  decom- 
posed by  mercury,  Berzelius  recommends  that  it  should  be 
received  over  brine.    Its  purity  is  demonstrated  by  its  com- 
plete absorption  by  a  solution  of  caustic  potash,  and  by  its 
not  rendering  lime-water  milky. 

898.  He  also  advises  that  the  gas  should  be  passed 
through  water,  as  otherwise  it  is  liable  to  be  contaminated 
by  the  generating  materials.     When  the  acid  is  sufficient- 
ly diluted,  the  action  in  the  apparatus  above  referred  to  is 
so  gentle,  that  I  am  confident  from  my  experience  that  the 
gas  comes  over  sufficiently  pure  for  ordinary  purposes. 

Convenient  Method  of  impregnating  Liquids  with  Sulphydric  Acid. 

899.  Suppose  the  little  flask,  F,  to  contain  the  liquid  to  be 
//  impregnated,  and  the  flexible  pipe,  one  end  of  which  is  inserted 
//  into  the  orifice  of  the  flask,  to  proceed  from  a  self-regulating  re- 
servoir of  sulphydric  acid  :  it  must  be  evident  that  the  gas,  flow- 
ing into  the  cavity  of  the  flask  from  the  orifice  of  the  pipe,  must 
enter  the  solution.  If  not  absorbed  as  rapidly  as  it  may  be  yield- 
ed, the  excess  must  bubble  up  through  the  solution  5  the  cork 
being  meanwhile  loosened  to  allow  the  atmospheric  air  to  es- 
cape. The  expulsion  of  the  atmospheric  air  having  been  com- 
pleted, and  the  cork  inserted  into  the  neck  of  the  flask,  so  as  to 
prevent  the  gas  from  escaping,  it  will  continue  to  enter  the 
flask  as  fast  as  absorbed.  But  if  it  be  generated  in  the  reservoir 
more  rapidly  than  the  solution  can  absorb  it,  the  excess  must 
remain  in  the  reservoir,  and  contribute  to  depress  the  acid  so 
low  in  the  bell-glass,  as  to  diminish  the  quantity  of  the  sul- 
phide on  which  it  can  act.  Finally,  when  the  solution  becomes 
saturated,  the  gas  generated  in  the  bell  must  fill  it,  and  thus, 
by  usurping  the  place  of  the  acid,  cause  its  reaction  with  the 
sulphide  of  iron  lo  be  suspended. 


168  INORGANIC  CHEMISTRY. 

900.  Properties. — Sulphydric  acid  is  a  permanent  gas 
with  the  odour  of  rotten  eggs,  absorbable  by  water,  inflam- 
mable and  explosive,  forming,  by  combustion  with  air  or 
oxygen  gas,  water,  and  a  mixture  of  sulphurous  and  sul- 
phuric acids. 

901.  At  the  temperature  of  50°  F.,  and  under  a  pressure 
of  17  atmospheres,  sulphydric  acid  becomes  a  colourless 
liquid  more  fluid  even  than  sulphuric  ether. 

902.  Metals  are  tarnished  by  it,  especially  preparations  of 
lead,  of  which  it  is  a  test,  and  by  which  it  may  be  detected. 
It  is  evolved  from  privies,  blackening  the  ceruse  or  carbo- 
nate of  lead  in  paint.     It  may  be  decomposed  by  various 
substances,  having  an  affinity  for  one  or  both  of  its  consti- 
tuents, as  for  instance,  by  chlorine,  potassium,  sodium,  sul- 
phurous acid,  and  ignited  carbon;  also  by  successive  elec- 
tric explosions. 

903.  Sulphydric  acid  decomposes  all  metallic  solutions,  ex- 
cept those  of  cobalt,  nickel,  iron,  zinc,  manganese,  titanium, 
and  molybdenum,  in  consequence  of  the  attraction  between 
hydrogen  and  either  oxygen  or  chlorine,  and  between  the 
metals  and  sulphur.     Metals,  which  in  the  metallic  state 
yield  hydrogen  during  their  reaction  with  diluted  sulphuric 
or  muriatic  acid,  afford  sulphydric  acid,  when  in  the  state 
of  a  sulphide  or  sulphuret,  subjected  to  those  acids.     Ac- 
cording to  Berzelius,  some  sulphides  act  as  acids,  others 
as  bases,  and  unite  with  each  other  in  a  manner  analogous 
to  that  in  which  the  oxacids  and  oxybases  combine.     The 
resulting  compounds  he  calls  sulpho-salts.    Some  sulphides 
are  liable  to  be  reduced  by  exposure  to  pure  hydrogen  in 
a  way  analogous  to  that  in  which  oxides  are  decomposed 
by  the  same  agent.     But  the  number  of  sulphides  which 
may  be  thus  decomposed  is  much  smaller.     Atmospheric 
air  is  said  to  be  rendered  deleterious  to  life  by  the  addition 
of  2-hrth  of  this  gas. 

904.  It  is  alleged  that  a  single  cubic  inch  of  the  gas, 
liberated  in  a  large  chamber,  will  in  every  part  be  produc- 
tive of  its  characteristic  unpleasant  odour.     A  current  of 
the  gas  directed  upon  the  tongue  causes  an  astringent, 
acid,  and  bitter  taste.     The  specific  gravity  of  sulphydric 
acid  is  1.1782,  that  of  atmospheric  air  being  1.     It  is 
slowly  decomposed  by  nitric  oxide,  and  by  sulphurous  acid 
when  moist.    Nitroso-nitric  acid  reacts  with  it  explosively. 
With  sulphurous  acid  when  dry  it  does  not  react;  but, 


HYDROGEN.  169 

water  being  present,  condensation  ensues  with  a  deposition 
of  sulphur,  and,  according  to  Thompson,  the  production  of 
a  peculiar  acid.  At  the  temperature  of  50°  F.,  water  takes 
up  three  times  its  bulk  of  sulphydric  acid,  which  may  be 
entirely  expelled  by  a  boiling  heat.  The  aqueous  solution 
reddens  litmus,  and  becomes  turbid  after  some  time  by  ex- 
posure to  the  air,  with  the  oxygen  of  which  the  hydrogen 
of  the  gas  combines,  while  the  sulphur  precipitates.  It  has 
already  been  stated  that  water  impregnated  with  sulphy- 
dric acid  exists  in  many  natural  springs,  which  are  much 
frequented  by  invalids. 

905.  The  celebrated  white  sulphur,  salt  sulphur,  and  red 
sulphur  springs  of  Virginia,  are  of  this  nature.     They  ap- 
pear particularly  efficacious  as  remedies  for  bilious  disor- 
ders, and  in  cutaneous  diseases. 

906.  The  red  sulphur  springs  are  thought  to  be  pecu- 
liarly useful  in  some  pulmonary  complaints,  and  appear  to 
have  a  surprising  and  unaccountable  influence  in  lowering 
the  frequency  and  force  of  the  pulse. 

Experimental  Illustrations. 

907.  Method    of  extricating    sulphydric    acid   gas   by 
means  of  a  self-regulating  reservoir  exhibited;   also,  the 
impregnation  of  water  with  it.     Effects  of  its  aqueous  so- 
lution on  litmus,  and  on  various  metallic  solutions.     Cha- 
racters written  with  dissolved  acetate  of  lead  are  black- 
ened by  exposure  to  the  gas,  or  its  aqueous  solution.     Its 
inflammation  by  nitric  acid. 

Sympathetic  Picture. 

908.  The  original  of  this  figure  (see  the  engraving  at  the  top  of  the  following 
page)  was  drawn  of  a  gigantic  size,  in  acetate  of  lead,  and  was  invisible  at  a  little 
distance,  until  a  jet  of  sulphuretted  hydrogen  was  directed  upon  it.  The  image 
then  appeared  by  the  waving  of  the  pipe  from  which  the  gas  flowed,  as  if  it  were 
the  wand  of  a  magician. 

ltd1.).  If  the  acetate  has  had  time  to  become  dry,  the  experiment  will  not  succeed 
without  restoring  a  due  degree  of  moisture.  This  object  is  best  accomplished  by 
passing  a  wet  sponge  over  the  back  of  the  sheet  on  which  the  figure  has  been 
drawn. 

910.  Rationale. — The  acetate  of  lead  consists 'of  acetic  acid  and  oxide  of  lead. 
The  oxygen  of  the  oxide  unites  with  the  hydrogen  of  the  gas,  while  the  sulphur 
and  lead  form  a  sulphuret,  to  which  the  blackness  of  the  picture  is  due. 


22 


170 


INORGANIC  CHEMISTRY, 


Of  the  Polysulphide  of  Hydrogen. 

911.  There  are  various  compounds  formed  by  sulphur  with  metals,  some 
of  which  are  soluble ;  as  for  instance  the  compound  formed  by  boiling  it 
with  lime.     This  compound  has  been  called  a  persulphuret  of  calcium.     I 
would  call  it  a  persulphide.     Scheele  ascertained  that  on  pouring  into  a  di- 
luted acid  a  persulphuret,  such  as  that  to  which  I  have  alluded,  an  oily 
looking  liquid  was  precipitated,  which  subsequently  received  the  name  of 
bisulphuretted  hydrogen.     Thenard  designates  this  compound  as  the  poly- 
sulphuret  of  hydrogen,  on  account  of  the  great  and  variable  number  of 
atoms  of  sulphur  which  enter  into  its  composition.     Moreover  he  alleges 
that  it  constitutes  a  compound  analogous  in  its  properties  to  the  deutoxide  of 
hydrogen ;  being  like  that  mysterious  combination  decomposable  by  many 
substances  for  which  it  has  no  affinity.     Even  the  presence  of  the  persul- 
phide employed  in  its  production  is  incompatible  with  its  existence,  and 
hence  the  impossibility  of  forming  it  by  pouring  the  acid  into  the  solution. 
In  that  case  an  excess  of  the  persulphide  must  inevitably  be  present. 

912.  He  alleges  that  the  polysulphuret  (polysulphide)  is  always  liquid  at 
ordinary  temperatures.     Its  colour  is  yellow,  sometimes  approaching  a 
greenish-brown.     It  whitens  the  tongue  when  applied  to  it,  as  is  the  case 
upon  making  a  similar  application  of  deutoxide  of  hydrogen.     The  same 
effect  is  produced  upon  the  skin.     Litmus  paper  is  bleached  by  it,  more 
especially  when  it  is  diffused  in  muriatic  acid.     Sometimes  it  has  the  con- 
sistency of  an  essential  oil,  sometimes  of  a  fat  oil,  according  to  the  propor- 
tion of  its  constituents,  which  has  already  been  stated  to  be  variable.     Its 
odour  is  peculiar  and  disagreeable,  especially  at  the  period  when,  having 
been  recently  formed,  the  supernatant  liquid  is  decanted  from  it.     Then 


HYDROGEN.  171 

also  it  affects  the  eyes  painfully.  Sooner  or  later  it  is  resolved  into  its 
elements  spontaneously.  Charcoal,  platinum,  gold,  iridium,  and  many 
other  metals  in  the  pulverulent  form,  cause  the  evolution  of  the  hydrogen. 
Many  metallic  oxides  have  the  same  effect,  some  so  actively  as  to  cause  a 
brisk  effervescence.  These  results  also  ensue  from  contact  with  the  deut- 
oxide  or  bioxide  of  manganese,  from  magnesia,  from  silica,  and  above  all 
from  pulverized  baryta,  strontia,  lime,  potash,  and  soda.  From  some  of 
the  facts  mentioned  by  Thenard,  I  infer  that  this  substance  may  be  of  great 
service  in  bleaching. 

COMPOUNDS  OF  HYDROGEN  WITH  SELENIUM  AND 
TELLURIUM. 

Of  Selenhydric  Acid,  commonly  called  Selenuretted  Hydrogen. 

913.  Selenhydric  acid  is  supposed  to  consist  of  one  atom  of  selenium, 
and  one  atom  of  hydrogen.    It  may  be  obtained  from  the  selenide  of  potas- 
sium or  of  iron,  by  the  action  of  chlorohydric  acid.     It  is  a  colourless  gas, 
absorbable  without  change  of  colour  by  water  which  has  been  boiled.    Water 
thus  impregnated  has  an  hepatic  taste,  reddens  litmus  paper,  and  if  applied 
to  the  skin,  stains  it  a  brownish-red.     The  solution  exposed  to  the  air,  by 
the  oxidation  of  the  hydrogen,  becomes  gradually  turbid  from  the  surface 
downwards,  acquiring  a  reddish  hue,  and  depositing  selenium  in  light  flocks. 
All  metallic  salts,  even  those  of  iron  and  zinc,  when  they  are  neutral,  are 
precipitated  by  selenhydric  acid.     The  precipitates  are  generally  of  a  deep 
black  colour,  yet  those  of  zinc,  manganese,  and  cerium,  are  flesh-coloured. 
By  the  oxidizement  of  the  hydrogen  in  selenhydric  acid,  selenium  is  pre- 
cipitated of  a  cinnabar-red  colour  on  any  moist  body.     This  acid  exercises 
upon  the  respiratory  organs  a  violent  action,  which  might  easily  become 
dangerous.     It  produces  at  first  the  odour  of  sulphydric  acid,  but  soon  after 
a  prickling  sensation  in  the  membranes  of  the  nostrils,  which  resembles  that 
created  by  fluosilicic  acid  gas,  but  is  more  stimulating.     Subsequently  the 
eyes  become  red,  and  the  sense  of  smell  is  paralyzed.     A  single  bubble  of 
the  gas,  received  into  the  nose,  caused  such  a  paralysis  of  the  olfactory 
nerves,  as  to  create  insensibility  even^to  the  fumes  of  the  strongest  ammo- 
nia.    The  power  of  detecting  odours  was  not  recovered  before  the  expira- 
tion of  five  or  six  hours. 

914.  Thenard  mentions  that  Berzelius,  in  consequence  of  inhaling  se- 
lenhydric acid  gas,  was  attacked  by  a  cough  so  severe,  that  a  blister  was 
deemed  necessary.     The  quantity  inhaled  was  so  minute  as  to  give  the 
impression,  that,  in  its  effects  upon  the  human  system,  this  gas  is  pre- 
eminently pernicious. 

Of  Telluhydric  Acid,  commonly  called  Telluretted  Hydrogen. 

915.  When  an  alloy  of  tellurium  with  zinc  or  tin  is  exposed  to  the  action 
of  chlorohydric  acid,  telluhydric  acid  is  evolved.     It  is  a  colourless  gas, 
which  strongly  resembles  sulphydric  acid  in  smell  and  in  its  chemical  and 
mechanical  properties.     It  reddens  litmus  paper,  is  soluble  in  water,  pro- 
ducing a  colourless  solution,  which  by  exposure  to  the  air  becomes  brown, 
in  consequence  of  the  oxidation  of  the  hydrogen  and  precipitation  of  the 
tellurium.     It  is  probably  composed  of  one  atom  of  hydrogen  and  one  of 
tellurium. 


172  INORGANIC  CHEMISTRY. 

916.  The  effect  of  the  monosyllable  gen,  in  chemical  language,  has  been 
explained.  (See  note,  628.) 


SECTION  II. 

OF  NITROGEN  OR  AZOTE. 

917.  In  the  gaseous  state,  it  forms  nearly  four-fifths  of 
the  atmosphere  in  bulk.    Its  ponderable  base  is  a  principal 
element  in  animal  substances.     In  vegetables,  it  is  only 
occasionally  found.     It  was  called  azote,  from  the  Greek 
£*>»>  life,  and  *,  privative  of.     It  was  subsequently  named 
nitrogen,  azote  being  equally  applicable  to  other  gases 
which  are  destructive  of  life.     I  regret  that  Thenard,  in- 
stead of  abandoning  the  use  of  this  bad  word,  has  lately 
endeavoured  to  give  it  a  further  hold  on  nomenclature,  by 
using  the  words  azotous  and  azotic,  in  lieu  of  nitrous  and 
nitric. 

918.  Consistently  with  the  explanation  which  has  been 
given  of  the  monosyllable  gen,  nitrogen  signifies  a  capacity 
to  produce  nitric  acid,  as  oxygen  conveys  the  idea  of  a 
capacity  to  produce  acids  generally. 

919.  Preparation.  —  Nitrogen  may  be  procured  by  the 
aid  of  any  substance  which  will,  in  a  close  vessel,  abstract 
oxygen  from  the  included  portion  of  the  atmosphere  ;  as, 
for  instance,  by  the  combustion  of  phosphorus,  or  by  iron 
filings  and  sulphur  moistened.     This  gas  may  also  be  ob- 
tained by  heating  muscular  flesh  in  a  retort  with  nitric 
acid  very  much  diluted.     When  obtained  by  means  of 
phosphorus,  a  minute  quantity  of  this  substance  remains 
in  solution  in  the  nitrogen  ;  when  extricated  by  the  action 
of  nitric  acid,  it  contains  a  small  portion  of  carbonic  acid. 
In  either  case  it  may  be  purified  by  washing  it  with  an 
alkaline  solution,  or  with  lime-water. 

920.  Another  method  of  obtaining  nitrogen  gas  is  to 
pass  chlorine  through  liquid  ammonia.  The  chlorine  unites 
with  the  hydrogen  of  the  ammonia,  while  the  nitrogen  is 
liberated.     Care  must  be  taken  to  have  the  ammonia  in 
excess,  otherwise  a  chloride  of  nitrogen  may  be  formed, 
which   is  capable  of  producing  the  most  violent  explo- 
sions. 

921.  When  the  chlorite  of  lime  (bleaching  salt)  is  min- 


Abstraction  of  Oxygen  from  Atmospheric  Air  by  Phosphorus, 


(Page  173.) 


NITROGEN.  173 

gled  with  muriate  of  ammonia  and  moistened,  nitrogen  is 
evolved.  For  this  purpose  Professor  Emmet  has  recom- 
mended the  boiling  of  nitrate  of  ammonia  upon  zinc. 

Apparatus  for  obtaining  the  Nitrogen  from  Atmospheric  Mr. 

922.  The  apparatus  represented  in  the  opposite  engraving  leaves  the  nitrogen  so 
situated,  as  to  be  drawn  easily  from  the  containing  vessel,  in  such  quantities  and  at 
such  times  as  may  be  desirable.     In  its  principal  parts,  it  does  not  differ  from  the 
gasometer  for  oxygen.  (617.)     It  is  provided  with  a  pipe,  p,  concentric  with  the  axis 
of  the  lower  vessel,  C,  surmounted  by  a  small  copper  cup.   The  pipe  in  question  de- 
scends perpendicularly  from  the  level  of  the  brim  of  the  vessel  to  the  bottom;  being 
soldered  into  a  hole  in  the  latter,  so  that,  the  bore  being  accessible  from  without,  the 
copper  cup  at  the  upper  end  may,  when  necessary,  be  touched  with  the  end  of  a  red- 
hot  iron  rod,  introduced  through  the  pipe  as  in  burning  phosphorus  in  oxygen. 
(654,  &c.) 

923.  The  inner  vessel  of  the  gasometer  consists  of  a  bell-glass,  B,  suspended  by  a 
cord  passing  over  a  wooden  gallows  with  suitable  pulleys.   The  bell  has  a  perforated 
neck  cemented  into  a  brass  cap,  furnished  with  a  female  screw  for  receiving  a  cock. 
To  this  cock  a  flexible  lead-pipe  is  attached  by  a  gallows  screw.     Upon  the  copper 
cup  a  sufficient  quantity  of  phosphorus  being  placed,  and  the  lower  vessel  adequately 
supplied  with  water,  the  bell-glass  is  suspended  within  the  lower  vessel,  as  is  usual 
with  gasometers,  and  allowed  to  descend  about  a  third  of  its  depth.    Meanwhile,  the 
cock  of  the  tube  being  open,  the  air  is  allowed  to  escape,  so  that  the  liquid  within 
and  without  the  bell-glass  may  be  on  a  level.     The  cock  being  in  the  next  place 
closed,  and  the  temperature  of  the  phosphorus  sufficiently  raised  to  make  it  take  fire 
by  touching  the  cup  with  the  extremity  of  an  iron  rod  previously  reddened  in  the 
fire,  a  brilliant  combustion  ensues.    As  soon  as  it  declines,  the  iron,  meanwhile  kept 
in  the  fire,  should  be  again  introduced,  in  order  to  sustain  the  combustion  till  all  the 
oxygen  is  absorbed. 

924.  When  the  air  in  the  bell-glass  is  completely  deoxidized,  which  may  be  known 
by  the  fumes  becoming  yellow,  the  residual  nitrogen  may  be  expelled  into  any  reci- 
pient at  pleasure,  through  the  flexible  pipe  attached  to  the  cock  for  that  purpose,  by 
depressing  the  bell  in  the  water. 

925.  Properties  of  Nitrogen  Gas. — As  a  gas,  it  is  distin- 
guished by  a  comparative  want  of  properties.   It  is  lighter 
than  oxygen  gas,  or  atmospheric  air.     It  supports  neither 
life  nor  combustion,  but  is  obviously  a  harmless  ingredient 
in  the  air. 

926.  The  affinity  of  nitrogen  for  caloric,  compared  with 
that  which  it  displays  for  other  substances,  appears  to  be 
peculiarly  great.     Hence  it  is  not  liable,  like  hydrogen  or 
oxygen,  to  enter  into  combination  with  other  matter,  so 
as  to  part  with  the  caloric  to  which  it  owes  its  existence 
as  a  gas ;  and  when  under  any  circumstances  it  does  enter 
into  combination,  it  seems,  more  than  almost  any  other 
substance,  to  carry  caloric  into  combination  with  it ;  be- 
ing, consequently,  an  ingredient  in  a  majority  of  the  most 
powerful  fulminating  compounds. 

927.  Nitrogen  has  been  suspected  by  some  chemists  to 
be  a  compound,  but  is  generally  considered  as  an  element. 
At  the  temperature  of  60°  F.,   100  cubic  inches  weigh 


174  INORGANIC  CHEMISTRY. 

30.1650  grains.     Its  specific  gravity,  comparatively  with 
air,  is  0.9727. 

Experimental  Illustrations  of  the  Properties  of  Nitrogen 

Gas. 

928.  A  portion  of  the  nitrogen,  obtained  as  above  de- 
scribed, being  introduced  into  a  bottle,  extinguishes  a  can- 
dle flame  when  introduced  into  it ;  but  being  mixed  with 
one-fourth   of  its  bulk  of  oxygen  gas,   the  effect  of  the 
mixture  in  supporting  flame  is  similar  to  that  of  atmosphe- 
ric air. 

OF  ATMOSPHERIC  AIR. 

929.  Atmospheric  air  is  a  mixture,  not  a  chemical  com- 
pound, of  oxygen  and  nitrogen  gas,  with  some  moisture 
and  carbonic  acid,  in  the  following  proportions. 

By  Measure.  By  Weight. 

Nitrogen  gas  77.5  -  75.55 

Oxygen  gas  21.  23.32 

Aqueous  vapour  1.42  -         -  1.03 

Carbonic  acid v  0.08  -  0.10 

100.00  100.00 

930.  The   average  of  a  great  number  of  experiments, 
made  with  my  eudiometers,  makes  the  proportion  of  oxy- 
gen 20.66  in  100  of  air. 

931.  In  addition  to  these  constituents,  it  is  alleged  that 
there  is  a  little  chlorohydric  acid  in  the  atmosphere,  in 
situations  in  the  neighbourhood  of  the  sea;  and  hence  it 
arises,  probably,  that  animals  far  inland,  show  a  much 
greater  avidity  for  common  salt,  a  compound  of  chlorine 
and  sodium,  than  those  existing  in  regions  bordering  on 
the  ocean.    This  avidity  seems  to  have  been  implanted  in 
order  to  supply  a  source  for  the  chlorohydric  acid,  which 
appears  to  be  requisite  to  the  powers  of  the  gastric  fluid. 

932.  It  has  been  made  a  question  whether  the  nitrogen 
and  oxygen  of  the  air  are  not  in  a  state  of  chemical  com- 
bination.    I  am  of  opinion  that  no  other  cause  of  union 
between  them  exists  than  that  which  is  known  to  produce 
the  equable  diffusion  of  heterogeneous  gaseous  particles 
among  each  other,  notwithstanding  the  difference  of  their 
specific  gravities. 


NITROGEN.  175 

933.  In  its  qualities  atmospheric  air  does  not  differ  from 
a  mixture.     Oxygen,  mingled  with  hydrogen  in  the  same 
proportion  in  which  it  is  mingled  with  nitrogen  in  the  air, 
has  been  found  to  support  animal  life  nearly  as  well. 

934.  The  mechanical  influence  of  the  atmosphere,  so  far 
as  it  appertains  to  chemistry,  has  been  sufficiently  illus- 
trated, (177,  &c.)     I  have  also  treated  of  its  capacity  to 
hold  moisture,  and  to  promote  and  produce  cold  by  eva- 
poration, (229,  &c.)     Some  additional  methods  of  analys- 
ing it,  will  be  mentioned  under  the  heads  of  nitric  oxide 
and  phosphorus. 

Eudiometrical  Analysis  of  the  Atmosphere. 

935.  While  on  the  subject  of  atmospheric  air,  the  eudiometrical  analysis 
of  it  becomes  necessarily  an  object  of  attention.     I  have  already  given  an 
engraving  and  description  of  a  large  eudiometer,  which  I  have  designated 
as  a  volumescope.     By  means  of  that  instrument  it  was  demonstrated,  that 
when  the  elements  of  water  are  mixed  in  the  gaseous  state  and  ignited, 
they  will  always  combine  in  the  proportion  of  two  volumes  of  hydrogen  to 
one  volume  of  oxygen.     It  follows  that,  if  any  gaseous  mixture  containing 
oxygen,  and  no  other  gas  capable  of  combining  with  hydrogen  or  oxygen, 
be  ignited  with  an  excess  of  hydrogen,  all  the  oxygen  will  be  condensed  into 
water,  and  may  be  estimated  as  equal  to  one-third  of  the  resulting  deficit. 
It  follows  also  that,  if,  to  a  gaseous  mixture  containing  hydrogen,  and  no 
other  gas  with  which  hydrogen  or  oxygen  can  combine,  an  excess  of  oxy- 
gen be  added  and  the  mixture  ignited,  all  the  hydrogen  will  be  condensed, 
and  will  in  quantity  equal  two-thirds  of  the  deficit.     Thus,  if  five  volumes 
of  atmospheric  air  and  three  of  hydrogen  be  introduced  into  the  volume- 
scope  and  ignited,  the  eight  volumes  will  be  reduced  to  rather,  less  than  five; 
of  course  a  little  more  than  three  volumes  will  have  been  condensed,  of 
which  one-third  is  oxygen.     In  five  volumes  of  atmospheric  air,  there  is, 
therefore,  somewhat  more  than  one  volume  of  oxygen.     By  the  volume- 
scope  the  excess  cannot  be  accurately  measured,  but  by  other  instruments 
which  I  have  contrived,  and  which  I  shall  proceed  to  describe,  great  accu- 
racy is  attainable.     I  am  the  more  particular  in  describing  my  apparatus  in 
the  Compendium,  that  I  may  not  be  under  the  necessity  of  occupying  the 
brief  time  allotted  to  my  lectures  with  such  descriptions. 

Of  the  Sliding-rod  Eudiometer. 

936.  I  have  constructed  some  eudiometers,  and  gas  measures,  in  which 
the  measurement  of  gas  is  effected  by  a  graduated  rod,  which  slides  into  or 
out  of  the  cavity  of  a  tube,  through  a  collar  of  leathers  soaked  in  lard,  and 
compressed  by  a  screw  so  as  to  be  perfectly  air-tight.     This  rod  is  em- 
ployed to  vary  the  capacity  of  the  tube,  and  at  the  same  time  to  be  a  mea- 
sure of  the  quantity  of  air,  or  of  any  other  gas,  consequently  drawn  in  or 
expelled.     About  one-third  of  the  tube  is  occupied  by  the  sliding-rod.     The 
remainder,  being  recurved,  and  converging  to  a  perforated  apex,  is  of  a  form 
convenient  for  withdrawing  measured  portions  of  gas  from  vessels  inverted 
over  water  or  mercury. 

937.  There  were  two  forms  of  the  sliding-rod  eudiometer;  one  designed 


176 


INORGANIC  CHEMISTRY. 


to  be  used  for  explosive  mixtures,  requiring  ignition;  the  other  in  analysis 
dependent  upon  the  absorbing  power  of  a  liquid  or  gas.  The  former  differs 
from  the  eudiometers  employed  by  European  chemists,  in  the  contrivance 
for  igniting  the  explosive  mixtures,  as  well  as  in  that  for  measuring  them, 
galvano  ignition  (335)  being  substituted  for  the  electric  spark. 

938.  I  shall  proceed  to  describe  a  sliding-rod  eudiometer,  for  the  analy- 
sis of  explosive  mixtures,  which  I  designate  as  aqueous,  because  water  is  the 
confining  liquid  employed  in  it. 

Aqueous  Sliding-rod  Hydro-oxygen  Eudiometer. 


W      W 

939.  This  cut  represents  a  hydro-oxygen  eudiometer,  in  which  the  measurements 
are  made  by  a  sliding-rod,  and  the  explosions  are  effected  by  the  galvanic  ignition 
of  a  platinum  wire. 

940.  In  the  instrument  represented  by  the  preceding  cut,  the  igniting  wire  is  sol- 
dered into  the  summits  of  the  two  brass  wires,  W  W,  which  pase  through  the  bottom 
of  the  socket  S,  parallel  to  the  axis  of  the  glass  recipient,  G,  within  which  they  are 
seen.     One  of  the  wires  is  soldered  to  the  socket.     The  other  is  fastened  by  means 
of  a  collar  of  leathers,  packed  by  a  screw,  so  that  it  has  no  metallic  communication 
with  the  other  wire,  except  through  the  filament  of  platinum,  by  which  they  are  visi- 
bly connected  above,  and  which  I  have  already  called  the  igniting  wire.     The  glass 
has  a  capillary  orifice  at  the  apex,  A,  which  is  closed  by  means  of  a  lever  and  spring 
(apparent  in  the  drawing,)  excepting  when  the  pressure  of  the  spring  is  counter- 
acted by  the  thumb  of  the  operator.     The  sliding-rod,  R,  is  accurately  graduated  to 
about  160  degrees. 

941.  Experience  has  shown  the  expediency  of  securing  the  valve  which  closes  the 
aperture  in  the  apex  of  the  instrument  from  the  possibility  of  leakage  during  explo- 
sions, by  means  of  an  iron  staple  with  a  screw,  represented  by  the  following  cut. 

This  fastens  upon  two  pivots,  one  of  which  is  inserted  on  each  side 
of  the  brass  socket,  S,  into  which  the  glass  recipient,  G,  is  cement- 
ed. The  staple  hinges  upon  these  pivots,  and  may  be  brought  into 
a  position  in  which  the  screw,  A,  being  immediately  over  the  valve, 
may  be  made  to  tighten  it;  or  the  staple  may  be  made  to  hang  down, 
so  as  not  to  be  in  the  way  when  the  instrument  is  to  be  charged. 
In  order  to  use  the  eudiometer,  it  must  be  full  of  water,  free  from 
air-bubbles,  and  previously  proved  air-tight;*  the  rod  being  in- 
troduced to  its  hilt,  and  the  capillary  orifice  open,  in  consequence 
of  a  due  degree  of  pressure  on  the  lever,  by  which  it  is  usually 
closed.  Being  thus  prepared  to  ascertain  the  proportion  of  oxygen 
in  the  air,  draw  the  rod  out  of  the  tube  till  100  ^aduations  are  visi- 
ble. A  bulk  of  air,  equivalent  to  the  portion  of  the  rod  thus  with- 

*  To  prepare  the  instrument  and  prove  it  to  be  in  order,  depress  the  glass  receiver 
below  the  surface  of  the  water  in  the  pneumatic  cistern,  the  capillary  orifice  being 


NITROGEN.  177 

drawn,  will  of  course  enter  at  the  capillary  opening;  after  which  the  lever  must  be 
allowed  to  close  it.  Introduce  the  receiver  into  a  bell  glass  of  hydrogen,  and.  open- 
ing the  orifice,  draw  out  the  rod  as  far  as  an  enlargement  upon  the  end  will  allow  it 
to  be  retracted.  This  arrestation  will  take  place  just  as  the  160th  graduation  becomes 
visible;  and  then,  in  addition  to  the  100  measures  of  air  previously  taken,  60  of  hy- 
drogen will  have  entered  ;  next  close  the  orifice,  and  withdraw  the  instrument  from 
the  water.  Apply  the  projecting  wires,  W  W,  severally  to  the  metallic  cups,  com- 
municating with  the  poles  of'  the  calorirnotor  represented  below* ;  then  move  the 
handle  so  as  to  cause  the  receptacle  holding  the  acid  to  rise  about  the  plates.  By 
the  consequent  ignition  of  the  wire,  the  gas  will  explode.  The  instrument  being 
plunged  again  into  the  water  of  the  pneumatic  cistern,  so  that  the  capillary  orifice, 
duly  opened,  may  be  just  below  the  surface,  the  water  will  enter  and  fill  up  the  va- 
cuity caused  by  the  condensation  of  the  gases.  The  residual  air  being  excluded  by 
the  rod,  the  portion  of  the  rod  remaining  without  the  tube,  will  be  in  bulk  equiva- 
lent to  the  deficit,  which  may  consequently  be  ascertained  by  inspecting  the  gradua- 
tion. I  have  performed  this  experiment  in  thirty  seconds.  • 

942.  If  oxygen  is  to  be  examined  by  hydrogen,  or  hydrogen  by  oxygen,  we  must 
of  course  have  a  portion  of  each  in  vessels  over  the  pneumatic  cistern,  and  succes- 
sively take  the  requisite  quantities  of  them,  and  proceed  as  in  the  case  of  atmos- 
pheric air. 

943.  Another  and  perhaps  more  accurate  mode  of  operating  with  this  instrument 
is,  by  means  of  one  of  the  volumeters,  (see  947,  953;)  to  make  a  mixture  of  the  dif- 
ferent gases,  in  due  proportion,  in  a  bell  glass.     Thus,  let  two  measures  of  atmosphe- 
ric air  be  added  to  one  of  hydrogen ;  then  on  taking  one  hundred  and  fifty  measures 
of  the  mixture  into  the  eudiometer,  there  will  be  the  same  quantity  of  each  gas,  as 
if  50  measures  of  hydrogen  and  100  of  air  had  been  taken,  as  above  described.     In 
order  to  ascertain  the  quantity  of  pure  oxygen  in  the  gas  from  nitre  or  manganese, 
one  measure  of  it  might  be  added  to  three  of  hydrogen.     Then  of  160  measures  of 
the  mixture,  which  might  be  taken  into  the  eudiometer,  40  would  consist  of  the  gas 
to  be  assayed,  and  120  of  hydrogen;  and  one-third  of  the  deficit,  caused  by  the  ex- 
plosion, would  be  the  quantity  of  pure  oxygen  in  the  40  measures. 

944.  If  hydrogen  were  to  be  assayed,  as,  for  instance,  the  gas  evolved  by  the  reac- 
tion of  diluted  sulphuric  acid  with  zinc,  (see  page  144,)  it  would  be  proper  to  take 
equal  parts  of  the  hydrogen  and  oxygen;  as  the  gas  which  is  not  to  be  analyzed 
must  always  be  in  excess.     Taking  then  160  measures  into  the  eudiometer,  two- 
thirds  of  the  deficit,  caused  by  the  explosion,  would  be  the  pure  hydrogen  in  80 
measures  of  the  gas  under  analysis.     For  the  last  mentioned  process  it  is  preferable 
to  have  upon  the  rod,  in  addition  to  the  scale  of  160  (942),  another  of  200  degrees, 
by  which  means  fifty  measures  of  oxygen,  or  100  measures  of  hydrogen,  maybe  ana- 
lysed.    In  this  way  the  per  centage  of  impurity  may  be  more  readily  perceived. 

945.  B  (see  the  preceding  figure)  represents  a  glass  with  wires  inserted  through 
small  tubulures,  in  the  usual  mode  for  passing  the  electric  spark,  should  this  method 
of  producing  ignition  be  deemed  desirable,  for  the  sake  of  varying  the  experiment, 
or  for  the  purpose  of  illustration.     This  glass,  the  other  being  removed,  may  be  fast- 
ened into  the  same  place.     The  wires  W  W,  may  remain,  but  should  be  of  such  a 
height  as  not  to  interfere  with  the  passage  of  the  electric  spark.     The  instrument  is 
operated  with,  as  usual,  excepting  the  employment  of  an  electrical  machine,  or  elec- 
trophorus,  to  ignite  the  gaseous  mixture.     For  the  travelling  chemist,  the  last  men- 
uppermost  and  open;   draw  the  rod  out  of  its  tube  and  return  it  alternately,  so  that, 
at  each  stroke,  a  portion  of  water  may  pass  in,  and  a  portion  of  air  may  pass  out. 
During  this  operation,  the  instrument  should  be  occasionally  held  in  such  a  posture, 
as  that  all  the  air  may  rise  into  the  glass  recipient,  without  which  its  expulsion  by 
the  action  of  the  rod  is  impracticable.     Now  close  the  orifice  at  the  apex,  A,  and 
draw  out  a  few  inches  of  the  rod,  in  order  to  see  whether  any  air  can  enter  at  the 
junctures,  or  pass  between  the  collar  of  leathers  and  the  sliding  rod.     If  the  instru- 
ment be  quite  air-tight,  the  bubbles,  extricated  in  consequence  of  the  vacuum  pro- 
duced by  withdrawing  the  rod,  will  disappear  when  it  is  restored  to  its  place. 

*  The  figure  represents  a  calorimotor,  containing  two  galvanic  pairs,  each  consist- 
ing of  two  plates 'of  zinc  and  three  of  copper,  severally  eight  inches  by  nine,  for  a 
particular  description  of  which,  see  my  Treatise  of  Galvanism  or  Voltaic  Electricity. 
Into  two  cavities  or  cups,  in  two  masses  of  soft  solder  which  constitute  the  poles  of 
the  instrument,  the  wires,  W  W,  of  the  eudiometer  are  forcibly  pressed  by  one  hand 
of  the  operator,  while  by  the  other  the  acid  is  made  to  act  upon  the  plates  through 
the  instrumentality  of  the  lever.  Instantaneously  on  the  ignition  taking  place,  the 
circuit  should  be  interrupted  by  lifting  the  eudiometer;  as  otherwise  the  wire  might 
be  fused. 

23 


178 


INORGANIC  CHEMISTRY. 


tioned  mode  of  ignition  may  be  preferable ;  because  an  electrophorus  is  more  porta- 
ble than  a  galvanic  apparatus. 

946.  In  damp  weather,  or  in  a  laboratory  where  there  is  a  pneumatic  cistern,  or 
amid  the  moisture  arising  from  the  respiration  of  a  large  class,  it  is  often  impossible 
to  accomplish  explosions  by  electricity. 

Sliding-rod  Gas  Measure. 

947.  The  construction  of  this  instrument,  represented  by  the  opposite  engraving, 
differs  from  that  of  the  sliding-rod  eudiometers,  in  having  a  valve  which  is  opened 
and  shut  by  a  spring  and  lever,  acting  upon  a  rod  passing  through  a  collar  of 
leathers.     By  means  of  this  valve,  any  gas  drawn  into  the  receiver,  is  included  so  as 
to  be  free  from  the  possibility  of  loss,  during  its  transfer  from  one  vessel  to  another. 
This  instrument  is  much  larger   than   the   sliding-rod   eudiometers  for  explosive 
mixtures;  being  intended  to  make  mixtures  of  gas,  in  those  cases  where  one  is  to 
be  to  the  other,  in  a  proportion  which  cannot  be  conveniently  obtained  by  taking 
more  or  less  volumes  of  the  one  than  of  the  other,  by  means  of  the  volumeters;  (948, 
954,)  for  instance,  suppose  it  were  an  object  to  analyze  the  air  according  to  Dr.  Thom- 
son's plan  of  taking  42  per  cent,  of  hydrogen.     The  only  way  of  mixing  the  gases  by 
a  volumeter  in  such  a  ratio,  would  be  to  take  the  full  of  the  volumeter  21  times  of 
hydrogen,  and  50  times  of  atmospheric  air.     By  the  large  sliding-rod  gas  measure 
this  object  is  effected  at  once,  by  taking  42  measures  of  the  one,  and  1UO  measures 
of  the  other. 

Piston  Valve  Volumeter. 

948.  I  have  contrived  some  instruments  for  measuring  gas  with  great  accuracy.    I 
call  them  volumeters  to  avoid  circumlocution.     They  are  of  two  kinds,  one  is  filled 
by  introducing  it  into  any  vessel  containing  the  gas  with  which  it  is  to  be  filled, 
over  water  or  mercury;  the  gas  is  introduced  into  the  other  through  an  orifice,  as  is 
usual  in  the  case  of  filling  a  common  bottle  over  the  pneumatic  cistern.     The  fol- 
lowing figure  will  convey  a  correct  idea  of  one  of  them,  which,  having  a  piston  and 
a  valve,  I  call  the  piston  valve  volumeter. 

949.  The  lever,  L,  is  attached  by  a  hinge  to  a  piston,  p,  which  works  inside  of  a 
chamber,  C.    The  rod  of  this  piston  extends  beyond  the  packing  through  the  axis 
of  the  bulb,  B,  to  the  orifice,  O,  in  its  apex,  where  it  supports  a  valve,  by  which 
this  orifice  is  kept  close,  so  long  as  the  pressure  of  the  spring,  acting  on  the  lever 
L,  is  not  counteracted  by  the  hand  of  the  operator. 

950.  Suppose  that,  while  the  bulb  of  this  instrument,  filled  with  water  or  mercury, 
is  within  a  bell  glass  containing  a  gas,  the  lever  be  pressed  towards  the  handle;  the 
valve  consequently  is  drawn  back,  so  as  to  open  the  orifice  in  the  apex  of  the  bulb, 
and  at  the  same  time  the  piston  descends  below  the  aperture,  A,  in  the  chamber. 

The  liquid  in  the  bulb  will  now  of  course 
escape,  and  be  replaced  by  gas,  which  is 
securely  included,  as  soon  as  the  pressure 
of  the  spring  is  allowed  to  push  the  piston 
beyond  the  lateral  aperture  in  the  cham- 
ber, and  the  valve  into  the  orifice,  O,  in 
the  apex  of  the  bulb. 

951.  The  gas,  thus  included,  may  be 
transferred  to  any  vessel,  inverted  over 
mercury  or  water,  by  depressing  the  ori- 
fice of  the  bulb  below  that  of  the  vessel, 
and  moving  the  lever,  L,  so  as  to  open 

//III*         /AW  t^ie  aPerture>  A,  in  the  chamber,  and  the 

orifice  of  the  bulb  simultaneously. 

952.  The  bulk  of  gas,  included  by  this 
volumeter,  will  always  be  the  same;  but 
the  quantity  will  be  as  the  density  of  the 
gas  into  which  it  may  be  introduced  when 
filled.     Hence,  in  order  to  measure  a  gas 
accurately,  the  liquid,  whether  water,  or 
mercury,  over  which  it  may  be  confined, 

A  ffilH  Ijj  /jj  should  be  of  the  same  height  within  as 

without.  This  is  especially  important 
in  the  case  of  mercury,  which,  being  in 

.^ ...,„,..„„ ^  weight  to  water  as  13.6  to  1,  affects  the 

density  of  a  gas  materially;  even  when 

its  surface  within  the  containing  vessel  does  not  deviate  sensibly  from  the  level  of  its 

surface  without. 


Sliding  Rod  Gas  Measure. 


(Page  178.) 


NITROGEN. 


179 


953.  To  remove  this  source  of  inaccuracy  I  employ  a  small  gauge,  which  commu- 
nicates, through  a  cock  in  the  neck  of  the  bell,  with  the  gas  within.  In  this  gauge 
any  light  liquid  will  answer,  wfcich  is  not  absorbent  of  the  gas.  In  the  case  of  am- 
monia,  liquid  ammonia  may  be  used ;  in  the  case  of  muriatic  acid  gas,  the  liquid 
acid.  The  gauge  is  simply  an  inverted  glass  syphon,  of  one  of  the  legs  of  which 
cavity  is  made  to  communicate  with  that  of  the  receiver,  holding  the  gas,  while  the 
other  is  open  to  the  atmosphere.  Even  mercury  may  be  used  in  such  an  instrument 
with  sufficient  accuracy,  because  the  legs  of  the  syphon  being  near  to  each  other, 
the  most  minute  disparity  in  the  heights  of  the  two  adjoining  columns  of  the  liquid 
occupying  the  syphon  will  be  discernible. 

Simple  Valve  Volumeter. 

954.  Besides  the  lower  orifice,  O,  by  which  it  is  filled 
with  gas,  the  volumeter  which  this  figure  represents,  has 
an. orifice  at  its  apex,  A,  closed  by  a  valve  attached  to  a 
lever.    This  lever  is  subjected  to  a  spring,  so  as  to  receive 
the  pressure  requisite  to  keep  the  upper  orifice  shut,  when 
no  effort  is  made  to  open  it. 

955.  When  this  volumeter  is  plunged  below  the  surface 
of  the  water  in  a  pneumatic  cistern,  the  air  being  allowed 
to  escape,  and  the  valve  then  to  shut  itself  under  the 
water,  on  lifting  the  vessel  it  comes  up  full  of  the  liquid, 
and  will  remain  so,  if  the  lower  orifice  be  ever  so  little 
below  the   surface  of  the  water   in   the   cistern.      Thus 
situated,  it  may  be  filled  with  hydrogen,  proceeding  by 
a  tube  from  a  self-regulating  reservoir.  (797,  798.)     If  the 
apex,  A,  be  then  placed  under  any  vessel,  filled  with 
water  and  inverted  in  the  usual  way,  the  gas  will  pass  into 
it  as  soon  as  the  valve  is  lifted. 

956.  Volumes  of  atmospheric  air  are  taken  by  the  same 
instrument,  simply  by  lowering  it  into  the  water  of  the 
cistern,  placing  the  apex  under  the  vessel  into  which  it  is 
to  be  transferred,  and  lifting  the  valve  :  or  preferably  by 
filling  it  with  water,  and  emptying  it  in  some  place  out  of 
doors,  where  the  atmosphere  may  be  supposed  sufficiently 
pure,  and  afterwards  transferring  the  air,  thus  obtained, 
by  opening  the  valve,  while  the  apex  is  within  the  ves- 
sel in  which  its  presence  is  required.     In  this  case,  while 
carrying  the  volumeter  forth  and  back,  the  lower  orifice 
must  be  closed.     This  object  is  best  effected  by  a  piece  of 

sheet  metal,  or  a  pane  of  glass.     It  is  necessary  that  the  water,  the  atmosphere,  and 
the  gases  should  be  at  the  same  temperature  during  the  process. 

CHEMICAL  COMPOUNDS  OF  NITROGEN  WITH  OXYGEN.  - 

957.  These  compounds  are  five  in  number,  nitrous  and 
nitric  oxide,  and  hyponitrous,  nitrous,  and  nitric  acid.  Their 
composition  is  given  in  the  following  table: — 


1  vol.  or  1 
atom  of  ni- 
trogen = 
14,   forms, 
with 


5  vol.  or  1  atom  oxygen,  1  vol.  nitrous  oxide. 

1  „    or  2  atoms      „        2  vols.  nitric  oxide. 
li  „    or  3       „          „       hyponitrous  acid. 

2  „    or  4      „          „        1  vol.  nitrous  acid. 

or  5      „  nitric  acid. 


Of  Protoxide  of  Nitrogen,  or  Nitrous  Oxide. 

958.  This  compound  does  not  exist  in  nature.     When 
artificially  obtained  it  is  gaseous;  yet  the  experiments  of 


180  INORGANIC  CHEMISTRY. 

Mr.  Faraday  have  taught  us  that  under  great  pressure,  it 
may  be  converted  into  a  liquid. 

959.  Preparation. — Nitrous  oxide  may  be  obtained  by 
the  action  of  dilute  nitric  acid  upon  zinc,  or  by  exposing 
nitric  oxide  gas  to  iron  filings,  sulphites,  or  other  sub- 
stances attractive  of  oxygen.  It  is  best  procured  by  sub- 
jecting nitrate  of  ammonia  to  heat,  and  receiving  the  pro- 
duct in  an  apparatus  described  in  the  following  article. 
As  pure  water  absorbs  this  gas,  Berzelius  receives  it  over 
a  saturated  solution  of  common  salt. 

Apparatus  for  evolving  and  collecting  Nitrous  Oxide. 

960.  This  apparatus  is  represented  by  the  opposite  engraving.    A,  is  a  copper  ves- 
sel of  about  eighteen  inches  in  height,  and  nine  inches  in  diameter,  which  is  repre- 
sented as  being  divided  longitudinally,  in  order  to  show  the  inside.     The  pipe,  B, 
proceeds  from  it  obliquely,  as  nearly  from  the  bottom  as  possible. 

961.  Above  that  part  of  the  cyliijder  from  which  the  pipe  proceeds,  there  is  a  dia- 
phragm of  copper,  perforated  like  a  colander.     A  bell  glass  is  surmounted  by  a  brass 
cock,  C,  supporting  a  tube  and  hollow  ball,  from  which  proceed  on  opposite  sides, 
two   pipes,  terminating  in  gallows  screws,  D  D,  for  the  attachment  of  perforated 
brass  knobs,  soldered  to  flexible  leaden  pipes,  E  E,  communicating  severally  with 
leathern  bags,  F  F,  of  suitable  dimensions. 

962.  The  beak  of  the  retort  must  be  long  enough  to  enter  the  cylinder,  so  that  the 
gas,  in  passing  from  the  mouth  of  the  beak,  may  rise  under  and  be  caught  by  the 
diaphragm.     This  is  made  concave  on  the  lower  side  so  as  to  cause  the  gas  to  pass 
through  the  perforations  already  mentioned,  which  are  all  comprised  within  a  circle 
less  in  diameter  than  the  bell  glass.     The  gas  is,  by  these  means,  made  to  enter  the 
bell  glass,  and  is,  previously  to  its  entrance,  sufficiently  in  contact  with  water,  to  be 
purified  from  the  acid  vapour  which  usually  accompanies  it.    On  account  of  this 
vapour,  the  employment  of  a  small  quantity  of  water,  to  wash  the  gas,  is  absolutely 
necessary ;  and  for  the  same  reason,  it  is  requisite  to  have  the  beak  of  the  retort  so 
long  as  to  convey  the  gas  into  the  water  without  touching  the  metal ;  otherwise  the 
acid  vapour  would  soon  corrode  the  copper  of  the  pipe,  B,  so  as  to  enable  the  gas  to 
escape.     But  while  a  small  quantity  of  water  is  necessary,  a  large  quantity  is  pro- 
ductive of  waste,  as  it  absorbs  its  own  bulk  of  the  gas.    On  this  account  I  contrived 
the  apparatus  here  described,  in  preference  to  using  gasometers  or  air-holders,  which 
require  larger  quantities  of  water. 

963.  The  furnace,  I,  is  so  contrived,  that  the  coals,  being  situated  in  a  drawer,  G, 
may  be  partially  or  wholly  removed  in  an  instant.     Hence  the  operator  is  enabled, 
without  difficulty,  to  regulate  the  duration  and  degree  of  the  heat.  This  control  over 
the  fire  is  especially  desirable  in  decomposing  the  nitrate  of  ammonia,  as  the  action 
otherwise  might  suddenly  become  so  violent  as  to  burst  the  retort.  The  iron  netting, 
represented  at  N,  is  suspended  within  the  furnace,  so  as  to  support  the  glass  retort, 
for  which  purpose  it  is  peculiarly  adapted.     The  first  portions  of  gas  which  pass 
over,  consisting  of  the  air  previously  in  the  retort,  are  allowed  to  escape  through  the 
cock,  H.     As  soon  as  the  nitrous  oxide  is  evolved,  it  may  be  detected  by  allowing  a 
jet  from  this  cock  to  act  upon  the  flame  of  a  taper. 

964.  To  obtain  good  nitrous  oxide  gas,  it  is  not  necessary  that  the  nitrate  of  am- 
monia should  be  crystallized  ;  nor  does  the  presence  of  a  minute  quantity  of  muriatic 
acid  interfere  with  the  result.     I  have  employed  advantageously,  in  the  production 
of  this  gas,  the  concrete  mass  formed  by  saturating  strong  nitric  acid  with  carbonate 
of  ammonia. 

965.  The  saturation  may  be  effected  in  a  retort,  and  the  decomposition  accom- 
plished by  exposing  the  compound  thus  formed  to  heat,  without  further  preparation. 

966.  Rationale  of  the  Process. — Nitrate  of  ammonia  consists  of  nitric 
acid  and  ammonia;  nitric  acid,  of  five  atoms  of  oxygen  and  one  of  nitro- 
gen; and  ammonia,  of  one  atom  of  nitrogen  and  three  atoms  of  hydrogen. 


1 


(Page  180.) 


Combustion  of  Phosphorus  in  Nitrous  Oxide. 


(Page  181.) 


NITROGEN.  181 

In  one  atom  of  this  salt,  five  atoms  of  oxygen,  three  of  hydrogen,  and  two 
of  nitrogen  are,  therefore,  present.  It  must  be  evident  that  if,  in  conse- 
quence of  the  heat,  each  atbm  of  hydrogen  takes  one  of  oxygen,  there  will 
be  but  one  atom  of  oxygen  left  for  each  atom  of  nitrogen.  Hence,  the 
whole  of  the  salt  is  resolved  into  water,  and  protoxide  of  nitrogen  or  ni- 
trous oxide. 

967.  Properties  of  Nitrous  Oxide. — It  is  a  permanent 
gas.     100  cubic  inches  weigh  47.25  grains.     It  supports 
the  combustion  of  a  candle  flame  vividly ;  though  nitric 
oxide  gas,  containing  twice  as  much  oxygen,  extinguishes 
flame.     Phosphorus  is  difficult  to  inflame  in  it,  but  burns 
with  rapidity  when  once  on  fire.     The  habitudes  of  sul- 
phur are  in  this  respect  analogous  to  those  of  phospho- 
rus.    An  iron  wire  burns  in  it  nearly  as  well  as  in  oxygen 
gas.  Most  of  the  combustible  bodies  burn  in  nitrous  oxide. 
When  ignited  with  hydrogen,  an  explosive  reaction  en- 
sues, and  water  and  nitrogen  result.     It  has  no  attribute 
of  acidity.     When  respired  it  stimulates  and  then  destroys 
life.     Its  effects  on  the  human  system,  when  breathed,  are 
analogous  to  a  transient,  peculiar,  various,  and  generally 
very  vivacious  ebriety.     It  is  much  more  rapidly  and  ex- 
tensively soluble  in  water  than  oxygen.     Homberg's  pyro- 
phorus,  or  that  which  I  have  contrived  to  obtain  from 
Prussian  blue,  takes  fire  on  falling  through  the  gas.  Agreea- 
bly to  the  researches  of  Faraday,  to  the  results  of  which 
allusion  has  been  made,  when  nitrate   of  ammonia  was 
heated  at  one  end  of  a  sealed  recurved  tube,  nitrous  oxide 
was  condensed  into  a  liquid  at  the  other  end. 

Experimental  Illustrations. 

968.  The  process  and  apparatus  for  producing,  collect- 
ing, and  breathing  nitrous  oxide  gas,  exhibited.     The  ef- 
fect on  a  lighted  candle  and  on  an  iron  wire,  shown. 

Combustion  of  Phosphorus  in  Nitrous  Oxide. 

969.  There  is  a  singular  indisposition  in  the  oxides  of  nitrogen  to  part 
with  their  oxygen  to  phosphorus,  until  it  be  intensely  ignited  either  by  an 
incandescent  iron,  or  by  the  access  of  uncombined  oxygen. 

970.  This  characteristic  in  the  case  of  nitrous  oxide,  may  be  illustrated 
by  means  of  an  apparatus,  like  that  employed  for  the  combustion  of  phos- 
phorus in  oxygen,  and  of  which  the  opposite  engraving  is  a  representation. 
It  consists  of  a  tall  cylindrical  receiver,  and  a  tube  descending  through  the 
neck  and  along  the  axis  of  the  receiver,  terminating  in  a  capillary  orifice 
over  the  cup  for  holding  the  phosphorus.     The  upper  end  of  the  tube,  out- 


182 


INORGANIC    CHEMISTRY. 


side  the  receiver,  is  furnished  with  a  cock,  to  which  a  gum-elastic  bag  in- 
flated with  oxygen  is  attached. 

971.  Under  these  circumstances,  the  receiver  having  been  exhausted  and 
filled  with  nitrous  oxide,  phosphorus,  previously  placed  within  the  cup,  may 

'be  melted  without  taking  fire.  But  as  soon  as  the  cock  communicating 
with  -the  bag  of  oxygen  is  opened,  an  intense  combustion  ensues ;  since  the 
oxygen,  emitted  in  a  jet  from  the  capillary  orifice  of  the  tube,  reaches  the 
melted  phosphorus,  and  excites  it  into  active  combustion,  which  the  nitrous 
oxide  afterwards  sustains  with  great  energy. 

Of  Nitric  Oxide,  formerly  called  Nitrous  Air. 

972.  This  oxide  is  an  artificial  product,  and  is  obtained 
only  in  the  gaseous  state.     Its  tendency  to  combine  with 
oxygen  renders  it  impossible  for  it  to  exist  where  the  at- 
mosphere has  access. 

973.  Preparation. — Nitric  oxide  is  evolved   during  the 
reaction  between  nitric  acid,  and  copper,  silver,  and  other 
metals. 

Self-regulating  Apparatus  for  generating  Nitric  Oxide. 

974.  The  command  of  a  sufficient  supply  of 
nitric  oxide  is  most  conveniently  attained  by 
means  of  a  self-regulating  apparatus,  made  in 
the  manner  which  I  am  about  to  describe. 

975.  A  vessel,  perforated  at   the   foot,   in 
other  respects  resembling  a  decanter ;  and  hav- 
ing a  long  neck,  surmounted  by  an  air-tight 
cap,  cock  and  gallows  screw,  is  placed  within 
a  glass  jar  of  suitable  dimensions,  as  repre- 
sented in  the  adjoining  figure.     By  means  of 
the  gallows  screw,  a  flexible  leaden  pipe  is  so 
attached,  as  to  form  a  communication  with  the 
bore  of  the  cock.      The  cavity  of  the  bottle 
being  supplied  with  copper  shreds  or  turnings, 
and  the  jar  with  diluted  nitric  acid,  by  the  re- 
action of  the  metal  with  the  acid,  gas  is  co- 
piously evolved,  producing  red  fumes  by  gene- 
rating nitrous  acid  with  the  oxygen  of  the  air. 
The  emission  of  the  gas  should  be  permitted 
until  the  red  fumes  disappear.     The  cock  may 
then  be  closed,  unless  it  be  desirable  to  allow 
the  gas  to  be  transferred  to  another  vessel. 

976.  It  should  be  understood  that  the  acid  passes  into  and  out  of  the  bot- 
tle, through  the  perforation  in  the  stem;  while  by  means  of  a  fragment  of 
glass,  the  metallic  shreds  are  prevented  from  escaping. 

977.  Properties. — Nitric  oxide  is  colourless,  permanent- 
ly elastic,  and  rather  heavier  than  air.  By  water  it  is  but 
slightly  absorbed.  It  is  not  acid.  It  extinguishes  a  can- 
dle flame,  but  ignites  Homberg's  pyrophorus,  and  supports 


NITROGEN.  183 

the  combustion  of  phosphorus,  if  inflamed  before  immer- 
sion in  it,  or  aided  by  the  access  of  a  minute  quantity  of 
oxygen.  It  is  fatal  to  animals,  renders  the  flame  of  hydro- 
gen green  by  mixture,  does  not  explode  with  it,  but  ex- 
plodes with  ammonia.  It  unites  rapidly  with  oxygen  gas, 
the  oxygen  of  the  air,  or  of  any  other  gaseous  mixture, 
producing  remarkable  red  acid  furnes. v  It  is  absorbed  by 
the  green  sulphate  and  the  protochloride  of  iron.  The 
solution  acquires  the  property  of  absorbing  oxygen,  and  is 
therefore  used  in  eudiometry.  Nitric  oxide  is  decomposed 
by  moistened  iron  filings;  also  by  ignited  charcoal,  arse- 
nic, zinc,  and  potassium. 

Experimental  Illustrations  of  the  Properties  of  Nitric  Oxide. 

978.  Copper  or  silver  being  subjected  to  nitric  acid,  ni- 
tric oxide  gas  is  extricated,  and  collected  in  bell  glasses 
over  water  or  mercury. 

979.  Absorption  of  nitric  oxide  gas  by  protochloride,  and 
protosulphate,  of  iron,  shown:  also  the  method  of  ascer- 
taining its  purity  by  the  sliding-rod  eudiometer;  and  its 
application  to  eudiometry,  in  various  ways,  by  means  of 
that,  and  other  eudiometrical  instruments. 

980.  Self-regulating  reservoir  of  nitric  oxide  gas  for  eu- 
diometrical experiments.      Absorption  of  oxygen  gas  by 
nitric  oxide,  and  the  consequent  acidity,  made  evident  by 
the  effect  on  litmus.     Pyrophorus  in  falling  through  the 
gas  is  ignited. 

Of  Hyponitrous  Acid. 

981.  This  acid  was  isolated  in  the  following  manner  by  Dulong.     Hav- 
ing subjected  a  mixture  of  four  volumes  of  nitric  oxide  with  one  of  oxygen, 
in  a  tube,  to  a  freezing  mixture,  he  obtained  the  acid  in  question  in  the 
form  of  a  deep  green  liquid  so  volatile  as  to  be  converted  into  a  red  vapour, 
unless  restrained  by  intense  cold.     The  hyponitrous  acid,  thus  procured,  is 
partially  decomposed  by  water  into  nitric  oxide  which  escapes ;  while  the 
oxygen,  combining  with  another  portion  of  the  hyponitrous  acid,  forms 
nitric  acid.     This  unites  with  the  water,  and  protects  the  remainder  of  the 
hyponitrous  acid  from  decomposition.     According  to  Berzelius,  it  is  formed, 
in  combination  with  bases,  when  nitrates  are  kept  at  a  red  heat  for  some 
time.     It  is  alleged  that  a  hyponitrite  of  lead  is  produced,  when  nitrate  of 
lead  is  boiled  with  metallic  lead. 

982.  Hyponitrous  acid,  when  isolated,  does  not  combine  directly  with 
bases,  but  is  resolved  by  contact  with  them  into  a  nitrate  and  nitric  oxide 
gas.     Nevertheless  it  may  be  transferred  from  one,  base  to  another.     It  is 


184  INORGANIC  CHEMISTRY. 

alleged  to  form  a  crystalline  compound  with  sulphuric  acid,  and  to  combine 
with  nitric  acid ;  but  it  is  questionable  whether,  in  combining  with  nitric 
acid,  it  is  not  resolved  into  nitric  oxide  and  nitric  acid.  As  an  ingredient 
in  one  of  the  ethereal  compounds  formed  by  the  reaction  of  nitric  acid  with 
alcohol,  this  acid  appears  to  have  some  practical  importance.  Of  the  ether 
thus  formed  it  would  be  premature  to  treat,  until  the  subject  of  etherifica- 
tion  is  undertaken. 

Of  Nitrous  Acid. 

983.  This  combination  may  be  procured  in  the  gaseous  state,  by  mix- 
ing two  volumes  of  deutoxide  of  nitrogen,  and  one  of  oxygen;  or  by  sub- 
jecting fuming  nitric  acid  to  heat,  and  collecting  the  product  in  a  receiver. 
It  is  also  procured  by  distilling  nitrate  of  lead.     Moist  nitrous  acid  is  a  gas 
of  a  deep  red  colour.     When  anhydrous,  it  is  a  liquid  of  an  orange-yellow 
which  boils  at  72°.     In  this  form  it  may  be  obtained  by  passing  deutoxide 
of  nitrogen  and  oxygen,  both  previously  dried,  through  a  tube  filled  with 
fragments  of  porcelain;  or  by  desiccating  the  nitrate  of  lead  before  employ- 
ing it  as  above  mentioned. 

984.  As  the  compound,  consisting  of  one  atom  of  nitrogen  and  four 
atoms  of  oxygen,  called  nitrous  acid  by  the  chemists  of  Great  Britain,  is 
decomposed  when  presented  to  bases,  Berzelius  does  not  regard  it  as  a  dis- 
tinct acid :  but  gives  the  name  in  question,  to  the  trioxide  of  nitrogen,  (756,) 
called  hyponitrous  acid  by  the  British  chemists. 

985.  The  tall  receiver  and  the  pear-shaped  vessel  in  its  vicinity,  being  filled  with 
water,  and  placed  upon  the  shelf  of  the  hydro-pneumatic  cistern,  (609,  &c.)  as  repre- 
sented in  the  engraving,  by  means  of  cocks  with  gallows  screws,  and  a  leaden  pipe, 
properly  attached,  render  it  practicable  to  make  between  them  a  communication  at 
pleasure. 

986.  These  preparations  being  made,  allow  the  pear-shaped  vessel,  which  I  will 
call  a  volumeter,  to  be  twice  filled  with  nitric  oxide,  and  as  often  allowed  to  yield  up 
its  contents  to  the  receiver.     Then  fill  the  volumeter  with  oxygen  gas.    In  the  next 
place,  open  the  communication  again  with  the  receiver.     The  oxygen,  passing  into 
the  nitric  oxide,  produces  dense  fumes  of  nitrous  acid.     At  first,  in  consequence  of 
the  rise  of  temperature  which  attends  the  combination,  there  appears  some  expan- 
sion; but  a  speedy  absorption  of  the  nitrous  acid  generated,  causes  the  water  to  rise, 
and  nearly  fill  the  receiver.     From  some  hidden  cause,  I  have  never  been  able  to 
attain  a  complete  condensation  by  this  process,  however  pure  might  be  the  gaseous 
materials  employed. 

Application  of  Nitric  Oxide  Gas  to  Eudiometry. 

987.  The  property  which  this  substance  has  of  forming  with  oxygen,  nitrous  or 
hyponitrous  acid,  either  of  which  is  absorbed  by  water,  has  caused  it  to  be  used  in 
eudiornetrical  operations;  but  owing  to  the  variable  proportions  in  which  the  above- 
mentioned   compounds  are   liable   to   be  formed,  the   results  obtained   have   been 
deemed  uncertain,  and  the  directions  for  using  nitrous  oxide,  given  by  such  emi- 
nent chemists  as  Dalton,  Gay-Lussac,  and  Thomson,  are  at  variance.     Gay-Lussac 
gave  an  empirical  formula,  agreeably  to  which  one-fourth  of  the  condensation,  pro- 
duced by  a  mixture  of  equal  parts  of  atmospheric  air  and  nitric  oxide,  is  to  be  as- 
sumed as  the  atmospheric  oxygen  present. 

988.  As  in  two  volumes  of  nitric  oxide,  a  volume  of  nitrogen  is  combined  with 
one  volume  of  oxygen,  occupying  the  same  bulk  as  if  merely  mingled, — to  convert 
the  nitric  oxide  into  nitrous  acid,  which  consists  of  the  same  quantity  of  nitrogen 
with  two  volumes  of  oxygen,  one  volume  of  oxygen  must  be  added.     Of  course,  if 
nitrous  acid  be  the  product,  one-third  of  the  deficit  produced,  would  be  the  quantity 
of  atmospheric  oxygen  present.     This  would  be  too  much  to  correspond  with  the 
formula  of  Gay-Lussac. 

989.  Supposing  hyponitrous  acid  produced,  only  half  as  much  oxygen  would  be 
required  as  is  necessary  to  produce  nitrous  acid;  so  that  instead  of  the  two  volumes 
of  nitric  oxide  taking  one  volume,  they  would  take  only  half  a  volume.     The  ratio  of 
|  in  2.J,  is  the  same  as  I  in  5,  or  one-fifth,  which  is  too  little  for  Gay-Lussac's  rule. 

900.  The  formula  recommended  by  Dr.  Thomson,  agreeably  to  which  one-third  of 


Synthesis  of  Nitrous  Acid. 


(Page  184.) 


Volumescopefor  the  Analysis  of  Atmospheric  Air  by  Nitric  Oxide. 


(Page  185.) 


NITROGEN.  185 

the  deficit  is  to  be  ascribed  to  oxygen,  is  perfectly  consistent  with  the  theory  of  vo- 
lumes, and  much  more  consonant  with  the  results  of  my  experiments  than  that  re- 
commended by  the  celebrated  author  of  that  admirable  theory. 

!>!>!.  The  late  Professor  Dana  ingeniously  reconciled  Gay-Lussac's  statement  with 
the  theory  of  volumes,  by  suggesting  that  half  a  volume  of  oxygen  may  take  one 
volume  of  the  nitric  oxide,  and  another  half  volume  of  oxygen,  two  volumes. 

vol.  vol. 

J  oxygen  takes  1  oxide  and  forms  nitrous  acid. 
£  oxygen  2  oxide  and  forms  hyponitrous  acid. 

1  3 

992.  The  total  condensation  here  would  be  four  volumes,  and    the  deficit  due  to 
oxygen  is  one  volume,  or  one-fourth. 

993.  With  the  deference  due  to  a  chemist  so  distinguished  as  the  author  of  the 
formula  in  question,  1  long  strove  unsuccessfully  to  verify  his  statements.  Agreeably 
to  a  great  number  of  experiments,  annually  repeated  during  many  years  with  differ- 
ent instruments,  it  has  been  found  that,  when  three  volumes  of  nitric  oxide  are  mix- 
ed, over  water,  with  five  of  atmospheric  air,  nearly  the  same  condensation  is  effected, 
as  when  like  quantities  of  air  and  hydrogen  are  ignited  together.     In  order  to  de- 
monstrate the  truth  of  this  allegation  to  my  numerous  class  of  pupils,  I  have  em- 
ployed the  apparatus  represented  by  the  opposite  engraving,  and  described  in  the 
following  article.     In  this  the  volumes  employed  are  so  large  as  to  make  the  results 
strikingly  evident  to  the  most  remote  observer. 

Volumescope  for  the  Analysis  of  Atmospheric  Mr  by  Nitric  Oxide. 

994.  Secured  in  a  screw  rod  and  plate  frame,  (248,)  there  is  a  glass  cylinder  thirty 
inches  in  height,  and  about  five  inches  in  diameter.     Into  the  brass  plate  which 
closes  it  at  top,  three  cocks  are  inserted,  each  provided  with  a  gallows  screw.     By 
means  of  a  flexible  leaden  pipe,  let  one  of  the  cocks  be  make  to  communicate  with 
an  air  pump.     Let  the  other  cock,  by  like  means,  be  made  to  communicate  with  a 
pear-shaped  glass  vessel,  which  acts  as  a  volumeter,  or  volume  measurer.     Let  the 
cylinder,  by  means  of  scales  placed  on  each  side  of  it,  be  graduated  so  as  to  hold 
eight  volumes,  any  three  of  which  shall  be  equivalent,  collectively,  to  the  contents 
of  the  volumeter.     The  apparatus  being  thus  prepared,  and  secured  over  one  of  the 
wells  of  the  pneumatic  cistern,  (613 ,)  exhaust  the  cylinder  by  means  of  the  air  pump, 
so  as  to  cause  the  water  to  rise  in  it,  until  by  the  scale  only  five  volumes  of  atmos- 
pheric air  are  left,  and  then  open  a  communication  with  the  volumeter.     The  air 
contained  in  this  vessel  will  then  pass  into  the  cylinder,  consequently  the  water  will 
subside  to  the  division  upon  the  scale  which  designates  eight  volumes,  thus  showing 
that  the  capacity  of  the  volumeter  is  equivalent  to  three  volumes  as  premised.  Next, 
by  means  of  the  pump,  raise  the  water  again  to  the  division  upon  the  scale,  marking 
five  volumes,  and  fill  the  volumeter  with  nitric  oxide.  If,  under  these  circumstances, 
the  communication  between  the  pear-shaped  vessel  and  the  cylinder  be  re-established, 
the  nitric  oxide  will  pass  into  the  cylinder,  and,  combining  with  the  oxygen  of  the 
contained  air,  will  produce  nitrous  acid  in  red  fumes,  which  the  water  will  absorb 
rapidly  at  first.     This  absorption  is  promoted  and  completed  by  jets  of  water,  pro- 
jected vertically  through  the  mingled  gases,  by  means  of  the  recurved  pipe,  and 
gum  elastic  bag  to  which  it  is  attached.     It  has  been  shown  by  the  preceding  part  of 
the  process,  that  the  contents  of  the  volumeter,  added  to  five  of  air,  would  make 
eight  volumes,  were  there  no  absorption;  but  the  actual  residue,  when  the  experi- 
ment is  well  performed,  is  always  a  little  less  than  five  volumes,  indicating  that  a 
little  more  than  one  volume  of  oxygen  is  contained  in  the  five  volumes  of  air  em- 
ployed, and  that  this  is  condensed  by  combining  with  twice  its  bulk  of  nitric  oxide. 
The  nitrous  acid,  usually  thus  called,  consists  of  one  volume  of  nitrogen  and  two 
volumes  of  oxygen.     Of  course,  to  convert  into  this  acid,  nitric  oxide,  consisting  of 
one  volume  of  nitrogen  and  one  volume  of  oxygen  uncondensed,  one  volume  of 
oxygen  must  be  added. 

Aqueous  Sliding-rod  Eudiometer  for  the  Analysis  of  Gaseous  Mixtures  by  Absorption. 

995.  The  form  of  the  sliding-rod  eudiometer  represented  in  the  next  figure  does 
not  differ  from  that  for  inflammable  mixtures,  (940,)  as  respects  the  mechanism  by 
which  the  rod  is  secured,  or  the  graduation,  which  it  is  convenient  to  have  exactly 
alike  in  both.     The  modification  "which  I  am  about  to  consider  I  found  very  ser- 
viceable in  the  analysis  of  gaseous  mixtures,  containing  carbonic  acid  gas.  or  for 

24 


186 


INORGANIC  CHEMISTRY. 


ascertaining  the  purity  of  nitric  oxide  gas  by  the  aid  of  protosulphate  of  iron.  It 
may  also  be  applied  to  the  analysis  of  the  atmosphere  by  nitric  oxide,  agreeably  to 
the  process  which  I  shall  forthwith  describe. 


996.  The  receiver,  represented  in  the  following  cut,  shaped  like  the  small  end  of 
an  egg,  is  employed  in  these  experiments,  being  mounted  so  as  to  slide  up  and  down 
upon  a  wire. 


997.  Being  filled  with  water,  and  immersed  in  the  pneumatic  cistern,  the  apex, 
A,  being  just  even  with  the  surface  of  the  water, — by  drawing  out  the  rod  of  the 
eudiometer,  take  into  the  tube  100  measures  of  atmospheric  air,  and  transfer  it  to 
the  receiver.     Next  take  50  measures  of  nitric  oxide  from  a  bell  as  above  described, 
and  add  it  to  the  air  in  the  receiver.     Wash  the  mixture  by  a  jet  of  water,  which 
is  easily  produced  from  the  apex  of  the  instrument,  and  draw  the  whole  of  the 
residual  gas  into  the  tube,  continuing  to  draw  out  the  rod  until  150  graduations 
appear.     In  the  next  place,  eject  the  residual  gas  from  the  instrument:  the  number 
of  graduations  of  the  rod  which  remain  on  the  outside  of  the  tube,  shows  the  deficit 
produced  by  the  absorption  of  the  oxygen  and  nitric  oxide,  in  the  state  of  nitrous 
acid. 

998.  In  a  great  number  of  experiments,  I  have  found  the  deficit  to  agree  very 
nearly  with  that  produced  by  the  explosion  of  the  same  quantity  of  air  with  hydro- 
gen, in  the  aqueous  sliding-rod  hydro-oxygen  eudiometer;  but  upon  the  whole  it  is 
rather  greater. 

Method  of  ascertaining  the  Purity  of  Nitric  Oxide  by  means  of  a  Solution  of  Protochlo- 
ride,  or  Protosulphate  of  Iron. 

999.  The  purity  of  nitric  oxide  is  easily  ascertained  by  means  of  a  solution  of 
protochloride,  or  green  sulphate  of  iron,  and  the  sliding-rod  eudiometer  above  de- 
scribed.    A  small  bottle  being  filled  with  a  solution  of  the  salt,  and  inverted  upon 
the  shelf  of  the  hydro-pneumatic  cistern,  take  into  the  eudiometer  one  hundred  mea- 
sures of  the  gas,  and  transfer  them  to  the  bottle,  which  must  be  agitated  for  two  or 
three  minutes.     The  receiver,  being  filled  with  water,  and  depressed  into  the  water 
of  the  hydro-pneumatic  cistern,  till  the  apex,  A,  is  on  a  level  with  the  surface,  throw 
up  into  it  the  residual  gas.     In  the  next  place,  draw  it  into  the  eudiometer. 

1000.  In  doing  this  it  is  immaterial  how  much  water  may  follow,  because  the 
quantity  will  be  inferred  from  the  number  of  graduations,  which  must  enter  the  cavity 
of  the  tube,  in  order  to  effect  the  expulsion.     Of  course  the  impurity  will  be  as  the 
number  thus  found. 


NITROGEN.  187 

1001.  A  saturated  solution  of  nitric  oxide  in  the  abovementioned  ferruginous  solu- 
tions, has  the  power  of  absorbing  oxygen,  and  was  recommended  by  Sir  H.  Davy  as 
the  means  of  ascertaining  the  quantity  of  that  gas  in  the  air.  The  mode  of  using 
them  would  be  the  same  as  that  just  described,  taking  oxygen  into  the  eudiometer 
instead  of  nitric  oxide,  and  filling  the  bottle  with  the  ferruginous  solution  of  nitric 
oxide,  instead  of  the  solution  of  the  pure  sulphate  or  protochloride  of  iron.  I  have 
found  this  method  of  ascertaining  the  quantity  of  oxygen  in  the  air,  much  more  te- 
dious and  much  less  satisfactory  than  those  already  described. 

Theory  of  Volumes. 

1002.  It  is  presumed  that  a  reader,  who  has  carefully 
studied  this  work  thus  far,  may  have  his  attention  advan- 
tageously directed  to  the  theory  of  volumes;   otherwise 
the  language,  now  usually  employed  in  treating  of  combi- 
nations resulting  from  the  union  of  gaseous  substances, 
would  not  always  be  intelligible  to  him. 

1003.  It  has  been  advanced  by  Gay-Lussac,  that  sub- 
stances, when  aeriform,  unite  in  volumes  which  are  equal, 
or  that  when  unequal,  the  larger  volume  is  double,  triple, 
or  quadruple  the  other. 

1004.  This  hypothesis  has  been  verified  by  experiment 
with  respect  to  all  substances  which  are  capable,  while 
gaseous,  of  being  combined  or  decomposed.    It  is  extended 
by  inference  to  other  substances,  under  the  idea  that  all 
are  susceptible  of  the  aeriform  state.     A  volume  is  said  to 
be  the  equivalent  of  another  volume,  when  capable  of 
forming  with  it  a  definite  compound,  or  when  just  ade- 
quate to  displace  it  from  combination. 

1005.  It  must  be  evident,  a  priori,  that  if  each  atom,  of 
whatever  kind,  were  to  occupy  in  the  aeriform  state  an 
equal  space,  atoms  might  be  as  well  represented  by  equal 
volumes  as  by  their  equivalent  numbers;   the  former  af- 
fording by  measure,  what  the  latter  give  by  weight.     Now 
experience  justifies  the  belief  that,  in  general,  atoms  do 
assume  an  equality  of  volume  when  rendered  aeriform,  and 
that,  when  the  bulks  assumed  are  unequal,  the  inequality 
may  be  removed  by  multiplying  or  dividing,  by  a  whole 
number,  those  volumes  which  are  smaller  or  larger  than 
the  rest.     This  is  all  that  the  hypothesis  of  Gay-Lussac 
requires. 

1006.  Berzelius  infers  that  water,  and  the  protoxides  of 
chlorine  and  nitrogen,  each  consist  of  one  atom  of  oxygen, 
and  two  atoms  of  the  other  ingredient.     Admitting  this  to 
be  a  correct  inference,  equivalent  weights  of  the  four  ele- 
mentary gaseous  substances  abovementioned,  actually  oc- 


188  INORGANIC  CHEMISTRY. 

cupy  equal  spaces;  so  that  their  atoms  are  as  well  repre- 
sented by  equal  volumes,  as  by  the  numbers  indicating 
their  ratio  to  each  other  in  weight.  But  if  we  suppose 
that,  in  the  compounds  abovementioned,  there  is  only  one 
atom  of  each  ingredient,  the  equivalent  volumes  of  chlo- 
rine, hydrogen,  and  nitrogen,  although  still  equal  to  each 
other  in  bulk,  will  each  be  twice  as  large  as  the  equivalent 
volume  of  oxygen.  The  British  chemists,  in  general,  pre- 
ferring the  last  mentioned  view  of  the  atomic  constitution 
of  the  compounds  abovementioned,  represent  the  atoms  of 
chlorine,  hydrogen,  and  nitrogen,  each  by  one  volume,  the 
atom  of  oxygen  by  half  a  volume. 

1007.  When  gaseous  substances  enter  into  combination 
preserving  the  aeriform  state,  in  some  cases  there  is  a  re- 
duction of  volume,  in  others  none.     When  a  reduction 
does  ensue,  the  bulk,  or  resulting  volume  of  the  compound, 
is  to  the  aggregate  bulk  of  the  constituent  volumes,  either 
as  1  to  2,  1  to  3,  1  to  4,  or  2  to  3,  2  to  5,  &c. 

1008.  This  will  be  rendered  evident  by  the  following 
table,  in  which  the  number  of  atoms  and  the  number  of 
volumes  which   enter   into   some   important   compounds, 
are  represented  by  corresponding  squares.     Each  square 
stands  for  a  volume,  and  half  a  square  for  half  a  volume. 
The  first  column  contains  the  name  of  each  gas  or  va- 
pour; the  second,  the  equivalent  volume  of  the  gas  if  sim- 
ple, or   an  association  of  the  volumes  representing  its 
constituents  if  compound;  the  third,  the  resulting  volume 
of  the  compound  formed;  and  the  last,  the  pressure,  ex- 
pressed in  atmospheres,  necessary  to  produce  liquefaction. 

1009.  Among  the  instances  cited  in  the  table,  it  will  be 
seen  that  there  is  none  in  which  the  bulk  of  the  consti- 
tuent volumes  is  to  that  of  the  resulting  volume  in  a  ratio 
greater  than  that  of  3  to  1.     The  only  permanent  gas,  in 
which  the  elements  are  alleged  to  exist  in   a  state  of 
greater  condensation,  is  olefiant  gas,  consisting  of  two 
volumes  of  the  vapour  of  carbon,  and  two  volumes  of  hy- 
drogen, condensed   into   one  volume.     There  are  some 
vapours,  consisting  of  the  same  elements  in  the  same 
atomic  proportion,  in  which  8  or  9,  or,  according  to  Dr. 
Thomson,  even  25  constituent  volumes  are  contained  in  1 
resulting  volume. 


NITROGEN.  189 

Table  of  the  Equivalent  Weights  and  Volumes  of  some  Gases  and  Vapours. 


Gases  and  Vapours. 


Oxygen    .     . 
Chlorine  .     . 


Protoxide  of  chlo- 
rine . 


Hydrogen     .     .  . 

Steam       .     .     .  . 
Chlorohydric  acid 

Nitrogen  .     .     .  . 

Atmospheric  air  . 

Nitrous  oxide    .  . 

Nitric  oxide       .  . 

Nitrous  acid 


Ammonia 


Component  Volumes. 


08 


Cl 
3(3 


Cl 
36 


08 


C 

36 


08 


N 
14 


N 
14 


08 


O8 


O8 


O 


08 


08 
O8 


H 

1 

H 

1 

N 

H 

14 

1 

lesulting  Volumes  of 
Compounds. 


37 


46 


Pressure  of 
Liquefaction 

Atmospheres. 


4  at  00° 


40  at  50° 


50  at  45° 


at  50° 


190  INORGANIC    CHEMISTRY. 

Of  Nitric  Acid. 

1010.  Although,  under  ordinary  circumstances,  nitrogen 
will  not  combine  with  oxygen;  yet,  when  mixed  with  it, 
and  exposed  to  a  succession  of  electric  sparks,  nitric  acid, 
one  of  the  most  important  agents  in  chemistry,  is  genera- 
ted.    Berzelius  alleges  that  traces  of  nitric  acid,  in  combi- 
nation with  ammonia,  may  almost  always  be  discovered  in 
the  rain  water  accompanying  thunder  storms.    This  chemi- 
cal combination  is  probably  produced  by  lightning.     The 
same  author  states  that  when  a  jet,  consisting  of  one  vo- 
lume of  nitrogen  and  fourteen  of  hydrogen,  is  inflamed 
while  flowing  into  a  vessel  containing  oxygen,  nitric  acid 
is  produced.     There  are  probably  some  unknown  means, 
by  which  chemical  union  is  induced  between  nitrogen  and 
oxygen;    whence  the  great  quantity  of  nitrate  of  potash 
spontaneously  produced, in  various  situations. 

1011.  It  has  been  supposed  that  this  acid   is  formed 
during  the  eudiometrical  analysis  of  atmospheric  air  by 
hydrogen;  and  that  the  deficit  being  thus  increased,  leads 
to  an  undue  estimate  of  the  oxygen.     I  consider  this  im- 
pression erroneous;  as  upon  one  occasion,  by  exploding 
successive  portions  of  hydrogen  with  atmospheric  air,  I 
collected  nearly  half  an  ounce  of  water,  and  found  it  devoid 
of  acidity. 

1012.  Preparation. — The  production  of  nitric  acid  by 
electricity  is  too  laborious  to  be  resorted  to  for  the  purpose 
of  the  chemist. 

1013.  Agreeably  to  the  usual  process,  nitre,  which  con- 
sists of  nitric  acid  and  potash,  is  subjected  to  heat  with  an 
equal  weight  of  sulphuric  acid,  in  a  glass,  porcelain,  or  iron 
retort,  communicating  with  a  glass  receiver.     The  nitric 
acid  is  displaced  by  the  superior  affinity  of  the  sulphuric 
acid   for  the   potash,  and,  being  vaporized  by  the  heat, 
passes  into  the  receiver,  where  it  condenses  into  a  liquid. 
Thus  obtained,  it  is  more  or  less  contaminated  with  nitrous 
acid  or  nitric  oxide,  also  with  chlorohydric,  and  sulphuric 
acid.      By  distilling   from  it  about  a  third  of  the  whole 
quantity,  the  nitrous  and  chlorohydric  acids  pass  over  into 
the  receiver  with  the  portion  of  nitric  acid  distilled,  leaving 
the  residue  in  the  retort  free  from  them.     Sulphuric  acid 
may  be  removed  by  distilling  the  nitric  acid  from  one- 
eighth  of  its  weight  of  pure  nitre,  or  by  the  addition  of  ba- 


NITROGEN.  191 

ryta,  which  precipitates  in  the,  form  of  an  insoluble  corn- 
pound  with  the  sulphuric  acid.  Chlorohydric  acid  may  in 
like  manner  be  removed  by  a  solution  of  silver;  as  this 
metal  forms  with  the  chlorine  an  insoluble  compound  which 
precipitates. 

1014.  Properties. — Nitric  acid  emits  pungent  suffocating 
fumes,  and  has  a  peculiar  odour.     When  pure  it  is  colour- 
less, but  when  exposed  to  the  light,  it  is  slowly  decom- 
posed into  oxygen  gas,  and  nitrous  acid  or  nitric  oxide 
which  is  absorbed,  giving  an  orange  colour  to  the  nitric 
acid.     This  decomposition  takes  place  much  more  rapidly 
in  the  sun.     Nitric  acid  cannot  be  obtained  free  from  wa- 
ter.    With  almost  all  the  metals  it  reacts  powerfully,  also 
with  organic  substances,  causing  them  to  be  oxidized.     It 
stains  and  destroys  the  skin.     It  may  be  considered  as 
consisting  of  the  ingredients  of  atmospheric  air  in  the  liquid 
form,  but  containing  ten  times  as  much  of  the  active  prin- 
ciple, oxygen.     It  is  the  most  energetic  principle  in  gun- 
powder.    In  its  highest  state  of  concentration,  at  a  speci- 
fic gravity  of  1 .55,  one  atom  of  the  acid  contains  one  a  torn 
of  water.    This  concentrated  acid  boils  at  175°  and  freezes 
at — 40°.     When  it  contains  one  atom  of  acid  to  four  of 
water,  it  has  a  specific  gravity  of  1.42,  and  boils  at  248°. 
Any  acid,  whether  weaker  or  stronger  than  this,  has  the 
boiling   point  at  a  lower  temperature.      If  weaker  it  is 
strengthened,  if  stronger  it  is  weakened,  by  boiling;  and 
acids  of  all  degrees  of  strength  become,  by  the  continued 
application  of  a  sufficient  degree  of  heat,  of  the  specific 
gravity  of  1.42.     The  officinal  specific  gravity  is  1.5,  in 
which  case  it  contains  two  atoms  of  water  to  one  of  acid. 

1015.  Nitric  acid  is  employed  in  giving  a  yellow  colour, 
and  for  various  other  puposes  in  manufactures.     It  is  used 
in  medicine  for  fumigations,  in  cases  in  which  chlorine  is 
unsuitable. 

Experimental  Illustrations. 

1016.  The   extrication   and   distillation  of  nitric  acid, 
shown  by  means  of  a  glass  retort  and  receiver,  heated  by 
a  lamp  or  small  sand  bath.     Its  action  on  various  sub- 
stances exemplified. 


192  INORGANIC  CHEMISTRY. 

Of  the  Orange-coloured  Fuming  Nitric  Acid,  called  Nitroso- 
nitric  Acid  in  the  Swedish  Pharmacopoeia. 

1017.  In  whatever  proportion  sulphuric  acid  may  be  em- 
ployed in  the  process  just  described  for  procuring  nitric 
acid,  the  liquid  obtained  is  of  an  orange  colour.     This  co- 
lour becomes  deeper,  when  the  quantity  of  sulphuric  acid 
employed  is  insufficient  to  produce  a  bisulphate  with  the 
potash.     I  am  under  the  impression  that,  in  some  degree, 
the  same  result  follows  when  the  acid  exceeds  the  propor- 
tion requisite  to  produce  the  bisulphate.     In  either  case  the 
water,  which  in  the  absence  of  some  other  base  is  indispen- 
sable to  the  existence  of  nitric  acid,  is  not  furnished  in 
sufficient  quantity.     Hence  the  acid  is  partially  resolved 
into  oxygen  and  nitrous  acid,  which  latter,  together  with 
the  nitric  acid,  passes  into  the  receiver,  constituting  an 
orange-coloured   fuming    liquid,  mentioned  by   Berzelius 
under  the  name  of  nitroso-nitric  acid.     This  acid,  by  expo- 
sure to  heat,  disengages  nitrous  acid  gas,  and  becomes  co- 
lourless nitric  acid.     Nitroso-nitric  acid  ignites  essential 
oils,  carbon,  and  phosphorus;  the  latter  explosively.     It  is 
much  more  energetic  in  its  reaction  with  such  substances 
than  pure  nitric  acid,  which,  probably,  when  nitric  oxide  is 
not  present,  requires  for  its  existence  a  larger  proportion 
of  water.     I  deem  it  probable  that  it  is  with  nitric  oxide, 
not  nitrous  or  hyponitrous  acid,  that  nitric  acid  is  com- 
bined  in   nitroso-nitric   acid.      Berzelius   conceives   that 
either  view  of  its  composition  may  be  correct. 

Experimental  Illustrations. 

1018.  Reaction  of  nitroso-nitric  acid  with  carbon  and 
oil  of  turpentine,  exhibited,  also  with  caoutchouc  tar. 

Of  the  Agency  of  Nitric  Oxide  in  generating  Sulphuric  Acid. 

1019.  When  nitric  oxide,  atmospheric  air,  sulphurous  acid,  and  aqueous 
vapour  are  mingled,  a  crystalline  compound  is  formed,  which,  if  the  ope- 
ration be  performed  within  a  glass  vessel,  will  appear  upon  the  interior  sur- 
face in  a  crystalline  deposition,  resembling  hoar  frost.  When  water  is 
added  to  this  compound,  it  is  resolved  into  sulphuric  acid  and  nitric  oxide. 
The  former  combines  with  the  water,  while  the  latter  escapes  in  the  gaseous 
form,  producing  with  oxygen,  if  present,  the  red  fumes  of  nitrous,  or  hypo- 
nitrous  acid.  It  may  be  inferred  that  hyponitrous  acid,  produced  as  above 
mentioned,  yields  one  atom  of  oxygen  to  the  sulphurous  acid,  converting  it 
into  sulphuric  acid.  The  acid,  thus  produced,  unites  with  the  nitric  oxide 


NITROGEN.  193 

and  water ;  but  on  being  subjected  to  a  larger  portion  of  water,  for  which 
it  has  a  greater  affinity,  the  nitric  oxide  is  allowed  to  escape.  These  habi- 
tudes of  the  agents  in  question  excite  greater  interest,  on  account  of  their 
agency  in  the  generation  of  sulphuric  acid,  one  of  the  most  valuable  of  the 
instruments  which  have  been  placed  within  the  reach  of  the  chemist,  artist 
and  manufacturer. 

Experimental  Illustration  of  the  Reactions  which  occur  in  the 
Manufacture  of  Sulphuric  Acid. 

1020.  Into  a  glass  globe  with  three  tubulures,  insert  through  one  of  them, 
the  beak  of  a  pint  retort,  containing  about  a  pound  of  mercury,  and  as 
much  sulphuric  acid  as  will  cover  it  to  the  depth  of  half  an  inch,  applying 
to  the  retort  a  chauffer  of  coals.     Into  the  other  tubulure,  fasten  the  termi- 
nation of  a  pipe  proceeding  from  a  self-regulating  reservoir  of  nitric  oxide 
gas.    The  third  tubulure  should  be  closed  by  a  glass  stopple.    The  mercury 
takes  one  atom  of  oxygen  from  the  sulphuric  acid,  converting  it  into  sul- 
phurous acid  which  enters  the  globe.  As  soon  as  this  appears  to  have  taken 
place,  a  portion  of  the  nitric  oxide  gas  is  allowed  to  enter  from  the  opposite 
side.     Meeting  with  atmospheric  air  within  the  vessel,  the  nitric  oxide  will 
produce  red  fumes,  which,  encountering  the  sulphurous  acid,  will  condense 
into  a  crystalline  deposition.     Occasionally,  the  stopple  must  be  lifted  to 
allow  the  access  of  fresh  air ;  and  the  supply  of  this  and  the  gases  must 
be  so  regulated,  that  the  red  fumes  shall  be  repeatedly  produced  and  con- 
densed.    When  a  deposition  of  crystalline  matter,  sufficiently  striking,  has 
been  produced,  if  water  be  poured  into  the  globe,  the  deposition  will  be 
speedily  decomposed  with  an  evolution  of  nitric  oxide.     This  gas,  meeting 
with  the  oxygen  of  the  air,  produces  red  fumes,  which,  by  the  readmission 
of  sulphurous  acid,  are  again  condensed  with  it  into  crystals.    These  crys- 
tals, as  before,  by  the  addition  of  water,  are  decomposed  into  nitric  oxide 
gas  and  sulphuric  acid.    The  water  in  the  globe,  being  decanted  and  tested, 
gives  decided  indications  of  the  presence  of  sulphuric  acid. 

1021.  Latterly,  the  process  above  described,  has  been  resorted  to  in 
the  large  way  in  the  manufacture  of  sulphuric  acid.     In  some  cases  the 
nitric  oxide  has  been  evolved  by  the  reaction  of  nitric  acid  with  organic 
substances  of  a  nature  to  produce  oxalic  acid,  but  in  other  manufactories 
the  nitric  oxide  is  obtained  from  nitric  acid  by  subjecting  it  to  sulphuric 
acid,  which  causes  it  to  be  resolved  into  nitrous  or  hyponitrous  acid  fumes 
and  oxygen  gas. 

1022.  When  nitric  oxide  is  obtained  by  the  reaction  of  nitric  acid  with 
sugar  or  molasses,  oxalic  acid  is  produced,  and  tends  to  defray,  partially, 
the  expense  of  the  process. 

Of  the  Process  usually  employed  in  the  Manufacture  of  Sulphuric  Acid. 

1023.  The  combustion  of  one  portion  of  sulphur,  and  the  simultaneous  deflagra- 
tion with  nitre  of  another  portion,  (the  fumes  created  in  both  ways  being  received 
in  a  large  chamber  lined  with  lead,  and  covered  at  bottom  with  water)  are  the  means 
usually  employed  for  the  manufacture  of  sulphuric  acid.     Each  atom  of  nitre  con. 
sists  of  an  atom  of  potash  and  an  atom  of  nitric  acid.     Three  out  of  the  five  atoms 
of  oxygen  in  each  atom  of  the  acid,  unite  with  an  atom  of  sulphur,  converting  it  into 
sulphuric  acid,  which  combines  with  the  potash.     The  two  remaining  atoms  of  oxy- 
gen, together  with  the -nitrogen  of  the  acid,  are  evolved  as  nitric  oxide,  which,  with 
atmospheric  oxygen,  moisture,  and  the  sulphurous  acid  produced  by  the  burning 
sulphur,  generates  the  crystalline  compound  above  described.     Of  late  years,  the 
presence  of  an  adequate  quantity  of  moisture  has  been  insured  by  the  introduction 

25 


194  INORGANIC  CHEMISTRY. 

of  steam  at  proper  intervals.  The  crystalline  compound,  subsiding  into  the  water, 
is  decomposed  into  sulphuric  acid,  which  remains  in  solution,  and  nitric  oxide.  This 
oxide,  meeting  with  further  portions  of  oxygen  and  sulphurous  acid,  again  contri- 
butes to  the  formation  of  the  crystalline  compound,  to  be  again  decomposed.  This 
process  is  continued  until  the  water  in  the  chamber  becomes  sufficiently  impregnated 
with  sulphuric  acid,  when  it  is  transferred  to  leaden  boilers.  In  these  it  is  concen- 
trated by  boiling,  but  it  is  removed  before  it  attains  sufficient  strength  to  attack  the 
lead,  to  a  platinum  alembic,  or  to  glass  retorts,  and  boiled  down  to  the  specific  gra- 
vity of  1.85.  After  it  has  reached  that  density,  no  farther  concentration  can  be  ef- 
fected by  heat.  This,  accordingly,  is  the  standard  specific  gravity  of  the  sulphuric 
acid  of  commerce. 

Production  of  Sulphuric  Add,  further  illustrated. 

1024.  The  apparatus  here  described,  serves  to  show,  in  miniature,  the  process  for 
generating  sulphuric  acid. 


1025.  Provide  a  globular  glass  vessel  with  a  wide  mouth  fitted  to  a  suitable  cover, 
and  capable  of  holding  at  least  eight  gallons,  represented  by  the  preceding  figure. 
Through  a  hole  in  the  centre  of  this  plate,  a  gun  barrel,  open  at  both  extremities,  is 
made  to  descend.     From  the  lower  extremity,  a  ring  of  about  two  inches  in  diame- 
ter is  suspended  by  wires,  hooked  to  a  perforated  circular  piece  of  sheet  metal,  which 
encircles  and  is  soldered  to  the  barrel.     In  the  ring  thus  suspended,  a  conical  frus- 
tum of  iron,  having  an  hemispherical  cavity,  is  seated,  so  as  to  be  a  little  above  the 
water.     Between  the  outside  of  the  gun  barrel,  and  the  inside  of  the  brass  casting, 
C,  which  supports  it.  there  is  a  passage  from  the  pipe,  P,  into  the  cavity  of  the  globe. 
This  pipe  communicates  also  with  the  water  of  a  tumbler,  supported  within  the  bell 
glass.     A  tube  leads  from  a  suction  pump  into  this  vessel,  which  is  placed  on  the 
shelf  of  the  pneumatic  cistern,  covered  with  water  as  usual. 

1026.  The  apparatus  being  thus  arranged,  the  metallic  plate,  with  the  gun  barrel, 
ring,  and  frustum  appended  to  it,  must  be  removed  from  the  globe,  the  iron  frustum 
lifted  out  of  the  ring,  and  some  nitrate  of  potash  (nitre)  being  introduced  into  the 
cavity  in  the  frustum,  it  must  be  made  moderately  red-hot.     It  is  then  to  be  restored 
to  its  seat  in  the  ring,  below  the  gun  barrel,  and  the  plate  and  gun  barrel  must  be 
returned  to  their  previous  position  over  the  mouth  of  the  globe,  so  that  the  whole 
may  be  situated  as  represented  in  the  engraving.     Lumps  of  brimstone,  about  the 
size  of  peas,  are  to  be  dropped  through  the  gun  barrel  into  the  melted  nitre.    As 
each  lump  reaches  the  nitre  a  combustion  ensues,  equally  remarkable  for  beauty  and 
brilliancy.     The  globe  then  becomes  filled  with  sulphurous  acid  gas,  accompanied 
by  nitric  oxide  gas,  and  a  crystalline  deposition  ensues.     Meanwhile,  to  keep  up  a 
supply  of  oxygen  within  the  globe,  and  to  prevent  the  escape  of  fumes  into  the 
apartment,  the  suction  pump  is  put  into  operation,  in  order  to  draw  the  fumes  out  of 
the  globe,  and  cause  them  to  be  replaced  by  air,  which  enters  through  the  gun  bar- 


NITROGEN.  195 

rel.  The  water  rises  from  the  cistern  into  the  bell,  until  the  resistance  which  it 
offers  to  further  elevation,  is  greater  than  that  which  the  water,  in  the  tumbler  on 
the  stand,  opposes  to  the  entrance  of  air  from  the  pipe;  and,  consequently,  the  air  is 
drawn  from  the  globe  through  the  water  in  the  tumbler,  by  which  the  fumes  arising 
from  the  combustion  are  arrested,  especially  if  liquid  ammonia  shall  have  been  pre- 
viously added  to  the  water. 

1027.  To  protect  the  globe  from  the  heat  of  the  red-hot  iron  frustum,  a  cylinder  of 
sheet  lead  is  placed  below  it,  as  represented  in  the  figure. 

1028.  The  fumes  generated  during  this  process,  condense  upon  the  inner  surface 
of  the  globe,  into  a  white  crystalline  compound,  identical  with  that  procured  in  the 
process  above  described.     By  the  affusion  of  water,  this  crystalline  matter  undergoes 
a  decomposition  like  that  already  described,  (1020,)  giving  out  nitric  oxide,  and  yield- 
ing sulphuric  acid  to  the  water. 

COMPOUNDS  OF  NITROGEN  WITH  CHLORINE  AND  IODINE. 

1029.  Neither  chlorine  nor  iodine  combines  directly  with  nitrogen;  but 
both  unite  with  the  nitrogen  of  ammonia,  under  circumstances  which  I 
shall  mention  presently. 

Of  Chloride  of  Nitrogen. 

1030.  This  compound  may  be  obtained  by  placing  a  bell  glass,  filled 
with  chlorine,  over  a  solution  of  one  part  of  nitrate  of  ammonia  in  twelve 
of  water,  at  the  temperature  of  70°.     The  chloride  appears  in  drops,  which 
resemble  olive  oil,  and  which,  being  heavier  than  water,  subside  to  the  bot- 
tom of  the  basin  containing  the  solution.     It  is  remarkable  that  this  sub- 
stance does  not  explode  with  many  combustibles,  which  would  appear  more 
likely  to  decompose  it  than  those  with  which  it  does  explode.     Thus  it  ex- 
plodes with  turpentine  or  caoutchouc,  but  not  with  camphor. 

1031.  The  force  with  which  a  minute  portion  of  chloride  of  nitrogen  ex- 
plodes, on  contact  with  oil  of  turpentine,  would  hardly  be  credited  by  those 
who  have  not  witnessed  this  phenomenon.     An  open  saucer  of  Canton 
china  was  fractured  by  a  globule  not  larger  than  a  grain  of  mustard  seed. 
The  glass  tube  employed  to  project  the  globule  into  the  saucer,  was  violent- 
ly dispersed  in  fragments. 

Of  Iodide  of  Nitrogen. 

1032.  When  iodine  is  kept  in  liquid  ammonia,  it  is  converted  into  a 
brownish-black  substance,  which  is  iodide  of  nitrogen,  and  which  may  be 
collected  and  dried  on  bibulous  paper  at  a  gentle  heat.     The  iodide  of 
nitrogen  thus  formed,  evaporates  spontaneously.     It  explodes  by  a  slight 
pressure,  or  when  heated  or  much  dried,  being  resolved  into  nitrogen  gas 
and  iodine. 


ON  SOME  POINTS  OF  CHEMICAL  THEORY. 

1033.  The  student  has  now  advanced  sufficiently  far  in  practical  know- 
ledge of  the  phenomena  of  combustion,  and  of  the  properties  of  some  acids, 
to  render  it  expedient  to  present  to  him  some  general  views  of  combustion, 
acidity,  and  alkalinity,  arid  additional  instruction  on  classification  and 
nomenclature.  I  am  the  more  inclined  to  this  course,  as,  among  the  com- 
pounds of  nitrogen,  there  are  three  acids  and  an  alkali. 


196  INORGANIC  CHEMISTRY. 

Of  Theories  of  Combustion. 

1034.  Stahl  supposed  the  existence,  in  all  combustibles,  of  a  common 
principle  of  inflammability,  which  he  called  phlogiston,  from  pA«yf£>,  to 
burn.     He  inferred  that  all  substances,  in  burning,  gave  out  phlogiston. 
The  fallacy  of  this  hypothesis  is  evident;  since  metals  become  heavier  du- 
ring combustion,  obviously  in  consequence  of  the  absorption  of  oxygen  from 
the  atmosphere.     By  the  advocates  of  the  phlogistic  theory,  nitrogen  was 
confounded  with  carbonic  acid,  and  carbon  with  hydrogen,  because  both 
carbon  and  hydrogen  were  conceived  to  consist  of  phlogiston  nearly  pure ; 
and  oxygen,  in  combining  with  them,  was  supposed  to  become  phlogisti- 
cated  air,  the  name  then  given  to  nitrogen  gas.     It  is  now  well  known  that 
with  carbon,  oxygen  forms  carbonic  acid,  with  hydrogen  water;  and  that 
nitrogen  gas  contains  neither  carbon  nor  hydrogen. 

1035.  Sulphuric,  and  phosphoric,  acid,  and  metallic  oxides,  were  seve- 
rally supposed  to  be  ingredients  in  the  sulphur,  phosphorus,  and  metals 
producing  them.     Thus  of  two  bodies,  that  which  was  actually  the  lighter 
was  assumed  to  contain  the  other. 

1036.  The  celebrated  Lavoisier,  to  whom  we  are  chiefly  indebted  for  the 
exposure  of  these  fallacies  of  the  theory  of  phlogiston,  having  ascertained 
that  oxygen  is  an  indispensable  agent  in  all  ordinary  cases  of  combustion, 
was  erroneously  led  to  infer  that  it  was  in  all  cases  necessary  to  that  pro- 
cess.    But  it  is  now  well  known  that  there  are  many  instances  of  combus- 
tion, in  which  oxygen  has  no  agency. 

1037.  I  would  define  combustion  to  be  a  state  of  intense  corpuscular  re- 
action, accompanied  by  an  evolution  of  heat  and  light. 

1038.  That  increase  or  diminution  of  temperature  consequent  to  chemi- 
cal combination,  which  constitutes  combustion  when  productive  of  heat  and 
light,  has  been  ascribed  to  a  mysterious  law,  by  which  bodies  undergo  a 
change  in  their  capacity  to  hold  caloric.     It  has  been  supposed  that  the  ca- 
pacity of  the  compound  is  in  some  instances  greater,  in  others  less,  than 
the  mean  capacity  of  the  constituents;  and  that  in  the  former  case  union  is 

'followed  by  an  absorption  of  caloric,  and  of  course  by  cold;  in  the  latter, 
by  the  expulsion  of  caloric,  and,  consequently,  the  production  of  heat. 
Yet,  when  the  capacities  of  compounds  are  compared  with  those  of  their  in- 
gredients, the  result  does  not  justify  the  idea  that  the  heat  given  out  by  the 
latter  in  combining,  is  produced  by  a  diminution  of  capacity.  At  best,  this 
hypothesis  only  substitutes  one  enigma  for  another;  since  it  does  not  ac- 
count for  the  alleged  change  of  capacity. 

1039.  The  diversity  of  power  to  hold  caloric  in  a  latent  state,  technically 
designated  by  the  word  capacity,  is  now  generally  ascribed  to  the  interven- 
ing influence  of  electricity.     It  has  been  shown*  that,  if  neighbouring  bo- 
dies be  electrified  by  means  either  of  glass  or  resin,  previously  subjected  to 
friction,  they  will  repel  each  other ;  but  that  if  one  be  thus  excited  by  glass, 
and  another  by  resin,  attraction  between  them  will  ensue.     Hence  the  ex- 
citements are  considered  of  an  opposite  nature.     It  will  be  recollected  that, 
according  to  the  Franklinian  theory,  the  vitreous  excitement  results  from  a 
redundancy;  the  resinous,  from  a  deficiency  of  the  electrical  fluid.     The 
former  being  designated  as  positive,  the  latter  as  negative  electricity.    Agree- 
ably to  the  doctrine  of  Dufay,  the  different  electric  excitements  are  consi- 
dered as  the  effects  of  two  different  fluids,  attractive  of  each  other,  but  self- 

*  See  my  Treatise  on  Statical  Electricity. 


NITROGEN.  197 

repellent.  The  one  has  accordingly  been  called  resinous,  the  other  vitreous 
electricity.  Yet,  even  by  electricians,  who  suppose  the  existence  of  two 
fluids,  the  terms  positive  and  negative  are  employed. 

1040.  It  has  been  suggested  that  Voltaic  phenomena,  combustion,  acidity, 
alkalinity,  and  chemical  affinity,  may  owe  their  existence  to  the  principle 
by  which  the  different  electric  excitements  are  sustained  in  electrified  bodies, 
modified  in  some  inexplicable  manner,  so  as  to  act  between  atoms  instead 
of  masses.   This  suggestion  derives  strength  from  the  following  facts,  which 
have  been  fully  illustrated  in  my  lectures  on  electricity  and  galvanism. 

1041.  The  pole  of  a  Voltaic  series,  terminated  by  the  more  oxidizable 
metal,  has  been  shown  to  display  a  feeble  electrical  excitement,  of  the  same 
kind  as  that  which  is  producible  by  friction  in  glass ;  while  the  other  pole 
displays  the  opposite  excitement,  in  like  manner  producible  in  resin.    From 
reiterated  experimental  observation  it  is  now  generally  inferred,  that,  of  any 
two  elementary  atoms,  chemically  combined,  and  simultaneously  exposed, 
to  the  voltaic  current,  one  will  go  to  the  positive,  the  other  to  the  negative 
pole.     Atoms  are  supposed  to  have  electrical  states  the  opposite  of  those  of 
the  poles  at  which  they  may  be  liberated,  and  are  said  to  be  electro-negative 
when  liberated  at  the  positive  pole,  or  anode ;  electro-positive  when  liberated 
at  the  negative  pole,  or  cathode.     See  my  Treatise  on  Galvanism,  page  7. 

1042.  Substances  which  have  opposite  relations  to  the  Voltaic  poles,  have 
an  affinity  for  each  other,  which  is  usually  stronger  in  proportion  as  the 
diversity  of  their  electric  habitudes  is  the  more  marked.     Thus,  for  in- 
stance, oxygen,  which  is  pre-eminently  electro-negative,  and  potassium  which 
is  pre-eminently  electro-positive,  have,  under  ordinary  circumstances,  a  pre- 
dominant affinity  for  each  other. 

1043.  On  all  sides  it  must  be  admitted  that  between  chemical  reaction, 
galvanism,  and  electro-magnetism,  there  is  an  intimate  association  which 
must  be  explained  before  the  phenomena  of  chemical  reaction  can  be  well 
understood.* 

1044.  It  has  been  mentioned  that,  of  known  bodies,  oxygen  appears  to  be 
the  most  electro-negative.     It  is  questionable  whether  the  grade  next  to 
oxygen,  in  the  electro-negative  scale,  is  to  be  assigned  to  chlorine  or  fluorine. 
After  these  follow  bromine,  iodine,  sulphur,  selenium,  and  tellurium. 

1045.  Among  the  metals  we  have  a  series  of  substances,  varying  from 
those  in  which  the  electro-positive  power  is  pre-eminently  great,  as  in  potas- 
sium, sodium,  lithium,  barium,  calcium,  magnesium,  &c.,  to  such  metals  as 
belong  rather  to  the  electro-negative  class.     Hence,  setting  out  from  the 
extreme  abovementioned,  we  may  proceed  through  a  long  range  of  metals 
less  and  less  electro-positive,  till  we  arrive  at  such  as  produce  electro- 
negative combinations  with  oxygen  or  chlorine,  or  both.     More  or  less 
within  this  predicament,  I  think  we  find  tin,  mercury,  gold,  platinum,  palla- 
dium, antimony,  arsenic,  molybdenum,  and  lastly  tellurium.     Thus  at  an 
intermediate  point  between  the  extremes  at  which  oxygen  and  the  alkalifi- 
able  metals  are  placed,  there  are  substances  whose  relation  to  the  Voltaic 
poles  is  equivocal  or  wavering;  and  it  should  be  understood  that  this  relation 
is  always  comparative.     Chlorine  is  electro-positive  with  oxygen  and  per- 
haps fluorine,  and  electro-negative  with  every  other  body.  Iodine  is  electro- 
positive with  oxygen,  chlorine,  bromine,  and  probably  fluorine,  while  with 
other  substances  it  is  electro-negative. 

*  See  my  "  Treatise  on  Galvanism,  or  Voltaic  Electricity,  for  Effects  of  Galvanic 
or  Voltaic  Circuits,"  page  19.    And  for  Theory  of  the  same,  page  35. 


198  INORGANIC  CHEMISTRY. 

1046.  Substances  of  the  two  opposite  classes,  in  combining  with  each 
other,  constitute  compounds  which  are  either  electro-positive  or  electro- 
negative, accordingly  as  the  different  energies  of  their  ingredients  prepon- 
derate.    Thus  in  alkalies,  consisting  of  oxygen  united  with  the  alkalifiable 
metals,  the  electro-positive  influence  predominates ;  while  the  reverse  is  true 
of  acids,  consisting  of  the  same  electro-negative  principle,  oxygen,  in  com- 
bination with  sulphur,  nitrogen,  phosphorus,  carbon,  boron,  silicon,  sele- 
nium, or  other  substances,  which,  in  their  electrical  habitudes,  lie  between 
oxygen  and  those  metals. 

1047.  In  some  cases  we  see  an  electro-negative  or  electro-positive  power 
attached  to  compounds,  which  is  not  equally  displayed  by  either  of  their 
constituent  elements  separately.     Cyanogen,  consisting  of  carbon  and  ni- 
trogen, is  a  striking  instance  of  an  electro-negative  compound  thus  consti- 
tuted; and  in  ammonia,  and  the  vegetable  alkalies  lately  discovered,  we 
have  instances  of  electro-positive  compounds,  produced  from  principles  com- 
paratively electro-negative. 

1048.  For  any  further  view  of  the  connexion  between  chemical  and 
galvanic  reaction,  I  refer  to  my  Treatise  on  Galvanism,  or  Voltaic  Electri- 
city, especially  to  pages  7,  17,  35. 

Of  the  Influence  on  Classification  and  Nomenclature  of  the  Habitudes  of 
Chemical  Agents  with  the  Voltaic  Series. 

1049.  It  would  follow  from  the  statements  made  under  the  last  head, 
that  there  should  be  a  resemblance  between  the  properties  of  substances 
which  have  a  proximity  to  each  other  in  the  electric  series.  (1042.)     Ac- 
cordingly we  find,  that  those  which  occupy  the  higher  part  of  the  electro- 
negative scale,  have,  by  distinguished  writers,  especially  in  Great  Britain, 
been  classed  as  supporters ;  while  those  which  are  electro-positive,  or  feebly 
electro-negative,  have  been  by  the  same  authors  classed  as  combustibles. 
Also,  certain  electro-negative  compounds,   formed   of  the  pre-eminently 
electro-negative  principles,  have  been  associated  as  acids;  while  other  com- 
pounds, of  oxygen  at  least,  which  have  the  opposite  polarity,  have  been 
associated  as  bases,  under  some  of  the  subordinate  divisions  of  alkalies, 
alkaline  earths,  earths  proper,  or  simply  oxides. 

1050.  The  idea  of  a  class  of  supporters  of  combustion,  and  of  combustibles, 
has  no  better  foundation  than  that  certain  substances  are  the  most  frequent 
agents  in  combustion.     Thus  hydrogen  will  produce  fire  with  oxygen  and 
chlorine  only ;  sulphur  with  oxygen,  chlorine,  and  the  metals ;  and  car- 
bon with  oxygen ;  but  as  either  oxygen  or  chlorine  will  burn  with  a  greater 
variety  of  substances,  they  have  been  called  supporters  of  combustion,  and 
the  substances  with  which  they  combine  during  combustion,  combustibles. 
Iodine  and  latterly  bromine  have  been  classed  among  the  supporters ;  be- 
cause they  combine  with  almost  all  the  bodies  with  which  the  other  ele- 
ments classed  under  that  name  unite,  and  in  some  cases  with  an  evolution 
of  heat  and  light.     Yet  they  are  not  gaseous  like  oxygen  and  chlorine,  and 
are  as  analogous  to  sulphur  as  to  oxygen.     There  appears  to  me  to  be  an 
error  in  taking  either  of  these  substances  into  the  class  of  supporters,  while 
sulphur  is  excluded,  which,  next  to  oxygen  and  chlorine,  has  the  property 
of  burning  with  the  greatest  number  of  substances.     In  other  respects  sul- 
phur seems,  in  its  properties,  to  be  intermediate  between  iodine  and  phos- 
phorus.    The  habitudes  of  selenium  appear  to  range  between  those  of  tel- 
lurium and  sulphur. 

1051.  Hydrogen,  phosphorus,  carbon,  boron,  and  silicon  are  no  more  en- 


NITROGEN.  199 

titled  to  be  called  combustibles,  than  oxygen,  chlorine,  bromine,  and  iodine, 
&c.  to  be  called  supporters.  It  should  be  observed,  also,  that  these  appella- 
tions are  evidently  commutable  according  to  circumstances;  since  a  jet  of 
oxygen,  fired  in  hydrogen,  is  productive  of  a  flame,  similar  to  the  inflamed  jet 
of  hydrogen  in  oxygen.  If  we  breathed  in  an  atmosphere  of  hydrogen, 
oxygen  would  be  considered  as  inflammable,  and  of  course  a  combustible. 
The  arrangement  which  I  have  adopted  of  classifying  as  basacigen  bodies, 
those  which  have  heretofore  been  treated  as  supporters,  with  the  addition  of 
some  others,  renders  it  unnecessary  to  resort  to  the  incorrect  division  into 
supporters  and  combustibles. 

Method  of  distinguishing  Degrees  of  Oxidizement,  derived  from  the 
School  of  Lavoisier. 

1052.  The  method  which,  in  concurrence  with  Thenard,  I  have  pur- 
sued in  designating  in  the  case  of  the  compounds  formed  by  the  basacigen 
bodies  with  radicals,  the  proportion  of  the  former  ingredient  has  been 
stated.  (756.) 

1053.  In  the  case  of  oxacids  another  method  was  adopted  by  the  Lavoi- 
sierian  school,  which,  with  some  modification,  still  endures,  and  which  I 
shall  state  as  it  now  prevails. 

1054.  Agreeably  to  the  nomenclature  in  question,  where,  in  consequence 
of  different  degrees  of  oxidizement,  substances  form  two  acids,  one  con- 
taining a  larger,  the  other  a  lesser  proportion  of  oxygen,  the  acid,  having 
the  lesser  proportion,  is  distinguished  by  the  name  of  the  substance  oxy- 
genated, and  a  termination  in  ous  ;  that  containing  the  larger  proportion  of 
oxygen  is  designated  in  the  same  way,  substituting  ic  for  ous;  as  sulphur- 
ous  acid  and  sulphuric  acid.     That  ingredient  in  an  acid  or  a  base,  which 
is  least  electro-negative,  is  called  the  radical.     When  an  acid  is  discovered 
having  less  oxygen  than  one  with  the  same  radical,  of  which  the  name 
ends  with  ous,  the  word  hypo  is  prefixed.     Hence  the  appellations,  hypo- 
nitrous,  %posulphurous.     The  same  mean  of  distinction  is  employed  to 
designate  a  degree  of  oxygenation  exceeding  that  designated  by  ous,  but 
less  than  that  designated  by  ic.     Hence  the  name  %posulphuric.     If  there 
be  an  acid  having  still  more  oxygen  than  the  one  of  which  the  name  ends 
in  ic,  the  letters  oxy  are  prefixed. 

1055.  Acids  of  which  the  names  terminate  in  ous,  have  their  salts  dis- 
tinguished by  a  termination  in  ite.     Acids  of  which  the  names  end  in  ic, 
have  their  salts  distinguished  by  a  termination  in  ate.     Thus  we  have 
nitrites  and  nitrates,  sulphites  and  sulphates.     If  the  base  be  in  excess, 
the  word  sub  is  prefixed,  as  sw&sulphate.     If  the  acid  be  in  excess,  super  is 
prefixed,  as  swpersulphate.     The  letters  bi  are  placed  before  the  name  of 
salts  having  a  double  proportion  of  acid ;  hence  carbonate  and  Bicarbonate. 

1056.  The  oxide  in  which  the  oxidizement  is  supposed  to  be  at  the 
maximum  is  called  the  peroxide.     This  monosyllable,  per,  is  also  used  in 
the  case  of  acids,  to  signify  the  highest  state  of  oxygenation,  and  has  been 
(859)  substituted  for  oxy  in  the  case  of  perchloric  acid.    Many  chemists  ap- 
ply the  monosyllable  in  question  to  distinguish  a  salt  formed  with  a  perox- 
ide.    Thus  the  red  sulphate  of  iron  has  been  called  the  persulphate  of  iron. 
The  nitrate  of  the  red  oxide  of  mercury,  the  pernitrate  of  mercury.    Agree- 
ably to  a  similar  rule,  salts  formed  with  protoxides  have  the  word  proto 
prefixed ;  as  in  the  instances  of  proton  itrate,  pro^osulphate,  &c. 

1057.  It  has  already  boon  st.-itod  that  by  the  British  chemists  the  binary- 
compounds  of  oxygen,  chlorine,  bromine,  iodine,  fluorine,  and  cyanogen, 
when  not  acid,  are  designated  by  the  termination  in  ide. 


200  INORGANIC  CHEMISTRY. 

1058.  The  word  oxide  has  been  erroneously  used  as  a  correlative  of  the 
word  acid,  instead  of  being  used  as  a  generic  name  for  any  compound  of 
oxygen,  whether  an  acid  or  base.     I  should  deem  it  preferable  to  apply  the 
termination  in  ide>  to  all  compounds  of  the  basacigen  bodies,  Whether  acids, 
bases  or  neutral,  employing  the  words  acid  and  base  as  terminations  to  in- 
dicate the  subordinate  electro-negative,  and  electro-positive  compounds.    In 
that  case  oxybase,  chloribase,  fluobase,  bromibase,  iodobase,  cyanobase, 
sulphobase,  selenibase,  telluribase,  would  stand  in  opposition  to  oxacid, 
chloracid,  bromacid,  iodacid,  cyanacid,  sulphacid,  selenacid,  telluracid. 
(862,  &c.)    Yet  for  convenience,  the  generic  termination  ide  might  be  used 
without  any  misunderstanding;  and  so  far  the  prevailing  practice  might 
remain  unchanged.     Resort  to  either  appellation  would  not,  agreeably  to 
custom,  be  necessary  in  speaking  of  salts  or  other  compounds  analogous 
to  them ;  since  it  is  deemed  sufficient  Jo  mention  the  radical,  as  if  the  salt 
consisted  of  an  acid  combined  with  a  radical,  not  an  oxide.     Ordinarily  we 
say  sulphate  of  lead,  not  sulphate  of  the  oxide  of  lead.     This  last  mentioned 
expression  is  resorted  to,  only  where  great  precision  is  desirable.     In  such 
cases,  it  might  be  better  to  say  sulphate  of  the  oxybase  of  lead. 

1059.  The  method  of  indicating  the  proportion  of  oxygen  in  an  oxide, 
by  changing  the  termination  from  ous  to  zc,  has  been  generally  adopted 
only  in  the  case  of  the  protoxide,  and  bioxide  of  nitrogen,  the  former  being 
usually  called  nitrous  oxide,  the  latter  nitric  oxide.     In  the  Berzelian  no- 
menclature, this  method  of  discrimination  has  been  extended  to  all  the  com- 
pounds formed  with  amphigen  and  halogen  elements.     Hence  we   have 
chlorure  mercureux,  and  chlorure  mercurique,  for  the  protochloride,  and 
bichloride  of  mercury ;  and  again,  oxide  mercureux  and  oxide  mercurique 
for  the  protoxide  and  bioxide  of  the  same  metal.     These  Berzelian  names 
translated  into  English  would  make   mercurious   chloride  and  mercuric 
chloride,  mercurious  oxide  and  mercuric  oxide. 

1060.  It  should  be  understood  that  the  employment  of  the  terminations 
in  eux  and  ique,  which  in  French  answer  for  ic  and  ous  in  English,  is  ex- 
tended, by  Berzelius,  to  the  case  of  all  oxides  whether  acids  or  bases.    These 
words  are,  in  my  opinion,  neither  agreeable  to  the  ear,  nor  sufficiently  de- 
finite and  descriptive.    In  the  received  nomenclature,  besides  the  case  above 
cited  of  the  bioxide  of  nitrogen,  the  only  other  instance,  of  the  employment 
of  the  letters  ic  to  designate  an  oxide,  is  that  of  the  protoxide  of  carbon, 
called  carbonic  oxide. 

Of  the  Origin  of  the  erroneous  Idea  of  a  Ponderable  Acidifying 

Principle. 

1061.  At  the  period  when  the  French  nomenclature  was  adopted,  oxygen 
was  considered  as  the  sole  acidifying  principle,  whence  its  name  as  already 
stated.  (637.)     Of  course,  every  acid  being  supposed  to  consist  of  oxygen 
in  part,  it  was  enough  to  call  it  an  acid  to  convey  a  correct  idea  of  its  com- 
position in  that  respect.     But  when,  at  a  subsequent  period,  it  was  shown 
that  many  acids  were  destitute  of  oxygen,  and  that  other  substances  were 
nearly  as  efficient  as  oxygen  in  generating  acids  by  a  union  with  acidifiable 
bodies,  it  became  necessary  to  prefix  syllables  in  order  to  distinguish  the 
acid  compounds  produced  by  one  acidifying  principle,  from  those  produced 
by  others.  (856,  &c.)     The  term  acidifying  principle  originated  with  the 
error  of  assigning  that  character  exclusively  to  oxygen.     From  conve- 
nience, more  than  any  conviction  of  its  propriety,  it  was  afterwards  used  oc- 


NITROGEN.  201 

casionally  in  reference  to  chlorine,  hydrogen,  and  other  elements  which 
are  found  to  produce  acids  by  combining  with  a  variety  of  substances.  It 
must  be  obvious  that  there  is  no  adequate  reason  for  considering  any 
ponderable  element  as  an  acidifying  principle. 

1062.  Subsequently  to  the  creation  of  the  word  oxygen,  the  word  radi- 
cal was  employed  to  designate  an  oxidizable  substance.  It  has  since  been 
extended  by  me  to  all  substances  which  form  acids  or  bases  with  the 
basacigen  bodies. 

Of  Acidity, 
j  j 

1063.  Acidity  and  sourness  were  originally  synonymous. 
By  some  of  the  older  chemists,  the  solvent  power  of  cer- 
tain acid  or  sour  liquids,  was  ascribed  to  the  sharpness  of 
their  constituent  particles.     To  this  acuteness  in  form,  the 
power  of  penetrating  and  severing  the  combinations  of 
other  particles  was  attributed.     With  people  in  general, 
the  words  acid,  and  acidity,  still  retain  their  original  signi- 
fication ;  but  by  modern  chemists,  substances  are  associa- 
ted as  acids  which  are  destitute  of  sourness,  and  which 
are  extremely  discordant  in  their  obvious  properties.    Thus 
we  have  in  the  group  of  acids,  sulphuric  acid  and  flint, 
vinegar  and  the  tanning  principle;  also  the  volatile  and 
odoriferous  liquid  called  prussic  acid,  and  the  unctuous, 
insoluble,  inert,  concrete  material  for  candles,  called  mar- 
garic  acid.     It  might  naturally  excite  the  curiosity  of  the 
learner,  to   know  by  what   common   characteristic  sub- 
stances so  discordant  had  been  affiliated.     It  would  be  in- 
ferred that  there  should  be  some  test  of  acidity,  by  which 
to  determine  whether  a  new  compound  should  belong  to 
the  class  of  acids  or  not.     I  am  utterly  ignorant  of  any 
other   common   characteristic,   in   these   otherwise  hete- 
rogeneous substances,   besides   that   common   preference 
for  the  poles,  or  "electrodes"  of  the  Voltaic  series,  on 
which  I  have  founded  my  definition  of  acidity  and  basid- 
ity;   coupled  with   the  inference,   mentioned  in  a  note, 
that  any  compound   capable  of  neutralizing  a  base,   is 
deemed  to  be  an  acid;   and  vice  versa,  any  compound 
capable  of  neutralizing  an  acid,  is  deemed  to  be  a  base. 
(631.)     To  me  it  is  quite  evident  that  it  is  only  upon  one 
or  the  other  of  these  characteristics,  that  many  organic 
compounds  which  are  called  acids,  or  bases,  can  have  any 
pretensions  to  be  designated  as  they  are. 

1064.  Among  the  characteristics  of  acidity  heretofore 
relied  on,  is  that  of  reddening  vegetable  blues.     By  the 

26 


202  INORGANIC  CHEMISTRY. 

soluble  acids,  this  property  is  generally  possessed,  al- 
though an  aqueous  solution  of  sulphurous  acid  is  said  to 
whiten  litmus,  the  vegetable  blue  is  generally  employed  as 
a  test  of  acidity.  But  indigo  is  not  reddened  by  any  acid, 
although  by  nitric  acid  it  is  destroyed.  Solubility,  though 
usually  a  property  of  acids,  is  in  many  cases  wanting,  as 
in  those  of  margaric  and  stearic  acid,  and  others  of  simi- 
lar origin.  The  acid  properties  of  silicic,  and  boric,  acid, 
are  displayed  at  temperatures  incompatible  with  any  other 
solubility,  than  that  which  is  effected  by  the  agency  of 
caloric. 

Of  Alkalinity. 

1065.  Among  the  metallic  oxides  which,  agreeably  to  the 
definitions  above  given,  are  considered  as  bases,  there  are 
a  certain  number  which  are  called  alkalies,  on  account  of 
some  peculiarities  which  I  shall  proceed  to  mention. 

1066.  All  the  alkalies  have  a  peculiar  taste,  called  alka- 
line.    They  all  produce,  in  certain  vegetable  colours,  cha- 
racteristic changes,  which  differ  according  to  the  matter 
subjected  to  them,  but  are  not  varied  by  changing  the  alkali. 

1067.  They  restore  colours  changed  by  acids,  and  are 
capable  of  neutralizing  acidity. 

1068.  Acids  neutralize  alkalies,  and  restore  colours  de- 
stroyed by  them.     Acids  do  not  usually  combine  with 
acids,  nor  alkalies  with  alkalies,  but  acids  arid  alkalies 
unite  energetically  with  each  other. 

1069.  By  the  reaction  of  alkalies  with  oils,  soaps  are 
generated,  which  are  soluble  in  water. 

1070.  Besides  the  alkalies  above  named,  there  are  four 
other  metallic  oxides,  those  of  magnesium,  barium  and 
strontium  for  instance,  which  have  been  called  earths,  and 
which,  in  different  degrees  of  intensity,  have  all  the  alka.- 
line  properties  abovementioned,  excepting  that,  if  not  in- 
soluble, they  have  an  inferior  solubility,  and  that  they  do 
not  form  soluble  soaps. 

1071.  There  are  also  some  vegetable  compounds  which 
possess,  to  a  sufficient  extent,  the  attributes  of  alkalies,  to 
be  classed  among  them. 

1072.  According  to  Bonsdorf,  the  halogen  elements  of 
Berzelius  produce  bases,  which  in  some  cases  display  alka- 
linity.    He  has  noticed  a  change  of  colour,  indicating  an 
alkaline  reaction,  on  litmus  paper,  reddened  previously  by 


NITROGEN.  203 

an  acid,  and  dipped  into  a  solution  of  a  chloride,  either  of 
calcium,  magnesium,  or  zinc. 

1073.  I  infer  that  acidity,  basidity,  alkalinity,  and  gal- 
vanic polarity,  are  due  to  some  inscrutable  influence  of  the 
imponderable  cause,  or  causes,  of  heat,  light,  and  electri- 
city.    To  a  like  influence  I  ascribe  the  sweetness  of  sugar, 
the  pungency  of  mustard  or  pepper,  and  of  essential  oils, 
as  well  as  the  endless  variety  of  odour  with  which  these 
last  mentioned  products  are  endowed.     It  is  evident  that 
in  the  organic  alkalies  and  acids,  alkalinity  and  acidity 
are  found  to  be  associated  with  combinations  of  pondera- 
ble elementary  atoms,  which  exist  in  other  combinations 
without  inducing  alkalinity  or  acidity. 

1074.  It  is  my  intention,  as  introductory  to  the  subject 
of  ammonia,  to  adduce  a  few  experiments  which  illustrate 
the  properties  of  alkalies  in  general. 

Experimental  Illustrations  of  the  characteristic  Effects  of  the 
Alkalies  on  certain  Vegetable  Colours. 

1075.  Into  infusions  of  turmeric,  alkanet,  Brazil  wood, 
and  rhubarb,  a  few  drops  of  solutions  of  either  of  the  alka- 
lies being  introduced, — turmeric,   from  a  bright  yellow, 
becomes  brown;  rhubarb,  from  nearly  the  same  yellow, 
becomes  red.     Brazil  wood,  from  a  light  red,  becomes 
violet-red ;  and  alkanet,  from  red,  becomes  blue.     Acids 
being  added,  the  colours  are  restored,  but  by  a  sufficient 
quantity  of  alkali  are  changed,  as  in  the  first  instance,  and 
by  acids  again  restored ;  so  that  the  experiment  may  be 
repeated  several  times  with  the  same  infusions. 

1076.  A  blue  infusion,  obtained  from  red  cabbage,  is 
rendered  green  by  an  alkali.     By  adding  some  acid,  the 
blue  colour  is  restored;  by  a  further  addition  of  the  acid, 
the  infusion  becomes  red.     An  alkali  being  next  intro- 
duced, it  becomes  blue,  and  by  a  further  addition  of  alkali, 
the  green  colour  reappears.     By  alternately  using  acids 
and  alkalies,  these  changes  may  be  repeated  several  times. 

1077.  The  power  of  various  acids  in  reddening  infusions 
of  litmus,  shown ;  and,  subsequently,  the  restoration  of  the 
blue  colour  by  an  alkali. 


204  INORGANIC  CHEMISTRY. 

COMPOUNDS  OF  NITROGEN  WITH  HYDROGEN. 
Of  Ammonia. 

1078.  As  substances  which  are  analogous  in  their  most 
important  properties,  are  often  utterly  different  in  their 
composition,  it  is  impossible  to  adopt  any  arrangement  in 
treating  of  them,  which  may  be  in  both  respects  satisfac- 

'  tory.  The  compound  which  is  the  subject  of  this  article, 
was  naturally  associated  with  the  other  alkalies,  when 
their  composition  was  unknown;  although  now  generally 
ranged  with  the  compounds  of  nitrogen,  whilst  its  former 
associates  are  placed  among  the  metallic  oxides. 

1079.  This  classification  has  become  the  more  proper, 
as  agreeably  to  the  view  latterly  presented  by  Berzelius, 
it  appears  to  be  doubtful,  whether  ammonia  be  an  alkali. 
But  of  this  I  shall  speak  more  fully,  in  treating  of  ammo- 
nium. (1106,  &c.) 

1080.  Formerly,  besides  ammonia,  only  two  other  alka- 
line substances  were  known,  soda  and  potash,  or  potassa. 
These  being  difficult  to  vaporize,  obtained  the  name  of 
fixed  alkalies,  while  ammonia  being  naturally  aeriform,  was 
called  the  volatile  alkali. 

1081.  A  new  mineral  fixed  alkali   was   discovered  in 
1817,  and  named  lithia.     It  was  procured  from  a  stone 
called  Petalite.     Hence  its  name  from  the  Greek  A,fc/«5, 
stony. 

1082.  Preparation  of  Ammonia. — Ammonia  is  obtained 
from  sal-ammoniac,  the  salt  from  which  it  received  its 
name. 

1083.  To  evolve  this  alkali  in  the  gaseous  state,  equal 
parts  of  sal-ammoniac  and  quicklime,  both  finely  pulve- 
rized, are  to  be  heated  gradually  in  a  glass  matrass.     The 
ammonia  is  partially  extricated  by  the  mere  mixture  of 
the  materials;  but  heat  is  necessary  to  complete  the  ope- 
ration. 

1084.  Sal  ammoniac,  according  to  the  opinion  generally 
entertained,  is  a  compound  of  chlorohydric  or  muriatic  acid 
and  ammonia.     The  lime  having  a  greater  affinity  for  the 
acid  than  the  ammonia,  by  simple  affinity  combines  with 
it,  and  liberates  the  alkali  as  a  gas,  the  state  which  it  na- 
turally assumes  when  isolated.     A  different  view  of  this 
subject  is  taken  by  Berzelius,  which  will  be  explained  when 
treating  of  ammonium.  (1109,  1110.) 


NITROGEN. 


205 


1085.  When  it  is  an  object  to  have  the  gas  perfectly 
free  from  humidity,  it  is  necessary  to  arrest  the  process  as 
soon  as  moisture  begins  to  condense  in  the  neck  of  the  re- 
ceiver; or  to  interpose,  between  the  neck,  and  the  reci- 
pient used  to  receive  the  gas  over  mercury,  a  tube  con- 
taining dry  hydrate  of  potash  in  small  fragments. 

N      Experimental  Illustration  of  the  Process  for  obtaining 
Gaseous  Ammonia. 

1086.  A  flask,  containing  equal  parts  of  quicklime  and 
sal-ammoniac,  both  well  pulverized  and  thoroughly  inter- 
mingled, is  exposed  to  as  much  heat  as  the  glass  will  bear. 

1087.  A  bell  glass  is  so  placed  over  the  mercurial  cis- 
tern, as  to  receive  any  gas  which  may  pass  from  the  ori- 
fice of  a  tube,  luted  at  one  end  into  the  flask  charged  with 
the  materials,  and  at  the  other  entering  the  mercury  so  as 
to  be  under  the  bell.      This  apparatus  is  represented  in 
the  following  cut. 


1088.  Properties  of  Ammonia. — Ammonia  acts  like  an 
alkali  upon  the  organs  of  taste,  upon  vegetable  colours, 
and  in  neutralizing  acidity.  A  very  small  proportion  of 
this  gas,  diffused  in  the  air,  is  intolerable  to  the  eyes  and 
organs  of  respiration;  yet  when  extremely  dilute,  the 
odour  is  agreeably  stimulating.  Its  specific  gravity  is 
0.5897,  and  100  cubic  inches  weigh  18.28  grains.  It  is 
not  inflammable  in  the  air,  yet  inflames  with  chlorine 
spontaneously,  and  with  oxygen,  by  the  aid  of  an  electric 


206  INORGANIC  CHEMISTRY. 

spark,  or  galvanic  ignition.  A  candle  flame  is  at  first  en- 
larged and  afterwards  extinguished  by  immersion  in  this 
gas.  Water  absorbs  it  with  surprising  velocity,  and  will 
hold  from  450  to  670  times  its  bulk.  Ice  melts  in  it  more 
speedily  than  in  a  fire. 

1089.  Heat  either  decomposes,  or  volatilizes,  all  ammo- 
niacal  compounds;  and  either  of  the  fixed  alkalies,  or  of 
the  three  more  powerful  alkaline  earths,  disengage  ammo- 
nia from  any  of  the  acids  with  which  it  may  be  combined. 

1090.  Ammonia,  by  refrigeration  alone,  may  be  con- 
densed into  a  liquid  at  —  40°  F.     By  a  pressure  of  six  at- 
mospheres and  a  half,  Mr.  Faraday  succeeded  in  liquefy- 
ing it  at  the  temperature  of  50°  F. 

1091.  The  decomposition  and  analysis  of  ammonia  have  been  attempted 
by  ignition  with  oxygen  gas.     I  have  often  caused  a  mixture  of  it  with 
oxygen,  to  inflame  by  means  of  a  wire  ignited  by  galvanism.     I  believe  it  to 
be  almost  impracticable  to  ascertain  the  result  accurately  by  measurement, 
on  account  of  the  liability  of  ammonia  to  be  absorbed  by  the  moisture  of 
the  apparatus,  the  water  produced  by  the  combustion,  arid  the  mercury 
employed  to  confine  the  gases. 

1092.  A  spontaneous  and  explosive  combustion  ensues  between  chlorine 
and  the  hydrogen  of  gaseous  ammonia.     When  chlorine  is  passed  in  bub- 
bles through  concentrated  liquid  ammonia,  a  reaction  takes  place  with  so 
much  noise,  as  apparently  to  endanger  the  containing  vessel.    This  process 
has  already  been  mentioned  as  one  of  the  means  of  obtaining  nitrogen. 

1093.  In  its  reaction  with  ammonia  iodine  differs  from  chlorine.     When 
iodine  is  brought  in  contact  with  dry  ammoniacal  gas,  it  forms  a  thick  black 
fluid,  which,  when  saturated  with  ammonia,  becomes  more  liquid.     This 
compound  is  decomposed  by  water  forming  the  iodide  of  nitrogen.  (1032.) 

1094.  With  various   metallic    oxides,  ammonia   forms  explosive  com- 
pounds; especially  those  known  as  fulminating  gold,  and  the  most  dan- 
gerous species  of  fulminating  silver.     By  these  appellations,  however,  other 
compounds  of  those  metals  are  designated.    By  some  inexplicable  influence, 
probably  electro-chemical,  the  affinities  between  the  oxygen  and  hydrogen 
are  suspended  without  being  destroyed.     Yet  by  slight  causes,  whether  me- 
chanical or  chemical,  the  equilibrium  is  subverted  with  explosive  violence. 

Experimental  Illustrations. 

1095.  Sal-ammoniac  and  quicklime,  being  powdered,  and 
mixed  in  small  glasses,  pungent  fumes  are  emitted.  Am- 
monia extricated  by  the  process  above  described,  and  col- 
lected in  bell  glasses  over  mercury.  The  introduction  of 
a  few  drops  of  water  causes  the  gas  to  disappear.  Ice,  in 
the  same  way  introduced  is  liquefied,  and  causes  a  like  re- 
sult. Characteristic  changes  effected  in  the  colour  of  wa- 


NITROGEN.  207 

ter,  tinctured  by  turmeric,  alkanet,  Brazil  wood,  and  rhu- 
barb. 

1096.  Evolution  of  gas  shown  by  means  of  potash  and 
an  ammoniacal  salt,  introduced  into  a  glass  vessel  over 
mercury. 

1097.  Equal   volumes   of   ammonia   and   chlorohydric 
acid,  mixed,  and  condensed  into  a  solid,  constituting  sal- 
ammoniac. 

1098.  Ammonia  inflamed  with  oxygen  gas:  also  with 
chlorine. 

1099.  Synthesis  of  ammonia  by  nitric  oxide  and  hy- 
drogen, heated  with  platina  sponge. 

Of  the  Composition  of  Ammonia. 

1100.  According  to  Berzelius,  ammonia  was  first  ascertained  to  be  a 
compound  of  nitrogen  and  hydrogen,  by  his  celebrated  countryman,  Scheele. 
At  a  later  period,  Berthollet  ascertained  the  ratio  in  which  these  substances 
exist  in  it,  which  is  by  volume  that  of  three  of  hydrogen  to  one  of  nitrogen, 
condensed  into  two  volumes:  and  by  weight,  3  of  hydrogen  to  14  of  nitro- 
gen.    See  Table,  page  189. 

1101.  The  partial  decomposition  of  ammonia  may  be  effected  by  subject- 
ing it  to  a  succession  of  electrical  sparks.     Each  spark  causes  the  decom- 
position of  a  portion  of  the  gas ;  but  as  the  process  proceeds,  it  becomes 
more  difficult,  so  that  a  complete  decomposition  is  impracticable.     That 
portion  which  is  decomposed,  is  doubled  in  volume ;  since  the  three  volumes 
of  hydrogen  and  one  of  nitrogen  occupy,  while  combined,  but  half  of  the 
space  which  they  would  fill  if  uncombined. 

1102.  Ammonia,  by  being  made  to  pass  through  tubes  at  a  red  heat,  is 
resolved  into  its  constituents.     This  result  is  promoted  by  the  presence  of 
metallic  wire.     Any  metal  will  have  more  or  less  effect,  but  iron  is  most 
efficacious.     It  appears  from  recent  experiments  of  Despretz,  that  this  me- 
tal, by  continued  exposure,  may  be  made  to  take  up  nearly  twelve  per  cent, 
of  its.  weight,  becoming  a  nituret  by  the  absorption  of  the  nitrogen  of  the 
ammonia.     It  is  supposed  that  other  metals,  which,  after  a  like  exposure, 
exhibit  no  increase  of  weight,  successively  receive  and  abandon. nitrogen;  an 
operation  which  appears  to  be  singular  and  mysterious.   The  metals  become 
brittle  during  this  process.     Probably  their  influence  is  in  its  nature  electro- 
chemical.    In  its  effects  it  appears  to  be  the  reverse  of  that  by  which  the 
union  of  the  elements  of  water  is  promoted  by  the  presence  of  some  metals 
in  a  state  of  minute  division. 

Process  for  obtaining  Water  from  Ammonia. 

1103.  If  instead  of  being  conveyed  into  a  bell  glass  over 
mercury,  the  gas  be  received  in  water  contained  in  a  phial, 
the  water  may  be  saturated,  constituting  aqua  ammoniac,  or 
water  of  ammonia.  The  saturation  may  be  effected  in  an 
apparatus,  similar  to  that  represented  in  the  following  cut. 


208 


INORGANIC  CHEMISTRY. 


1104.  The  absorption  of  ammoniacal   gas  by  water, 
causes  so  much  heat,  that  it  is  difficult  to  produce  a  saturated 
solution,  without  assisting  the  refrigeration  by  means  of  ice. 

1105.  Water  saturated  with  ammonia,  when  gradually 
cooled  to  the  temperature  of  —  40°  F.,  crystallizes  in  long 
needles  having  a  silky  gloss.     No  doubt  these  crystals 
owe  their  existence  to  the  presence  of  water,  which  exists 
in  them  as  water  of  crystallization.     Water  of  ammonia 
is  lighter  than  water.     In  combining  with  the  gas,  the 
water  loses  weight  in  proportion  to  the  degree  of  impreg- 
nation.    At  the  maximum,  at  ordinary  temperatures,  the 
alkali  constitutes  about  one-third  of  its  weight. 

Of  Ammonium. 

1106.  It  is  well  known  that  Davy  resolved  potash  and  soda  severally 
into  metals  and  oxygen,  by  exposing  those  alkalies  to  the  divellent  influence 
of  the  Voltaic  current.     Subsequently,  Berzeliu's,  not  having  at  command 
an  apparatus  sufficiently  powerful,  when  unassisted,  to  effect  this  decompo- 
sition, ascertained  that,  by  placing  mercury  in  contact  with  a  moistened 
fixed  alkali,  and  in  communication  with  the  negative  pole,  while  the  alkali 
communicated  with  the  positive  pole,  an  amalgam  would  result  either  of 
potassium  or  sodium,  according  to  the  alkali  employed. 

1107.  The  results,  when  ammonia  is  subjected  to  the  galvanic  circuit  in 
contact  with  mercury  at  the  negative  pole,  having  a  perfect  analogy,  as 
respects  the  production  of  an  amalgam,  with  those  obtained  by  a  similar 
exposure  of  the  other  alkalies,  as  above  mentioned,  led  naturally  to  the 


NITROGEN.  209 

inference  that  the  causes  were  analogous;  and  that,  in  the  case  in  question, 
no  less  than  in  the  others,  a  metallic  radical  had  been  deoxidized  and  united 
with  the  mercury.  This  inference  was  rendered  more  plausible  by  the 
evolution  of  oxygen  at  the  positive  pole  during  the  formation  of  the  amal- 
gam. Yet  ammonia  was  known  to  consist  of  hydrogen  and  nitrogen;  and 
to  consider  either  or  both  of  these  as  oxides,  was  inconsistent  with  all  the 
knowledge  otherwise  obtained  respecting  them,  By  some  chemists,  how- 
ever, nitrogen  was  conjectured  to  be  the  oxide  of  a  metal,  with  which  this 
amalgam  was  supposed  to  be  formed.  For  this  supposed  metal,  the  name 
of  nitricum  was  suggested.  Hence  the  contact  of  the  amalgam  with  water 
was  conceived  to  cause  the  absorption  of  oxygen  by  the  nitricum,  and 
consequently  the  extrication  of  hydrogen. 

1108.  Gay-Lussac  and  Thenard  explained  the  formation  of  the  amalgam, 
by  supposing  the  absorption  of  ammonia  by  the  mercury,  together  with  a 
portion  of  hydrogen  derived  from  the  simultaneous  decomposition  of  water. 

1109.  Berzelius  admits  the  fact  of  the  union  of  the  elements  of  ammonia 
and  hydrogen  with  the  mercury,  in  the  proportions  alleged  by  the  distin- 
guished philosophers  above  named;  but  conceives  that,  by  the  addition  of 
an  atom  of  hydrogen  to  the  ammonia,  this  alkali  is  converted  into  a  metal, 
which  he  calls  ammonium.     To  the  union  of  this  metal  with  mercury,  he 
ascribes  the  production  of  the  amalgam;  and  to  a  resolution  of  the  metal 
into  its  elements,  the  evolution  of  the  ammonia  and  hydrogen.     When  an 
atom  of  ammonia  is  presented  to  an  atom  of  water,  he  infers  that  the  hy- 
drogen of  the  water  converts  it  into  ammonium,  which  is  simultaneously 
oxidized  by  the  oxygen.     Hence  an  atom  of  ammonia,  when  combined 
with  an  atom  of  water,  may  be  considered  as  acting  as  an  oxybase  of  am- 
monium.    When  gaseous  ammonia  is  presented  to  chlorine,  one  portion 
of  it  is  decomposed,  of  which  the  nitrogen  is  liberated,  while  the  hydrogen 
converts  another  portion  into  ammonium.     This  forms  with  the  chlorine 
a  chloride  of  ammonium^  and,  accordingly,  by  this  appellation,  sal  ammo- 
niac, or  muriate  of  ammonia,  must  be  designated,  agreeably  to  the  hypo- 
thesis under  consideration. 

1110.  When   in   the   process   already  given   for   obtaining   ammonia, 
chloride  of  ammonium  (sal  ammoniac)  is  mingled  with  the  oxide  of  cal- 
cium (lime,)  by  double  electrive  attraction,  the  chlorine  combines  with  the 
calcium,  and  the  oxygen  with  one  atom  of  the  hydrogen  in  the  ammonium; 
so  that  water  and  ammonia  are  evolved.     The  latter  assumes  the  gaseous 
form,  while  the  water  unites  with  the  chloride,  and  remains  in  union  with 
it,  if  the  heat  be  not  raised  unnecessarily,  and  continued  too  long. 

1111.  If  we  attempt  to  decompose  ammonia  without  the  assistance  of 
mercury,  it  yields  nothing  but  hydrogen  and  nitrogen ;  yet,  to  produce  the 
amalgam,  it  is  sufficient  that  the  wire  employed  be  coated  with  mercury. 
The  globule  of  mercury  which  is  left  after  the  spontaneous  decomposition 
which  the  mass  sustains,  is  in  volume  surprisingly  minute  comparatively 
with  the  amalgam  which  it  contributed  to  form. 

1112.  The  most  convenient  mode  of  obtaining  the  ammoniacal  amal- 
gam, is  to  place  a  globule  of  the  amalgam  of  potassium  in  a  cavity  of  a 
piece  of  chloride  of  ammonium,  slightly  moistened.     The  globule  soon 
enlarges  to  many  times  its  previous  dimensions,  by  the  absorption  of  the 
ammonium,  which  relinquishes  its  chlorine  to  the  potassium. 

1113.  The  ammoniacal  amalgam,  agitated  in  dry  atmospheric  air,  yields 
hydrogen  and  ammoniacal  gas.     The  same  gaseous  substances  are  extri- 
cated from  it  when  plunged  into  ether  or  naphtha.      The  ammoniacal 

27 


210  INORGANIC  CHEMISTRY. 

amalgam  may  be  preserved  for  some  time,  if  surrounded  by  hydrogen,  or 
included  in  a  dry  and  well  closed  bottle.  When  thus  protected,  and  the 
absence  of  water  is  insured  by  the  presence  of  a  small  proportion  of  potas- 
sium, it  may  be  kept  unchanged  for  several  months. 

1114.  Berzelius  does  not  consider  ammonia  as  capable  of  becoming  a 
base,  without  first  being  converted  into  ammonium  by  the  acquisition  of 
hydrogen.     In  this  state,  without  further  change,  it  can,  like  other  metals, 
form  a  salt  by  combining  with  any  of  the  halogen  substances.     But  to  com- 
bine with  oxacids,  the  ammonium  must,  like  other  metals,  be  oxidized. 
The  presence  of  water  at  once  metallizes  and  oxidizes  ammonia.     The 
hydrogen  converts  the  ammonia  into  a  metal,  while  the  oxygen  converts 
that  metal  into  an  oxide. 

1115.  When  gaseous  ammonia  precipitates,  from  an  aqueous  solution  of 
a  haloid  salt,*  a  metal  in  the  state  of  oxide,  water  is  decomposed,  the  hydro- 
gen converting  the  ammonia  into  the  metal  ammonium,  while  the  oxygen 
converts  the  metal  into  an  oxide.     Meanwhile,  the  ammonium,  combining 
with  the  halogen  element  of  the  haloid  salt,  takes  the  place  previously  occu- 
pied by  the  metal  which  has  been  oxidized. 

1116.  Agreeably  to  the  view  taken  above,  water,  by  its  contact  with 
ammonia,  at  once  metallizes  and  oxydizes  it,  since  the  hydrogen  converts 
it  into  ammonium,  while  the  oxygen,  at  the  same  time,  converts  it  into  an 
oxide.    Thus  the  formula  of  ammonia  united  to  water,  would  be  N  H3  X  H° ; 
but  when  it  is  resolved  into  N  H4  X  0,  an  oxide  of  ammonium. 

1117.  It  must  also  follow,  that  it  is  not  by  ammonia  that  the  part  of  an 
alkali  is  performed  when  entering  the  arena  of  alkaline  reaction ;  with  the 
aid  of  water  a  transformation  takes  place,  so  that  the  oxide  of  ammonium 
is  really  the  ammoniacal  alkali.     Of  course  ammonia  cannot,  consistently 
with  this  explanation,  be  considered  as  an  alkaline  gas. 

1118.  I  deem  it  expedient  to  adopt  the  Berzelian  doctrine,  as  it  is  neces- 
sary to  the  symmetry  of  our  classification  both  as  respects  acids,  bases,  and 
chlorides.     To  consider  ammonia,  per  se,  as  forming  salts  with  oxacids,  or 
with  the  halogen  bodies,  would  involve  an  anomalous  deformity,  as  in  all 
other  cases  of  the  union  of  inorganic  acids  and  bases,  the  same  basacigen 
ingredient  exists  both  in  the  acid  and  the  base. 

Experimental  Illustrations. 

1119.  In  a  cavity,  made  in  a  bit  of  muriate  of  ammonia, 
in  communication  with  one  of  the  poles  of  the  Voltaic 
pile,  a  moistened  globule  of  mercury  is  supported.     The 
mercury  is  made  to  communicate  with  the  other  pole.  The 
metal  swells  rapidly,  and  assumes  all  the  characteristics  of 
an  amalgam. 

1120.  An  amalgam  of  potassium,  being  introduced  into 
a  cavity  in  a  piece  of  sal  ammoniac,  is  rapidly  converted 
into  the  ammoniacal  amalgam,  with  a  prodigious  enlarge- 
ment in  bulk. 

*  A  salt  formed  by  a  halogen  element.  (636.) 


PHOSPHORUS.  211 

SECTION  III. 

OF   PHOSPHORUS. 

1121.  Preparation. — Phosphorus   is   obtained  from  the 
phosphate  of  soda  in  urine,  or  the  phosphate  of  lime  in 
bones.  Impure  phosphoric  acid  may  be  extricated  from  the 
earth  of  bones,  by  the  stronger  affinity  of  sulphuric  acid. 
As,  at  a  high  temperature,  charcoal  takes  oxygen  from 
phosphorus,  the  phosphoric  acid  is  decomposed  by  ignition 
with  it  in  a  retort,  the  beak  of  which  is  so  introduced  into 
water,  as  to  have  the  orifice  a  little  below  the  surface. 
Phosphorus  distils  into  the  water,  and  condenses  in  tears. 

1122.  Agreeably  to  another  process,  the  phosphate  of 
soda,  which  may  be  procured  at  the  shops,  is  decomposed 
by  nitrate  of  lead,  by  complex  affinity.     The  phosphorus 
is   separated  from    the    resulting   phosphate  of  lead,  by 
distillation  with  charcoal,  as  in  the  process  above  men- 
tioned. 

1123.  Properties. — Phosphorus  is  often  of  a  light  flesh 
colour,  but  when  pure  is  colourless  and  translucent.     It  is 
rather  harder  than  wax,  but  is  more  easily  divided  by  a 
knife.     Phosphorus  melts  at  108°,  and  inflames  at  148°. 
At  550°  it  boils,  and  may  be  purified  by  distillation  from  a 
retort  filled  with  hydrogen  gas,  receiving  the  product  under 
water.  Phosphorus  is  insipid  and  probably  inodorous;  but, 
in  consequence  of  its  oxidizement,  it  emits  a  feeble  alliaceous 
odour  of  phosphorus,  or  hypophosphoric  acid.    When  pure 
it  is  flexible,  but  the  presence  of  l-600th  of  sulphur  renders 
it  brittle.  Its  specific  gravity  is  1.77.  Subjected  to  the  rays 
of  the  sun,  it  acquires  a  red  colour.     If  heated  to  155°  and 
suddenly  cooled,  it   becomes  black.     Thenard,  however, 
states  that  this  change  cannot  be  effected  in  phosphorus 
which  has  not  been  repeatedly  distilled.     He  suggests  it  as 
possible,  that  the  colour  of  phosphorus,  when  pure,  is  black ; 
and  that  the  colour  which  it  usually  assumes,  may  be  due 
to  the  presence  of  hydrogen,  which  has  been  long  known 
to  be  evolved,  when  phosphorus,  in  the  usual  state,  is  fused 
and  subjected  to  the  Voltaic  current. 

1124.  Exposed  to  the  air  at  ordinary  temperatures,  phos- 
phorus combines  slowly  with  oxygen,  appearing  luminous 
in  the  dark,  but  without  any  sensible  evolution  of  heat. 
Less  heat  is  requisite  to  cause  the  inflammation  of  phos- 


212  INORGANIC  CHEMISTRY. 

phorus  in  atmospheric  air  than  in  oxygen ;  and  less  also 
is  necessary  in  this  last  mentioned  gas,  in  proportion  as 
the  pressure  is  reduced.  When  sprinkled  with  powdered 
sulphur,  carbon,  fluoride  of  calcium,  carbonate  of  lime, 
and  various  other  bodies,  and  placed  in  a  receiver  from 
which  the  air  is  subsequently  exhausted,  phosphorus  in- 
flames. Professor  Alexander  D.  Bache,  who  has  much 
enlarged  the  list  of  substances  capable  of  producing 
this  result,  has  succeeded  in  inflaming  phosphorus  in  an 
exhausted  receiver  by  enveloping  it  in  muslin,  or  in  paper 
pierced  with  small  holes.  He  conceives  that,  with  the  ex- 
ception of  bodies  exercising  a  chemical  affinity,  as  in  the 
instance  of  sulphur,  the  substances  associated  with  the 
phosphorus  act  mechanically,  and  have  upon  it  no  other 
effect  than  that  of  promoting  its  union  with  the  oxygen 
remaining  in  the  receiver.  This  opinion  is  corroborated 
by  the  fact  that  the  removal  of  the  air  may  be  too  rapid,  or 
too  complete,  to  produce  the  inflammation. 

1125.  Phosphorus  may  be  crystallized  from  its  solution 
in  boiling  naphtha,  by  gradual  refrigeration.  Like  sulphur, 
phosphorus,  in  volatilizing,  produces  a  feeble  light,  without 
entering  into  any  chemical  combination.     Water  in  which 
phosphorus  has  been  kept,  oxygen  being  excluded,  acquires 
the  power  of  shining  when  agitated.    The  admission  of  air 
destroys   this   phosphorescent  property.      Phosphorus    is 
oxidized  by  the  action  of  nitric  or  nitrosonitric  acid,  and 
converted  into  phosphoric  acid. 

Experimental  Illustrations  of  the  Properties  of  Phosphorus* 

1126.  Phosphorus  exhibited,  and  inflamed  by  friction  or 
a  gentle  heat.     Luminous  appearance  in  the  dark.     Com- 
bustion in  oxygen,  (654,)  in  nitrous,  and  nitric  oxide,  under 
hot  water  by  a  jet  of  oxygen,  and  by  nitrosonitric  acid. 
(1131.) 

1127.  Anomalous  combustion  of  phosphorus  consequent 
to  rarefaction. 

Combustion  of  Phosphorus  in  Nitric  Oxide. 

1128.  The  backwardness  of  the  gaseous  oxides  of  nitrogen  to  part  with  their  oxy- 
gen to  substances,  under  circumstances  in  which  it  would  be  readily  yielded  by  at- 
mospheric air,  has  been  already  mentioned,  and  a  method  of  illustrating  it  has  been 
described.  (969.)  The  opposite  engraving  represents  an  apparatus,  which  may  be 
used  to  extend  the  illustration  to  nitric  oxide,  which,  producing  a  corrosive  fume  of 
nitrous  acid  by  admixture  with  oxygen,  cannot  be  employed  in  apparatus  requiring 
the  aid  of  an  air-pump,  without  corroding  the  metal  of  which  such  instruments  are 
partially  constituted.  The  apparatus  in  question  is  nearly  the  same  as  that  used  for 


Combustion  of  Phosphorus  in  Nitric  Oxide. 


(Page  212.) 


PHOSPHORUS. 


213 


the  separation  of  nitrogen  from  atmospheric  air.  There  are,  however,  in  this,  two 
additional  tubes;  and  the  bell  employed  is  without  any  cap  or  cock.  The  cock  at 
A,  to  which  a  gum  elastic  bag,  supplied  with  oxygen  gas,  is  attached,  communicates 
with  a  pipe,  which  descends  close  along  the  inner  lateral  surface  of  the  cylindrical 
copper  vessel  till  it  reaches  the  bottom,  then  bends  at  right  angles,  and  proceeds 
along  the  bottom  of  the  vessel  till  it  reaches  the  copper  pipe  in  the  axis  of  the  vessel. 
Next  it  bends  at  right  angles  upwards,  and  ascends  vertically  in  close  contact  with 
the  pipe,  till  it  reaches  the  copper  cup,  g,  by  which  the  pipe  is  surmounted.  It  is 
there  so  recurved  as  to  overhang  and  direct  its  orifice,  t,  downwards,  into  the  cavity 
of  the  copper  cup. 

1129.  Another  tube,  u,  proceeds  from  its  junction  with  a  screw  and  cock,  C,  on 
the  other  side  of  the  vessel,  and  descends  to  the  bottom,  rising  again,  like  the  tube 
abovementioned,  along  the  central  pipe,  till  it  reaches  somewhat  above  the  brim  of 
the  cup,  where  it  terminates  without  a  curvature.     After  the  proper  quantity  of 
phosphorus  has  been  placed  in  the  cup,  the  atmospheric  air  may  be  allowed  to  es- 
cape from  the  bell  glass  through  the  cock,  C,  by  sinking  it  into  the  water,  with 
which  the  vessel  must  have  been  filled  nearly  to  the  brim.     The  air  being  expelled, 
and  a  communication  made  with  a  self-regulating  reservoir  of  nitric  oxide,  by  means 
of  the  flexible  leaden  tube  attached  to  the  cock  for  that  purpose,  the  bell  may  be  sup- 
plied with  a  quantity  of  this  gas,  sufficient  to  occupy  about  two-thirds  of  its  capacity. 
The  cock  being  then  closed,  and  the  communication  with  the  reservoir  interrupted, 
a  red-hot  iron  must  be  introduced  through  the  bore  of  the  central  pipe,  p,  till  it 
touches  the  cup.      For  this  purpose,  it  is  of  course  necessary  that  the  apparatus 
should  be  upon  a  table  with  a  suitable  aperture,  and  of  a  height  sufficient  to  allow 
the  iron  to  enter  the  orifice  of  the  pipe,  p. 

1130.  Although  by  the  heat  of  the  incandescent  iron,  the   phosphorus  will  be 
fused,  no  combustion  will  ensue,  until,  by  opening  a  communication  with  the  gum 
elastic  bag,  a  small  quantity  of  oxygen  is  allowed  to  enter.     But  no  sooner  is  this 
permitted  to  take  place,  than  a  most  brilliant  and  almost  explosive  evolution  of  heat 
and  light  ensues.     A  higher  temperature  is  requisite  to  ignite  phosphorus  in  nitric 
than  in  nitrous  oxide. 

Reaction  of  Phosphorus  toith  Nitroso-nitric  Add. 

1131.  If  into  a  tall  tube  of  about  an  inch  and  a 
half  in  diameter,  and  fifteen  inches  in  height, 
some  strong  nitric  acid  be  introduced,  and  about 
five  grains  of  phosphorus,  a  reaction  will  ensue, 
which  is  invariably  energetic,  and  sometimes  ex- 
plosive.    The  phosphorus  abstracting  oxygen,  the 
acid  is  converted  into  nitric  oxide  gas  and  nitrous 
acid  vapour,  which  are  copiously  evolved,  so  as 
to  fill  the  upper  part  of  the  tube,  and  overflow  it 
with  a  beautiful   red   fume.      Meanwhile,   vivid 
flashes  arise  from  the  oxygenation  of  the  phos- 
phorus, and  pieces  of  it  are  occasionally  thrown 
up  into  the  gas  in  the  tube,  where  a  vivid  com- 
bustion ensues  between  the  phosphorus,  and  the 
oxygen  of  the  nitric  oxide  gas  or  nitrous  acid. 

1132.  The  residual  nitric  acid  will  be  found  in- 
termingled with  phosphoric  acid. 

1133.  Latterly,  in  performing  this  experiment, 
I  have    surrounded   the    tube    with  a  very  stout 
glass   cylinder,  and  another  of  wire  gauze;    as 
upon  one  occasion  a  violent  explosion  took  place, 
which  did  much  damage  to  my  apparatus.     If  the 
phosphorus  be  reduced  into  small  fragments,  the 
risk  of  an  explosion  is  increased.      Heating  the 
acid,  before  the  addition  of  the  phosphorus5,  en- 
sures an  explosive  reaction. 

i 

Application  of  Phosphorus  to  Eudiometry. 

1134.  One  of  the  most  simple  modes  of  ascertaining  the  quantity  of  oxygen  in  the 
air,  is  to  introduce  into  a  graduated  tube,  standing  over  water,  and  containing  100 
measures  of  air,  a  stick  of  phosphorus,  supported  by  a  wire.  The  phosphorus  slowly 
dissolves  in  the  nitrogen,  and,  combining  with  the  oxygen,  condenses  with  it,  and 


214  INORGANIC  CHEMISTRY. 

causes  a  corresponding  absorption  of  the  water.  When,  by  these  means,  the  oxy- 
gen is  all  removed,  the  quantity  of  nitrogen  remaining  will  be  known  by  inspecting 
the  graduation-  The  difference  between  this  quantity  and  100,  the  number  of  mea- 
sures taken,  is  the  quantity  of  oxygen  present. 

A  Simple  Atmospheric  Eudiometer  by  Phosphorus. 

1135.  If  a  cylinder  of  phosphorus  be  supported  upon 
a  wire  (as  represented  in  the  adjoining  cut,)  within  a 
glass  matrass,  inverted  in  a  jar  of  water,  the  oxygen 
of  the  included  air  will  be  gradually  absorbed.      In 
order  to  determine  the  quantity  of  oxygen  in  the  air, 
we  have  only  to  ascertain  the  ratio  of  the  quantity  of 
gas  absorbed,  to  the  whole  quantity  of  air  included  in 
the  matrass  at  the  commencement  of  the  process. 

1136.  This  object  may  be  attained  by  weighing  the 
matrass  when  full  of  water,  and  when  containing  that 
portion  only  which  rises  into  it  in  consequence  of  the 
absorption.     As  the  weight  in  the  first  case  is  to  the 
weight  in  the  last,  deducting  the  weight  of  the  glass 
in  both  cases,  so  will  100  be  to  the  number  of  parts  in 
100  of  atmospheric  air,  which  consist  of  oxygen  gas. 

1137.  Again,  the  contents  of  the  vessel  may  be  dis- 
covered by  the  sliding-rod  gas  measure,  (936,)  and  the 
absorption  measured  by  introducing  from  the  same  in- 
strument, as  much  air  as  will  compensate  it.    As  the 
whole  content  to  the  quantity  which  compensates  the 
absorption,  so  is  100  to  the  quantity  of  oxygen  in  100 
parts  of  the  atmosphere. 

1138.  If  the  neck  of  a  vessel  of  this  kind  hold  about 
one-fourth  as  much  as  the  bulb, — by  graduating  the 
neck,  so  that  each  division  will  represent  a  hundredth 

part  of  the  whole  capacity,  the  result  may  be  known  by  inspection. 

1139.  Eudiometrical  processes  by  the  slow  combustion  of  phosphorus  are  tedious, 
requiring  many  days  to  complete  them,  and  consequently  the  aid  of  barometrical  ob- 
servations to  ascertain  and  allow  for  any  intervening  changes  in  atmospheric  pres- 
sure. 

1140.  It  is  alleged  that  nitrogen  is  enlarged  one-fortieth  of  its  bulk,  by  the  phos- 
phorus which  it  dissolves.     This  is  to  be  deducted  in  estimating  the  residual  gas. 

1141.  The  action  of  the  phosphorus  may  be  accelerated  by  heat;  but  in  that  case 
the  operation  must  be  performed  over  mercury ;  and  the  manipulation  will  be  found 
troublesome  and  precarious. 

1142.  I  have  never  in  this  way,  obtained  results  comparable  in  accuracy  and  uni- 
formity, to  those  procured  by  the  hydro-oxygen  eudiometer.  (940,  &c.) 

Volumescope  for  the  Analysis  of  Atmospheric  Mr  by  Phosphorus. 

1143.  A  volumescope  has  been  described,  (818,)  for  showing  the  diminution  of 
bulk  in  five  volumes  of  atmospheric  air,  consequent  to  the  admixture  of  nitric  oxide. 
The  same  apparatus  may,  with  some  modification,  be  employed  to  show  the  diminu- 
tion of  volume  resulting  from  the  combustion  of  phosphorus.    This  object  is  effected 
by  associating  with  the  volumescope,  the  apparatus  employed  for  the  combustion  of 
phosphorus  in  oxygen.  (654.)     For  this  purpose,  the  volumescope,  instead  of  being 
situated  over  the  pneumatic  cistern,  should  be  placed  in  a  small  tub,  into  the  bottom 
of  which  is  inserted  a  tube,  supporting,  at  the  upper  extremity,  the  cup  for  the  phos- 
phorus.    The  phosphorus  being  placed  in  the  cup,  and  water  in  the  tub,  this  liquid 
is  raised  by  an  air-pump,  until  no  more  than  five  volumes  of  air  remain  in  the  cylin- 
der.    The  phosphorus  is  then  ignited  by  means  of  a  red-hot  iron,  and  the  process 
conducted  as  already  described.  (922.)    As  soon  as  the  expansion  resulting  from  the 
heat  of  the  combustion  ceases,  it  will  be  seen  that  a  little  more  than  one  volume  out 
of  the  five  has  been  condensed. 

COMPOUNDS  OF  PHOSPHORUS  WITH  OXYGEN. 

1144.  These  compounds  are  four  in  number;  one  oxide, 
oxide  of  phosphorus,  and  three  acids,  hypophosplwrous,  phos- 


PHOSPHORUS.  215 

phorous,  and  phosphoric  acid.     Their  composition  is  as 
follows : — 


Three  atoms  of 

phosphorus, 

equivalent  48, 


Two   atoms  of 

phosphorus, 

equivalent  32, 


I  with  one  atom  of  oxygen,  equivalent 
8,  form  oxide  of  phosphorus,  equiva- 
lent 56. 

with  one  atom  of  oxygen,  equivalent  8, 
form  hypophosphorous  acid,  equiva- 
lent 40. 

with  three  atoms  of  oxygen,  equivalent 
24,  form  phosphorous  acid,  equiva- 
lent 56. 

with  five  atoms  of  oxygen,  equivalent 
40,  form  phosphoric  acid,  equivalent 
72. 

Of  Oxide  of  Phosphorus. 

1145.  When  phosphorus,  melted  under  hot  water,  is  subjected  to  a  jet 
of  oxygen  from  a  tube  with  a  capillary  orifice,  oxide  of  phosphorus  and 
phosphoric  acid  are  produced.     The  acid  dissolves,  and  the  oxide,  being 
at  first  suspended  in  the  water,  subsides  subsequently  in  red  flakes.     This 
oxide  is  insipid  and  inodorous.     It  is  not  luminous  in  the  dark,  even  when 
rubbed.     At  a  heat  a  little  below  redness  in  close  vessels,  it  is  decomposed 
into  phosphoric  acid  and  phosphorus.     If  the  air  be  admitted,  phosphoric 
acid  is  the  sole  product.    The  oxide  of  phosphorus  takes  fire  spontaneously 
in  chlorine,  producing  the  perchloride  of  phosphorus  and  phosphoric  acid. 
It  is  inflamed  by  the  action  of  nitric  acid.     With  chlorate  of  potash  it  ex- 
plodes violently;  also  with  nitrate  of  potash  previously  warmed.     The 
white  matter  with  which  phosphorus  becomes  coated  when  kept,  in  water, 
and  which  is  generally  supposed  to  be  a  hydrate  of  the  oxide,  is  stated  by 
Thenard  to  be  a  hydrate  of  phosphorus. 

Production  of  Oxide  of  Phosphorus  experimentally  illustrated. 

1146.  Production  of  oxide  of  phosphorus,  by  the  reaction  of  oxygen  with 
that  substance,  while  in  fusion  under  hot  water. 

Of  Hypophosphorous  Acid. 

1147.  This  acid  is  obtained  by  precipitating  the  baryta  from  an  aqueous 
solution  of  hypophosphate  of  that  base.     The  acid  remaining  in  solution, 
may  be  so  concentrated  by  evaporation  as  to  become  a  vivid  liquid,  highly 
acid,  and  even  crystallizable.     It  is  an  energetic  deoxidizing  agent,  and 
forms  numerous  salts,  all  of  which  are  soluble  in  water,  whereas  several  of 
the  phosphates  are  insoluble. 

Of  Phosphorous  Acid. 

1148.  This  acid  has  been  generally  considered  as  the  product  of  the 
slow  combustion  of  phosphorus  with  atmospheric  oxygen;  but  Thenard 
alleges  that  this  product  is  a  peculiar  acid,  intermediate  in  its  degree  of 


216  INORGANIC    CHEMISTRY. 

oxidation  between  phosphorous  and  phosphoric  acid,  and  to  which  he  has 
given  the  name  of  hypophosphoric  acid.  Phosphorous  acid  may  be  pro- 
cured by  passing  vaporized  phosphorus  over  corrosive  sublimate  heated  in 
a  tube.  Chloride  of  phosphorus  results,  which,  by  reaction  with  water, 
produces  chlorohydric  and  phosphorous  acids.  The  chlorohydric  acid, 
being  more  volatile,  may  be  expelled  by  heat. 

1149.  Phosphorous  acid  is  a  colourless,  inodorous,  crystalline  substance, 
possessing  a  pungent  taste,  and  reddening  litmus  paper.     Like  hypophos- 
phorous  acid,  it  possesses  powerful  deoxidizing  properties. 

Of  Phosphoric  Acid. 

1150.  Preparation. — Phosphoric  acid  may  be  obtained 
by  adding  sulphuric  acid  to  phosphate  of  baryta  suspended 
in  water.     The  sulphuric   acid   unites  with   the   baryta, 
forming  an  insoluble  salt,  which   precipitates  while   the 
phosphoric  acid  remains  in  solution.     When  phosphorus 
is  gradually  added  to -nitric  acid,  phosphoric  acid  is  gene- 
rated, and  remains  mingled  with  the  residual  nitric  acid. 

1151.  Properties. — Phosphoric  acid  is  an  inodorous,  co- 
lourless, viscid  liquid,  possessing  in  a  high  degree  the  pro- 
perty of  reddening  litmus.  It  cannot  be  obtained  in  a  state 
of  liquidity  free  from  water.     When  exposed  to  a  red  heat 
and  afterwards  cooled,  it  forms  a  transparent  brittle  glass. 
This  fusion  should  be  effected  in  a  platinum  crucible ;  since 
phosphoric  acid,  when  heated  to  redness,  attacks  either 
glass  or  porcelain.     The  acid,  if  examined  after  this  ex- 
posure to  heat,  is  found,  although  its  composition  remains 
the  same,  to  have  acquired  new  properties.     On  this  ac- 
count, the  name  of  paraphosphoric  has  been  given  to  it ; 
while  the  term  phosphoric  is  applied  to  designate  the  acid 
in  the  state  first  described.     Nitrate  of  silver  yields  with 
phosphoric  acid  a  yellow  precipitate ;  with  paraphosphoric 
acid  a  white  one.     Albumen  is  coagulated  by  the  latter, 
but  not  by  the  former. 

1152.  Solid  paraphosphoric  acid,  when  exposed  to  the 
air,  deliquesces,  and  is  in  a  few  days  converted  into  phos- 
phoric acid.  The  same  change  is  produced  in  a  short  time 
by  boiling  water.     The  solid  white  flakes  which  are  ob- 
tained during  the  quick  combustion  of  phosphorus  with 
oxygen,  consist  of  paraphosphoric  acid.     It  may  likewise 
be  produced  by  fusing  the  biphosphate  of  soda,  which  by 
these    means   is    converted  into   a   paraphosphate.     Mr. 
Graham,  who  has  made  a  number  of  interesting  experi- 
ments on  this  subject,  states  that  the  acid  which  is  con- 


PHOSPHORUS.  217 

tained  in  fused  phosphate  of  soda,  is  a  third  species  of 
phosphoric  acid,  which  coincides  in  composition  with  the 
others,  but  not  in  properties.  To  this  species  he  has  given 
the  name  of  pyrophosphoric  acid. 

1153.  To  bodies  which  possess  different  properties,  while 
containing  the  same  number  of  atoms  of  the  same  ele- 
ments, and  having  the  same  atomic  weight,  the  term  iso- 
meric  has  been  applied.  Thus,  phosphoric,  paraphosphoric, 
and  pyrophosphoric  acids  are  said  to  be  isomeric  bodies. 

Of  the  Chlorides  of  Phosphorus. 

1154.  It  has  been  shown,  (983,)  that  phosphorus  burns  spontaneously 
in  chlorine.     If  the  chlorine  be  in  excess,  the  perchloride  is  formed;  if  the 
phosphorus  be  in  excess,  the  sesquichloride  is  obtained.     The  sesquichlo- 
ride  is  a  transparent,  colourless,  fuming,  inflammable  liquid,  heavier  than 
water,  and  having  a  disagreeable  smell.     When  brought  into  contact  with 
water,  a  reciprocal  decomposition  takes  place,  and  chlorohydric  and  phos- 
phorous acid  are  produced.     The  perchloride  is  a  white,  crystalline,  in- 
flammable body,  which  is  converted  into  vapour  at  a  temperature  much 
below  212°.     It  forms  a  neutral  compound  with  ammonia,  and  its  vapour 
is  alleged  to  redden  dry  litmus  paper.     Hence,  by  some  chemists,  it  is 
considered  as  an  acid.     I  doubt  whether  litmus  paper  is  ever  reddened  by 
an  acid,  unaided   by  water.     The  perchloride  and  water  decompose  each 
other,  forming  phosphoric  and  chlorohydric  acid.     The  chlorine  bears  the 
same  ratio  to  the  phosphorus  in  these  chlorides,  as  the  oxygen  bears  to  the 
phosphorus  in  phosphorous,  and  phosphoric  acid. 

Of  the  Bromides  and  Iodides  of  Phosphorus. 

1155.  The  sesquibromide  is  a  yellow  fuming  liquid;  the  perbromidc,  a 
crystalline  volatile  solid.     In  their  reaction  with  water  and  composition, 
they  agree  with  the  chlorides  of  phosphorus.     Iodine  appears  to  combine 
with  phosphorus  in  almost  every  proportion.     There  are,  however,  at  least 
two  definite  comoinations,  which  correspond  in  composition  with  the  chlo- 
rides and  bromides. 

Of  the  Sulphides  and  Selenides  of  Phosphorus,  commonly  called  Sulphu- 
rets  and  Seleniurets. 

1156.  When  phosphorus  is  melted  with  sulphur,  or  when  sprinkled  with 
it,  and  placed  in  a  receiver  from  which  the  air  is  subsequently  withdrawn, 
(1124,)  a  sulphide  of  phosphorus  is  formed.     This  sulphide  may  consist  of 
various  proportions  of  its  ingredients,  according  to  the  circumstances  under 
which  it  is  produced.     Sometimes  it  is  liquid,  sometimes  solid. 

1157.  Selenium,  like  sulphur,  combines  with  phosphorus  in  almost  every 
proportion.     The  sulphides  and  selenides  of  phosphorus  are  decomposed 
by  water. 

1158.  The  incorporation  of  sulphur  with  phosphorus,  when  effected  by 
heat,  is  sometimes  productive  of  explosion;  and  the  resulting  mass  is  spon- 
taneously inflammable  in  the  air;  being  the  sole  active  ingredient  in  some 
friction  matches. 

28 


218 


INORGANIC    CHEMISTRY. 


COMPOUNDS  OF  PHOSPHORUS  WITH  HYDROGEN. 
Of  Protophosphuretted  Hydrogen. 

1159.  Protophosphuretted  hydrogen  may  be  obtained  by  heating  a  con- 
centrated solution  of  phosphorous  acid,  or  by  adding  phosphorus  to  the  ma- 
terials for  generating  hydrogen. 

1160.  Properties. — It  is  a  colourless,  inflammable  gas,  with  an  odour 
similar  to  that  produced  by  the  combustion  of  arsenic.    Under  the  ordinary 
pressure  of  the  atmosphere,  protophosphuretted  hydrogen  does  not  inflame 
spontaneously  with  oxygen ;  but,  if  the  pressure  be  reduced  about  one-third, 
combustion  ensues. 

1161.  On  meeting  with  oxygen,  this  gas  becomes  luminous  in  the  dark, 
in  consequence  of  the  slow  combustion  of  the  phosphorus ;  though  the  heat 
evolved  is  inadequate  to  inflame  the  hydrogen.     If  the  process  for  pro- 
ducing the  philosophical  candle,  (806,)  be  repeated  with  the  addition  of 
some  comminuted  phosphorus  to  the  materials,  protophosphuretted  hydrogen 
will  be  generated,  and,  escaping  into  the  air,  will  produce  a  jet  luminous  in 
the  dark. 

Of  Perphosphuretted  Hydrogen. 

1162.  Perphosphuretted  hydrogen  may  be  produced  by  the  reaction  of 
chlorohydric  acid  with  the  phosphuret  of  calcium,  which  is  obtained  by  sub- 
jecting lime  to  the  vapour  of  phosphorus  at  a  bright  red  heat  in  a  porcelain 
or  coated  glass  tube.     The  gas  may  also  be  evolved  by  heating  in  a  retort, 
75  grains  of  phosphorus,  1500  of  slacked  lime,  with  4  ounces  of  water;  or 
50  grains  of  caustic  potash,  and  40  of  phosphorus,  moistened  by  60  drops 
of  water.     The  phosphorus  should  be  added  first,  and  the  potash  last ;  as 
the  heat  which  it  evolves,  contributes  to  the  heat  required  for  the  operation. 
The  body  of  the  retort  should  be  filled  with  hydrogen,  or  a  few  drops  of 
ether  should  be  added,  to  prevent  the  first  portions  of  the  gas  from  inflaming 
with  the  atmospheric  oxygen  of  the  retort.     By  its  affinity  for  the  phospho- 
rus, and  the  metal  of  the  phosphuret,  the  oxygen  of  the  water  is  separated 
from  the  hydrogen,  which,  while  nascent,  unites  with  a  portion  of  the  phos- 
phorus, and  forms  perphosphuretted  hydrogen. 

1163.  The  following  cut  represents  the  apparatus  usually  employed  for 
obtaining  perphosphuretted  hydrogen. 


1164.  The  beak  of  the  retort  being  depressed  below  the  surface  of  the 


PHOSPHORUS.  219 

mercury,  each  bubble  as  it  escapes  into  the  atmosphere,  explodes.  It  pro- 
duces at  the  same  time  a  dazzling  flash,  which  is  transformed  into  a  beau- 
tiful wreath  of  smoke,  consisting  of  aqueous  vapour  and  phosphoric  acid, 
created  by  the  oxygenation  of  the  hydrogen  and  phosphorus.  Each 
wreath,  as  it  rises,  expands  in  diameter,  and,  when  the  bubbles  succeed  each 
other  quickly,  a  series  of  them  may  be  seen  in  the  air  at  the  same  time. 

1165.  Properties. — Perphosphu retted  hydrogen  is  a  colourless  gas,  pos- 
sessing an  alliaceous  smell,  and  a  bitter  taste.     Water  dissolves  it  in  small 
quantity,  forming  a  yellow  solution,  which  has  a  bitter  taste,  and  a  smell 
resembling  that  of  the  gas.     When  this  gas  is  brought  in  contact  with  oxy- 
gen, or  atmospheric  air,  it  explodes  with  a  loud  noise  and  a  vivid  flash ; 
being  converted  into  phosphoric  acid  and  water.     The  same  mixture,  in 
narrow  tubes,  undergoes  a  similar  change  slowly,  and  without  the  evolution 
of  heat  and  light. 

1166.  Perphosphuretted  hydrogen  may  be  decomposed  either  by  heat, 
by  the  electric  spark,  or  by  the  rays  of  the  sun.     Professor  Rose  considers 
protophosphuretted    and   perphosphuretted  hydrogen  as  isomeric,  and   of 
course  similar  in  composition,  though  different  in  properties.     If  the  opi- 
nions of  Rose  are  correct,  one  should  be  called  phosphuretted  hydrogen,  the 
other  paraphosphuretted  hydrogen.  (1153.) 

1167.  Chemists  do  not -agree  in  their  statements  respecting  the  composi- 
tion of  the  compounds  of  hydrogen  with  phosphorus. 

Method  of  exhibiting  the,  Inflammation  of  Small  Portions  of  Gas. 


1168.  This  figure  illustrates  an  advantageous  employment  of  the  sliding-rod  eudi- 
ometer, in  exhibiting  the  spontaneous  combustion  of  phosphuretted  hydrogen,  the 
splendid  colour  of  the  flame  of  cyanogen,  and  other  experiments,  where  the  combus- 
tible character  of  a  small  quantity  of  gas  is  to  be  shown. 

1169.  For  the  experiments  in  question,  the  instrument  is  charged,  agreeably  to  the 
mode  already  described  in  the  case  of  the  eudiometers,  by  introducing  the  apex  into 
any  bell  glass  or  other  vessel  holding  the  gas,  and  drawing  out  the  rod;  by  which  a 
portion  of  the  gas,  equivalent  in  bulk  to  the  part  of  the  rod  withdrawn,  enters  the 
receiver  of  the  eudiometer  through  the  hole  in  the  apex.     The  receiver  being  then 
removed  from  the  bell  glass,  and  held  up  in  a  position  favourable  for  observation,  the 
rod  is  slowly  returned  into  its  tube,  so  as  to  expel  the  gas  in  a  jet  suitable  for  inflam- 
mation.    In  the  case  of  perphosphuretted  hydrogen,  the  gas  burns  spontaneously  as 
soon  as  it  escapes  from  the  apex.     In  the  case  of  other  inflammable  gases,  inflamma- 
tion is  produced  by  the  flame  of  a  taper. 


220  INORGANIC  CHEMISTRY. 

SECTION  IV. 

OF  CARBON. 

1170.  Nature  presents  us  with  the  most  beautiful  and 
purest  specimens  of  this  substance.     The  diamond  is  pure 
carbon.     When  equal  weights  of  charcoal  and  diamond 
are  severally  exposed  to  the  focus  of  a  powerful  lens  in 
oxygen  gas,  included  in  different  bell  glasses,  they  are 
both  converted  into  carbonic  acid,  from  which,  by  ignition 
with  potassium,  carbon  may  be  precipitated. 

1171.  Carbon  is  very  abundant  in  nature,  in  the  various 
kinds  of  fossil  coal,  from  anthracite  or  plumbago,  in  which 
it  is  nearly  pure,  to  the  variety  called  candle,  or  cannel 
coal,  which  abounds  with  bitumen.     In  bituminous  coal 
there  is  much  hydrogen.     Carbon  pervades  vegetable  and 
animal  matter  as  an  essential  element.    It  is,  especially,  a 
constituent  of  the  fibres  of  wood. 

'1172.  Until  of  late,  plumbago  was  considered  as  a  che- 
mical compound  of  iron  with  carbon.  Berzelius  alleges  it 
to  be  carbon  mingled,  but  not  combined,  with  iron  and 
other  impurities. 

1173.  I  ascertained  that  anthracite,  when  completely 
burned  in  oxygen  gas,  produced  no  diminution  of  volume, 
the   products    being  water  and   carbonic  acid.     I  infer, 
therefore,  that  the  combustible  portion  of  this  coal  con- 
sists almost  solely  of  carbon,  united  with  hydrogen  and 
oxygen  in  the  proportion  for  forming  water.     It  may,  in 
fact,  be  deemed  an  hydrate  of  carbon. 

1174.  Preparation. —  In  the  laboratory,  charcoal  is  ob- 
tained,  sufficiently  pure,   by  heating  wood   intensely  in 
close  vessels.     In  the  large  way,  it  is  procured  by  igniting 
large  quantities  of  wood,  so  covered  with  earth,  that  the 
access  of  air  may  be  at  first  controlled  and  afterwards 
prevented. 

1175.  Coke  is  obtained  from  bituminous  coal,  by  a  pro- 
cess analogous  to  that  employed  for  obtaining  vegetable 
charcoal,  which  it  resembles  in  chemical,  though  not  in 
mechanical  properties. 

1176.  Properties. — Carbon   is    inodorous,   insipid,   and 
usually  black.     Charcoal  of  wood  is  one  of  the  best  radia- 
tors, and  worst  conductors  of  heat.     There  is  reason  for 
believing  this  peculiarity  to  result  from  its  excessive  poro- 


CARBON.  221 

sity;  as  in  the  form  of  anthracite,  carbon  conducts  heat 
better,  and  probably  radiates  it  worse.  Charcoal  is  highly 
susceptible  of  galvanic  ignition. 

1177.  Next  to  the  metals,  charcoal  is  the  best  conductor 
of  electricity.     It  appears,  from  the  experiments  of  Pro- 
fessor Silliman,  that  charcoal,  when  exposed  to  the  influ- 
ence of  a  powerful  Voltaic  series,  is  volatilized,  so  as  to 
be  transferred  from  the  positive  to  the  negative  pole,  on 
which  it  forms  a  projection. 

1178.  Charcoal,  when  intensely  ignited  without  access 
of  air,  becomes  denser,  harder,  and  a  better  conductor  of 
heat.     Substituting  animal  products  for  those  of  vegeta- 
tion, in  the  usual  process  of  carbonization,  animal  char- 
coal is  obtained.     It  does  not,  like  the  coal  of  vegetable 
substances,  retain  the  form  of  the  bodies  from  which  it 
may  be  procured,  and  is  replete  with  cavities,  created  by 
the  escape  of  the  gaseous  elements  associated  with  it  in 
the  organic  state.     It  has  a  grayish-black  colour,  and  a 
brilliancy  resembling  that  of  plumbago.     Carbon  is  preci- 
pitated in  various  forms  from  coal  gas;  among  others,  in 
that  of  long  brittle  filaments,  associated  in  tufts,  resem- 
bling locks  of  hair. 

1179.  The  specific  gravity  of  carbon,  in  the  state  of 
diamond,  or  in  that  of  common  charcoal,  when  examined 
in  the  pulverulent  form,  so  that  the  result  shall  not  be 
affected  by  the  numerous  cavities  existing  in  it  when  in 
mass,  is  about  3.5.     The  apparent  lightness  of  charcoal 
is  caused  by  its  porosity.     The  specific  gravity  of  anthra- 
cite does  not  exceed  1.6;  that  of  plumbago  is  2.32;  yet 
they  are  both  much  more  compact  than  charcoal,  and,  in 
proportion  to  the  space  occupied  by  them  in  mass,  ob- 
viously much  heavier. 

1180.  Carbon,  under  some  circumstances,  appears  to 
have  a  transcendent  affinity  for  oxygen.     In  its  ordinary 
state  it  requires  a  temperature  above  redness,  in  order  to 
exhibit  this  affinity — in  other  words,  to  burn.     In  propor- 
tion as  it  becomes  denser,  we  find  it  more  difficult  to 
ignite;  in  proportion  as  it  may  be  more  minutely  divided, 
or  approaches  a  state  of  extreme  porosity,  it  is  rendered 
more  susceptible  of  ignition.     Thus  the  susceptibility  of 
ignition  increases  from  the  diamond  to  tinder  in  the  fol- 
lowing order: — Diamond,  plumbago,  anthracite,  coke,  char- 
coal of  hard  wood,  charcoal  of  soft  wood,  tinder.    In  some 


222  INORGANIC  CHEMISTRY. 

forms,  and  when  mixed  with  iron,  as  when  obtained  by 
carbonizing  Prussian  blue,  or  tanno  gullate  of  iron,  it  takes 
fire  spontaneously  at  ordinary  temperatures. 

1181.  According  to  Despretz,  carbon,  during  its  com- 
bustion, evolves  sufficient  caloric  to  melt  one  hundred  and 
five  times  its  weight  of  ice.     It  is  not  to  be  inferred  that 
this  is  true  of  carbon  in  all  its  forms.     Berzelius  alleges 
that  the  same  degree  of  heating  power  is  not  possessed  by 
every  kind  of  charcoal;  some  of  its  forms,  according  to 
him,  producing  much  more  heat  in  burning  than  others. 
This  I  should  not  believe  without  conclusive  evidence. 

Of  the  Decolorizing  and  Disinfecting  Power  of  Charcoal. 

1182.  Carbon,  as  procured  from  organic  products,  espe- 
cially animal  matter,  displays  a  great  power  to  combine 
with  and  precipitate  colouring  matters.     Hence  it  is  ex- 
tensively used  in  the  refining  of  sugar,  and  generally  in 
chemical  processes,  in  which  the  objects  of  research  are 
entangled  with  colouring  matter.     This  power  is  not  inhe- 
rent in  elementary  carbon,  but  appears  to  be  due  to  its 
previous  associations,  or  to  some  peculiarity  of  arrange- 
ment, derived  from  the  process  of  carbonization. 

1183.  Animal  charcoal  is-  much  more  efficacious  than 
that  derived  from  vegetables.     The  carbonaceous  mass, 
obtained  by  igniting  blood  with  carbonate  of  potash,  ap- 
pears to  have  the  greatest  efficacy.     That  the  presence  of 
an  alkali  during  the  ignition  contributes  to  the  effect,  seems 
to  justify  the  conjecture  that  cyanogen,  the  generation  of 
which,  in  combination  with  the  alkali,  is  a  necessary  con- 
comitant, has  some  agency  in  the  process.     Charcoal  is 
a  powerful  antiseptic,  operating  efficiently  in  preserving 
water  or  meat  from  putridity.     Moreover,  water  rendered 
extremely  foul,  as  that  from  the  public  sewers,  may  be  pu- 
rified by  filtration  through  pulverized  charcoal.     In  fact, 
filters  are  now  extensively  manufactured,  in  which  charcoal 
is  the  most  efficient  and  only  chemical  agent  employed. 
The  gravel,  sand,  and  sponge,  usually  associated  with  it, 
act  mechanically. 

Of  the  Power  of  Charcoal  and  other  Substances  to  absorb  Aeriform 

Fluids. 

1184.  Charcoal,  which  has,  in  a  state  of  ignition,  been  submerged  in 
mercury,  on  being  introduced  into  gaseous  substances,  condenses  into  its 


CARBON. 


pores  a  large  quantity  of  the  surrounding  aeriform  matter,  whatever  it  may 
be.  The  quantity  condensed  varies  with  the  gas,  from  90  times  the  bulk 
of  the  charcoal,  as  in  the  case  of  ammonia,  to  1.75  times  its  bulk,  as  in  the 
case  of  hydrogen.  During  their  absorption,  the  gases  give  out  heat,  and 
the  more  in  proportion  to  the  rapidity  with  which  the  condensation  is  effect- 
ed; and  if,  on  the  other  hand,  by  exposure  within  an  exhausted  receiver, 
the  gas  be  evolved,  cold  is  produced.  Charcoal,  thus  deprived  of  gas,  re- 
absorbs  any  gas  exposed  to  it,  as  greedily  as  if  recently  ignited. 

1185.  This  faculty  of  absorbing  gaseous  substances,  is  impaired  by  hu- 
midity}  which  charcoal  is  prone  to  absorb  in  the  form  of  vapour,  afterwards 
condensing  it  into  the  state  of  water.     Water  partially  displaces  the  gases 
previously  absorbed. 

1186.  The  aeriform  fluids,  absorbed  by  charcoal,  arc  expelled  by  heat 
unchanged,  with  the  exception  of  sulphuretted  hydrogen  and  oxygen.    The 
former  deposites  sulphur,  and  the  latter  is  gradually  converted  into  carbonic 
acid.     The  absorption  of  this  last  mentioned  principle  continues  for  some 
time,  but,  in  quantity,  has  not  been  found  to  exceed  14  times  the  volume  of 
the  carbon.     In  a  rarefied  medium,  charcoal  absorbs  less  in  weight,  but 
more  in  volume;  so  that  the  increased  resistance  of  the  gas,  arising  from  a 
diminution  of  pressure,  counteracts,  to  a  certain  extent,  the  power  of  the 
coal  to  condense  into  its  pores  a  certain  weight.     The  power  of  absorption 
varies  in  a  degree  with  the  number  and  minuteness  of  the  pores  existing  in 
the  charcoal  ;  of  course,  it  varies  with  the  wood  by  which  it  is  yielded. 
Charcoal  of  box-wood  is  pre-eminent  in  absorbing  power;  that  furnished 
by  woods  of  a  lighter  kind  is  very  inferior  in  this  power.     Plumbago  and 
anthracite  have  no  capacity,  even  after  ignition,  to  absorb  gases. 

1187.  In  the  property  of  absorbing  aeriform  fluids,  charcoal  is  not  sin- 
gular.    De  Saussu  re'  ascertained  that  different  porous  minerals,  and  many 
kinds  of  wood,  also  silken  and  woollen  stuffs,  absorb  many  times  their  vo- 
lume of  gas. 

1188.  When  porous  bodies  are  placed  in  a  mixed  atmosphere  of  various 
gases,  they  are  absorbed  in  proportion  to  their  reciprocal  attractions,  and 
that  exercised  by  the  pores  of  the  substances  employed.     A  mixture  of 
oxygen  with  hydrogen  or  carbonic  acid,  is  more  copiously  absorbed  than 
either  when  alone;  yet  by  heat  or  exhaustion  they  are  liberated  without 
diminution.     Nevertheless,  sulphuretted  hydrogen  and  oxygen,  when  acted 
upon  by  charcoal,  produce  water,  sulphur  being  deposited. 

1189.  The  absorption  of  moisture  by  charcoal  and  other  porous  bodies 
has  long  been  noticed.     On  this  account,  it  is  difficult  to  weigh  such  bodies 
without  an  increase  of  their  weight,  even  when  they  are  placed  in  the  scale 
while  red-hot.     Those  aeriform  fluids  are  absorbed  to  the  greatest  extent, 
which  are  capable  of  assuming  the  liquid  state.     These  facts  explain  the 
augmentation  in  weight  received  by  charcoal  exposed  to  the  air,  which 
amounts  to  between  ten  and  twenty  per  cent. 

1190.  I  have  devoted  more  space  to  this  subject,  because  it  illustrates  a 
property  which  otherwise  might  not  be  sufficiently  considered.     It  forms  a 
peculiar  instance  of  mechanico-chemical  agency,  if  I  may  be  allowed  to 
use  a  new  word  to  express  the  idea.     Without  the  porous  or  cellular  struc- 
ture which  it  possesses  in  the  form  of  charcoal,  carbon  is  not  endowed 
with  either  disinfecting,  absorbing,  or  colour-removing  powers;   and  yet 
it  is  evident  that  the  carbon  acts  in  charcoal  by  a  species  of  chemical  af- 
finity, unaided  by  which  the  cellular  structure  would  be  inefficient  in  the 
processes  under  consideration.     As  respects  the  transmission  of  contagious 


224  INORGANIC  CHEMISTRY. 

or  infectious  effluvia,  the  absorbing  power  of  porous  bodies  merits  attention. 
I  believe  that  the  carbonaceous  matter,  evolved  during  the  burning  of  sugar, 
actually  neutralizes  those  fetid  emanations  which  it  is  employed  to  correct 
in  the  chambers  of  the  sick. 

COMPOUNDS  OF  CARBON  WITH  OXYGEN. 

with  one  atom  or  half  a  volume  of  oxygen, 


One  atom  or 

one    volume 

of  carbon, 

equivalent  6, 


equivalent   8,   forms    one    atom   or  one 
volume  of  carbonic  oxide,  equivalent  14. 
with  two  atoms  or  one  volume  of  oxygen, 
equivalent  16,  forms  one  atom   or  one 


volume  of  carbonic  acid,  equivalent  22. 

1191.  Two  atoms  or  volumes  of  carbon,  equivalent  12, 
with  three  atoms  or  one  and  a  half,  volumes  of  oxygen, 
equivalent  24,  form  one  atom  of  oxalic  acid,  equivalent  36. 

1192.  Two  other  compounds  of  carbon  with  oxygen  are 
alleged  to  exist;  one  called  mellitic,  the  other  croconic  acid. 
The  former  contains  four  atoms  of  carbon  to  three  of  oxy- 
gen; the  latter  five  of  carbon  to  four  of  oxygen. 

Of  Carbonic  Oxide. 

1193.  Preparation. — This  compound  is  produced  by  the 
combustion  of  carbon  with  an  inadequate  supply  of  oxy- 
gen; or  when  bodies  containing  carbonic  acid  are  heated 
with   certain  substances  having  an  affinity   for   oxygen. 
Thus  it  may  be  procured  by  heating  carbonate  of  lime 
with  iron  filings.     The  best  process,  however,  for  obtain- 
ing carbonic  oxide  in  a  state  of  purity,  is  to  heat  five  parts 
of  concentrated  sulphuric  acid  with  one  of  oxalic  acid; 
which,  being  deprived  by  the  sulphuric  acid  of  the  water 
which  is  essential  to  its  existence,  is  resolved  into  car- 
bonic oxide  and  carbonic  acid.     The  latter  gas  may  be 
removed  by  lime-water,  leaving  the  carbonic  oxide  in  a 
state  of  purity. 

Apparatus  for  separating  Carbonic  Acid  from  Carbonic  Oxide,  oy  means  of  Lime-water. 

1194.  This  apparatus  is  represented  by  the  opposite  engraving.  Lime-water  being 
introduced  in  sufficient  quantity  into  the  inverted  bell  glass,  another  smaller  bell 
glass,  C,  is  supported  within  it  as  represented  in  the  engraving.  Both  of  the  bells 
have  perforated  necks.  The  inverted  bell  is  furnished  with  a  brass  cap  having  a 
stuffing  box  attached  to  it,  through  which  the  tube,  D,  of  copper,  slides  air-tight. 
About  the  lower  end  of  this  tube,  the  neck  of  a  gum  elastic  bag  is  tied;  so  that  the 
cavity  of  the  bag  may  communicate  with  that  of  the  tube.  The  neck  of  the  other 
bell  is  furnished  with  a  cap  and  cock,  surmounted  by  a  gallows  screw,  by  means  of 
which  the  leaden  pipe,  P  P,  with  a  brass  knob  at  the  end  suitably  perforated,  may 
be  fastened  to  it,  or  removed  at  any  moment.  Suppose  this  pipe,  by  aid  of  another 
brass  knob  at  the  other  extremity,  to  be  attached  to  the  perforated  neck  of  a  very 
tall  bell  glass  filled  with  water  upon  a  shelf  of  the  pneumatic  cistern :  on  opening 


Apparatus  for  separating  Carbonic  Acid  from  Carbonic  Oxide,  by 
Means  of  Lime-water. 


(Page  224.) 


CARBON.  ' 225 

a  communication  between  the  bells,  the  water  will  subside  in  the  tall  bell  glass  over 
the  cistern,  and  the  air  of  the  bell  glass,  C,  being  drawn  into  it,  the  lime-water  will 
rise  into  and  partially  occupy  the  space  within  the  latter.  As  soon  as  this  is  ef- 
fected, the  cocks  must  be  closed,  and  the  tall  bell  glass  replaced  by  a  small  one 
filled  with  water,  and  furnished  with  a  gallows  screw  and  cock.  This  bell  being  at- 
tached to  the  knob  of  the  lead  pipe,  to  which  the  tall  bell  had  been  fastened  before, 
the  apparatus  is  ready  for  use.  I  have  employed  it  in  the  new  process  for  obtaining 
carbonic  oxide  from  oxalic  acid,  by  digestion  with  sulphuric  acid  in  a  glass  retort. 
The  gaseous  product  consists  of  equal  volumes  of  carbonic  oxide  and  carbonic  acid, 
which,  being  received  into  a  bell  glass,  communicating,  as  above  described,  by  a  pipe 
with  the  bell  glass,  C,  may  be  transferred  into  the  latter,  through  the  pipe,  by  open- 
ing the  cocks.  As  the  gaseous  mixture  enters  the  bell,  C,  the  lime-water  subsides. 
As  soon  as  a  sufficient  quantity  of  the  gas  has  entered,  the  gaseous  mixture,  by  means 
of  the  gum  elastic  bag  and  the  hand,  may  be  subjected  to  repeated  jets  of  lime-water, 
and  thus  depurated  of  all  the  carbonic  acid.  By  raising  the  liquid  in  the  outer  bell, 
A,  the  purified  carbonic  oxide  may  be  propelled  through  the  cock  and  lead  pipe,  into 
any  vessel  to  which  it  may  be  desirable  to  have  it  transferred. 

1195.  Properties  of  Carbonic  Oxide. — Carbonic  oxide  is 
a  colourless,  insipid  gas,  indecomposable  by  heat  or  elec- 
tricity, and  incapable  of  reddening  litmus.      Its  specific 
gravity  is  0.9727.     It  does  not  support  combustion,  and  is 
destructive  to  life.     It  burns  with  a  feeble  blue  flame,  and, 
combining  with  oxygen,  is  converted  into  carbonic  acid. 
By  platinum  sponge,  a  mixture  of  oxygen  and  carbonic 
oxide  is  gradually  changed  into  carbonic  acid. 

Experimental  Illustrations. 

1196.  Carbonic  oxide  gas,  evolved  from  oxalic  acid  by 
the  process  abovementioned,  and  collected  in  bell  glasses 
over  water.     Combustion  and  detonation  of  it  with  oxy- 
gen gas,  effected  by  means  of  a  sliding-rod  eudiometer,  or 
volumescope.     Subsequent  absorption  of  the  resulting  car- 
bonic acid  by  lime-water,  shown. 

Of  Carbonic  Acid. 

1197.  The  proportion  of  this  gas,  existing  in  the  atmos- 
phere, is  much  less  than  was  formerly  supposed ;  being,  ac- 
cording to  some  experiments  of  Thenard,  not  more  than  a 
thousandth  part.      It  is  this  portion,  however,  that  pro- 
duces the  pellicle  on  lime-water,  during  its  exposure  to  the 
air,  and  which,  under  like  circumstances,  by  combining 
with  the  alkalies,  enables  them  to  effervesce  with  acids. 
Carbonic  acid  is  incessantly  a  product  of  combustion  and 
of  the  respiration  of  animals.     It  is  a  principal  ingredient 
in  marble  and  limestone. 

1198.  Preparation. — Carbonic  acid  may  be  evolved  from 

29 


226  INORGANIC  CHEMISTRY. 

any  carbonate  by  heat  or  by  acids.  It  is  usually  procured 
for  the  impregnation  of  water,  by  the  superior  affinity  of 
sulphuric  acid  for  the  lime  in  marble.  Excepting  that  it  is 
more  costly,  chlorohydric  acid  is  preferable  for  this  pur- 
pose; as  the  chloride  of  calcium,  being  very  soluble,  does 
not,  like  the  sulphate,  clog  the  vessels. 

1199.  Carbonic  acid  is  evolved  copiously  during  the  vi- 
nous fermentation. 

1200.  The  process  and  the  self-regulating  reservoirs, 
already  described,  (796,  &c.)  may  be  resorted  to  for  car- 
bonic acid,  substituting  lumps  of  marble  for  zinc.     The 
best  materials  for  the  evolution  of  this  gas,  agreeably  to 
my  experience,  are  chlorohydric  acid  and  calcareous  sta- 
lactites, or  clam  shells. 

1201.  Carbonic   acid   might  be   procured  at  a  trifling 
cost,  by  drawing,  by  the  aid  of  a  suction  pump,  the  efflu- 
vium of  burning  charcoal  through  water  to  deprive  it  of 
dust,  and  then  forcing  it  into  the  cavities  in  which  its  pre- 
sence may  be  desirable. 

1202.  This  process  for  the  production  and  employment 
of  carbonic  acid,  generated  by  the  combustion  of  charcoal, 
is  illustrated  in  the  small  way  by  the  following  engraving 
and  description. 

Combustion  of  Charcoal  or  other  Combustibles  in  Oxygen  Gas. 


1203.  The  preceding  cut  represents  an  apparatus  which  I  have  contrived  for  ex- 
hibiting the  combustion  of  charcoal,  or  other  combustibles,  in  oxygen  gas.  Two 
large  glass  bells.  A,  B,  each  furnished  with  a  tubulure  at  the  apex,  are  associated  by 


CARBON.  227 

means  of  the  pipe,  P,  which,  in  one  of  the  bells,  B,  communicates  with  a  tube,  ex- 
tending about  five  inches  within  the  bell,  below  its  neck,  so  as  to  reach  into  some 
lime-water,  or  an  infusion  of  litmus,  contained  in  a  glass  vessel,  resting  on  a  stand, 
as  represented  in  the  figure.  The  wooden  stand  which  holds  the  glass  vessel,  and 
the  iron  stand  which  supports  the  coal  in  the  bell,  A,  must  be  previously  placed  on 
(he  shelf  of  the  pneumatic  cistern,  as  represented  in  the  cut;  so  that  A,  when  in- 
cluding the  coal,  may  be  over  the  mouth  of  the  cock,  D,  which  communicates  with 
one  of  the  gas  holders,  situated  under  the  shelves  of  the  pneumatic  cistern,  which, 
for  this  experiment,  should  be  filled  with  oxygen. 

1204.  Into  the  bell  glass  in  which  the  vessel  is  placed,  a  pipe  from  the  suction  pump 
of  the  hydrostatic  blowpipe  is  made  to  enter,  and  reach  nearly  to  the  stand.  The 
apparatus  having  been  prepared  thus  far,  the  bells  must  be  lifted  so  as  to  permit  a 
live  coal  to  be  put  upon  the  iron  stand,  as  represented  in  the  figure.  As  soon  as 
they  are  restored  to  their  previous  situations,  the  suction  pump  must  be  put  into 
operation,  and  the  cock,  D,  of  the  gas  holder,  containing  the  oxygen,  opened;  so  as 
to  allow  a  current  of  the  gas  to  have  access  to  the  coal,  by  replacing  the  air,  which 
is  withdrawn  by  the  pump  through  the  pipes,  P  and  E.  The  coal  burns  splendidly; 
and  as  the  oxygen  becomes  saturated,  it  is  drawn  off  by  the  suction  pump,  being 
made,  in  its  way  from  A  to  B,  to  pass  through  the  liquid  in  the  vessel,  into  which 
descends  the  tube  proceeding  from  A.  If  the  liquid  be  water  tinged  with  litmus,  it 
will  become  red  by  the  action  of  the  carbonic  acid :  if  it  be  lime-water,  a  copious 
milky  precipitate  will  appear. 

1205.  Properties  of  Carbonic  Acid. — It  is  a  colourless 
gas,  with  a  pungent  smell  and  an  acid  taste.    Water  takes 
up  its  own  bulk  of  this  gas,  whatever  may  be  its  density.    It 
combines  with  earths,  alkalies,  and  metallic  oxides,  form- 
ing with  lime,  baryta,  strontia,  magnesia,  and  oxide  of 
lead,  compounds  which  are  insoluble.     Hence  it  precipi- 
tates lime-water,  barytic-water,  and  solution  of  acetate  of 
lead.     Litmus  is  reddened  by  this  acid.     It  destroys  life 
and  extinguishes  flame,  but  is  not  insalubrious  to  breathe 
when  much  diluted  with  air. 

1206.  Carbonic  acid  is  very  antiseptic.     When  concen- 
trated in  water  it  is  grateful  to  the  stomach.     Potassium 
burns  in  this  gas,  absorbing  oxygen  and  precipitating  car- 
bon.    Plants  probably  absorb  it,  retain  its  carbon,  and 
give  out  its  oxygen.     The  respiration  of  animals  tends 
to  compensate  this  change,  by  carbonizing  the  oxygen  of 
the  air. 

1207.  Carbonic  acid  is  heavier  than  atmospheric  air, 
its  specific  gravity  being  1,5239.     At  the  temperature  of 
32°,  and  under  a  pressure  of  forty  atmospheres,  it  con- 
denses into  a  colourless  liquid. 

Experimental  Illustrations. 

1208.  Evolution  of  the  gas  shown;  also  its  property  of 
extinguishing  a  candle.     That  it  differs  from  nitrogen, 
made  evident  by  means  of  lime-water.     Litmus,  reddened 
by  carbonated  water,  and  restored  to  its  original  colour 
by  boiling. 


228 


INORGANIC  CHEMISTRY. 


1209.    Analysis   of  mixtures    containing   the    gas,   by 
means  of  the  sliding-rod  eudiometer  and  lime-water. 

Apparatus  for  shoioing  some  of  the  distinguishing  Properties  of  Carbonic  Add  Gas. 

1210.  Having    introduced    into    the 
three-necked  bottle,  represented  in  the 
adjoining  figure,  one  or  two  ounces  of 
carbonate  of  ammonia,  add  about  half 
as  much  nitroso-nitric  acid.  (1017.)    An 
active  effervescence  will  ensue,  arising 
from  the  expulsion  of  the  carbonic  acid 
from  the  ammonia,  by  the  stronger  af- 
finity of  the  nitric  acid.     At  the  same 
time,  sufficient  fume  will  be  generated 
to  make  it  evident  how  far  the  vessels 
are  occupied  by  the  gas,  to  the  exclu- 
sion of  atmospheric  air.    By  these  means 
the  movements  of  the  carbonic  acid  gas 
will  be  recognised  as  ascending  to  the 
upper   vessel,   which    it   will    fill,    and 
finally  overflow  through  the  crevice  be- 
tween the  brim  and  cover. 

1211.  The   cover   being  removed,   a 
lighted  candle  will  cease  to  burn,  when 
lowered   into  the  fume  indicating  the 
space  occupied  by  the  gas.     This  space 
will  comprise  the  whole  cavity  of  the 
vessel,  so  long  as  the  aperture,  A,  is 
closed ;  but,  on  removing  the  cork  from 
this  aperture,  the  gas  will  flow  out,  and 
the  stream,  marked  by  the  accompany- 
ing fume,  will  be  seen  descending  to- 
wards the  table,  and  will  extinguish  the 
flame  of  a  candle  if  made  to  encounter 
it;  or,  it  may  be  received  into  a  mug, 

so  as  to  arrest  the  combustion  of  a  taper  introduced  into  it,  or  upon  which  the  con- 
tents of  the  mug  may  be  poured.  Under  these  circumstances,  a  taper  will  burn  any- 
where within  the  vessel,  V,  if  it  be  not  below  the  aperture,  A,  above  which  the  gas 
is  not  now  seen  to  extend  itself.  But  if  one  of  the  orifices  of  the  bottle  be  opened, 
the  carbonic  acid  will  be  found  entirely  to  desert  the  upper  vessel. 

1212.  It  will  thus  be  made  evident  that  this  gas,  from  its  greater  specific  gravity, 
has,  in  the  atmosphere,  some  of  the  habitudes  of  liquids ;  while  its  incapacity  to 
support  combustion  will  be  demonstrated. 

1213.  The  specific   gravity  of  carbonic  acid  being  rather  more  than  one-half 
greater  than  that  of  atmospheric  air,  it  does  not  speedily  leave  any  cavity  in  which 
it  may  be  introduced.     It  is  on  this  account  that  persons  often  perish  on  entering 
wells. 

Impregnation  of  Water  with  Carbonic  Add. 

1214.  The  process  by  which  water  is  impregnated  with  carbonic  acid,  may  be 
easily  understood  from  the  following  engraving. 

1215.  A  condenser,  A,  is  fastened  at  bottom  into  a  block  of  brass,  which  is  fur- 
nished with  a  conical  brass  screw,  by  means  of  which  it  is  easily  attached  firmly  to 
the  floor.     In  this  brass  block  are  cavities  for  the  two  valves,  one  opening  inwards 
from  the  pipe,  B,  the  other  outwards  towards  the  pipe,  C.     The  pipe,  B,  commu- 
nicates with  a  self-regulating  reservoir  of  carbonic  acid. 

1216.  The  gas  which  the  condenser  draws  in  from  the  reservoir,  is  forced  through 
the  other  pipe  into  a  strong  copper  vessel,  in  which  the  water  is  situated,  and  which 
is  represented  in  the  figure,  as  if  the  front  part  were  removed,  in  order  to  expose  the 
inside  to  inspection. 

1217.  If  the  vessel  and  its  contents  be  thoroughly  exhausted  of  air  before  the  im- 
pregnation is  commenced,  the  water  will  take  up  as  many  times  its  bulk  of  gas,  as 
the  pressure  employed  exceeds  that  of  the  atmosphere. 

1218   When  duly  saturated,  the  water  may  be  withdrawn  nt.  pleasure  by  means  of 


CARBON. 


229 


the  syphon,  D,  of  which  one  leg  descends  from  the  vertex  of  the  vessel  to  the  bot- 
tom, while  the  other  is  conveniently  situated  for  filling  a  goblet. 


Of  the  Liquefaction  and  Solidification  of  Carbonic  Add. 

1219.  It  has  been  shown  that  the  extrication  of  carbonic  acid  from  a  base, 
may  be  checked  by  the  pressure  consequent  to  confinement,  (242,)  and  it  has 
been  mentioned  that  Faraday  obtained  this  acid  in  a  liquid  state,  by  causing 
the  materials  for  the  generation  of  it  to  react  within  a  glass  tube,  sealed  her- 
metically after  their  introduction.    Subsequently,  the  liquefaction  of  this  acid 
was  accomplished  on  a  much  larger  scale  by  Brunei;  and  in  1836,  thirteen 
years  after  the  date  of  Faraday's  observations,  Thillorier  caused  not  only 
the  liquefaction,  but  the  solidification  of  the  acid.     Without  any   other 
knowledge  than  that  afforded  by  brief  notice,  or  verbal  information  con- 
veyed by  travellers,  my  friend,  Dr.  Mitchell,  was  quite  successful  in  the 
repetition  of  the  processes  of  Thillorier.     The  production  of  the  solid  acid 
is  dependent  on  the  same  principles  as  the  congelation  of  water  in  the  cryo- 
phorus  and  in  Leslie's  experiment.  (309,  &c.) 

1220.  The  pressure  requisite  to  retain  carbonic  acid  in  a  state  of  liquidity, 
is  at  4°  below  zero,  26  atmospheres;  at  32°,  36  atmospheres;  at  86°,  75 
atmospheres.  (196.)    Its  specific  gravity  is,  at  that  temperature,  about  830. 
The  density  of  the  gas  which  occupies  the  cavity  above  the  liquid  portion 
of  the  acid,  is  130  times  the  density  of  that  which  it  has  at  the  mean  baro- 
metric pressure  of  30  inches  of  mercury. 

1221.  Liquid  carbonic  acid  does  not  combine,  nor  even  mingle,  with 
water  or  fixed  oils;  but,  under  the  requisite  pressure,  combines  readily  with 
ether,  alcohol,  naphtha,  or  oil  of  turpentine.     It  may  be  decomposed  by 
potassium,  but  not  by  zinc,  iron,  or  other  metals  proper. 

1222.  One  of  the  most  interesting  properties  of  the  acid,  is  that  intense 
cold  produced  by  its  assuming  the  aeriform  state,  to  which  allusion  has 
been  made.     A  jet  of  it  depressed  a  thermometer  to  130°  below  zero,  F. 
The  cold  by  which  the  acid  is  frozen,  or  in  other  words,  its  freezing  point, 
is  estimated  at  148°  below  zero,  F.     According  to  Mitchell,  one  drachm  of 


230  INORGANIC  CHEMISTRY. 

solid  acid  is  yielded  by  each  ounce  of  the  liquid.  I  will  here  give  Dr. 
Mitchell's  description  of  this  wonderful  product  of  chemical  art,  in  his  own 
words  :* 

1223.  "  The  porosity  and  volatile  character  of  the  solid  renders  its  specific 
gravity  of  difficult  ascertainment.     When  recently  formed  it  is  about  the 
weight  of  carbonate  of  magnesia,  and  when  strongly  compressed  by  the 
firigers,  its  density  is  nearly  doubled.     Solid  carbonic  acid  is  of  a  perfect 
whiteness,  and  of  a  soft  and  spongy  texture,  very  like  slightly  moistened 
and  aggregated  snow.     It  evaporates  rapidly,  becoming  thereby  colder  and 
colder;  but  the  coldness  produced  seems  to  steadily  lessen  the  evaporation, 
so  that  the  mass  may  be  kept  for  some  time.     A  quantity  weighing  346 
grains  lost  from  3  to  4  grains  per  minute  at  first,  but  did  not  entirely  dis- 
appear for  3  hours  and  a  half.     The  natural  temperature  was  76°  —  79°. 
The  solid  is  most  easily  kept  when  compressed  and  rolled  up  in  cotton  or 
wool.     Its  temperature  when  newly  formed  is  not  exactly  ascertainable  be- 
cause it  is  immediately  lowered  by  evaporation.     Thillorier  seems  to  have 
entertained  the  opinion  that  the  greatest  degree  of  cold  was  created  at  the 
time  of  the  formation  of  the  solid.     In  my  experiments  a  constant  decrease 
of  temperature  was  observed ;  which  was  accelerated  by  a  current  of  air, 
or  any  other  means  of  augmenting  evaporation.     At  its  formation,  the  car- 
bonic snow  depresses  the  thermometer  to  about  —  85°.     If  it  be  confined 
in  wool  or  raw  cotton,  its  cooling  influence  is  retarded ;  if  it  be  exposed  to 
the  air,  especially  when  in  motion,  the  thermometer  descends  much  more 
rapidly  ,*  and  under  the  receiver  of  an  air  pump,  the  effect  is  at  its  maxi- 
mum.    The  greatest  cold  produced  by  the  solid  carbonic  acid  in  the  air  was 
—  109°,  under  an  exhausted  receiver  —  136°,  the  natural  temperature  be- 
ing at  +  86°. 

1224.  "  The  admixture  of  sulphuric  ether  so  as  to  produce  the  appearance 
of  wet  snow,  increased  the  coldness,  for  the  temperature  then  fell,  under 
exhaustion,  to  — 146,*  a  degree  of  cold  which  we  were  not  able  to  exceed 
by  means  of  any  variation  of  the  experiment.     That  result  is  most  easily 
obtained  by  putting  about  two  fluid  drachms  of  ether  into  the  iron  receiver 
before  charging  it.     A  compound  liquid  may  be  thus  formed  which  yields 
a  snow  in  less  quantity,  but  of  a  more  facile  refrigeration.     Alcohol  may 
replace  ether  in  either  mode,  but  with  less  decided  effect.     In  the  air  the 
alcoholic  mixture  fell  to  — 106°  and  remained  stationary.     By  blowing  the 
breath  on  it,  it  fell  to  -—110°.     Left  to  itself  it  rose  slowly  to  —106° ;  but 
on  being  placed  under  an  exhausted  receiver  fell  to  — 134°. 

1225.  "  Every  attempt  to  wet  the  carbonic  solid  with  water,  failed,  so  that 
no  estimate  of  its  relative  effects  could  be  made. 

1226.  "  The  experiments  resulting  from  the  great  coldness  of  the  new 
solid,  were  very  striking.    Mercury  placed  in  a  cavity  in  it,  and  covered  up 
with  the  same  substance,  was  frozen  in  a  few  seconds.     But  the  solidifica- 
tion of  the  mercury  was  almost  instantly  produced  by  pouring  it  into  a 
paste  made  by  the  addition  of  a  little  ether.     Frozen  mercury  is  like  lead, 
soft  and  easily  cut.     It  is  ductile,  malleable,  and  insonorous.     Just  as  it  is 
about  to  melt,  it  becomes  brittle  or  '  short'  and  breaks  under  the  point  of  a 
knife.     These  facts  may  account  for  the  discrepancies  of  authors  on  this 
subject.     Frozen  mercury  sinks  readily  in  liquid  mercury. 

1227.  "  At  about  —  110°  liquid  sulphurous  acid  is  frozen,  and  the  ice 

*  For  engraving  and  description  of  Mitchell's  modification  of  Thillorier's  appara- 
tus, see  Appendix. 


CARBON.  231 

sinks  in  its  own  liquid,  and  at  —  130°  alcohol  of  .798,  assumes  a  viscid 
and  oily  appearance,  which  by  increase  of  cold,  is  augmented  until  at 
—  146°  it  is  like  melted  wax.  Alcohol  of  .820  froze  readily.  At  —  146° 
sulphuric  ether  is  not  in  the  slightest  degree  altered. 

1228.  "When  a  piece  of  solid  carbonic  acid  is  pressed  against  a  living 
animal  surface,  it  drives  off  the  circulating  fluids  and  produces  a  ghastly 
white  spot.     If  held  for  15  seconds  it  raises  a  blister,  and  if  the  application 
be  continued  for  two  minutes  a  deep  white  depression  with  an  elevated  mar- 
gin is  perceived ;  the  part  is  killed,  and  a  slough  is  in  time  the  consequence. 
I  have  thus  produced  both  blisters  and  sloughs,  by  means  nearly  as  prompt 
as  fire,  but  much  less  alarming  to  my  patients." 

Of  Oxalic  Acid, 

1229.  Latterly  oxalic  acid,  long  known  as  a  product  of 
vegetation,  has  been  found  to  belong  to  the  compounds  of 
carbon  with  oxygen ;  and  still  more  lately  mellitic  and  cro- 
conic  acid  have  been  added  to  this  class.     Yet  when  the 
necessity  of  water  to  the  existence  of  these  acids  is  taken 
into  view,  it  appears  to  rne  questionable  whether  they  may 
not  be  considered  as  acids  with  a  compound  radical,  con- 
sisting of  hydrogen  and  carbon. 

1230.  Preparation. — Oxalic  acid  may  be  obtained  from 
the  common  sorrel,  Rumex  acetosa,  or  from  the  wood  sorrel, 
Oxalis  acetosella,  from  which  it  derives  its  name.     In  these 
plants  it  exists  in  the  state  of  binoxalate  of  potash.     It  may 
also  be  procured  by  the  reaction  of  one  part  of  sugar  with 
six  of  nitric  acid.     The  weight  of  the  acid  obtained   is 
equal  to  three-eighths  of  the  materials.     Wood,  glue,  silk, 
or  hair  may  be  substituted  for  sugar  in  this  process ;  but 
when  these  substances  are  used,  the  product  is  impure. 
Next  to  sugar,  starch  and  molasses  are  probably  the  best 
materials.    Oxalic  acid  may  be  procured  also,  by  digesting 
shavings  of  wood  in  a  solution  of  caustic  potash,  at  a  heat 
considerably  above  that  of  boiling  water. 

1231.  Properties. — Oxalic  acid  is  a  solid,  but  soluble  both 
in  water  and  alcohol,  the  resulting  solutions  being  extremely 
sour.     One  grain  in  half  a  pint  of  water  is  sufficient  to 
redden  litmus  distinctly.     It  cannot  exist  uncombined  with 
water  or  some  other  base.     The  atomic  composition  of 
this  acid  would  authorize  us  to  consider  it  as  a  binary 
compound  of  carbonic  acid  and  carbonic  oxide.     In  every 
atom  of  oxalic  acid   in  its  appropriate  crystalline  form, 
there  are  three  atoms  of  water.     When  these  crystals  are 
exposed  to  an  unusually  dry  atmosphere,  or  to  a  tempera- 
ture of  80°,  a  partial  efflorescence  ensues ;  and  if  the  heat 


232  INORGANIC  CHEMISTRY. 

be  raised  to  212°,  they  part  with  two  atoms  of  water, 
which  they  recover  on  exposure  to  the  air  after  cooling. 
When  heated  to  300°,  the  acid  is  decomposed. 

1232.  Oxalic  acid  is  an  energetic  poison.     The  best  an- 
tidotes for  it  are  magnesia,  or  the  calcareous  carbonates 
in  the  pulverulent  form,  especially  chalk.     When  oxalic 
acid  meets  with  either  of  these  bases,  an  insoluble  and 
inert  oxalate  is  formed.     Hence  its  employment  as  a  test 
for  lime. 

1233.  It  appears  from  statements  made  by  Vogel  in  the 
Journale  de  Pharmacie,  for  April,  1836,  that  the  protoxides 
of  iron  and  copper  are  precipitated  from  their  union  with 
sulphuric  acid  by  oxalic  acid.     The  oxalate  of  iron  is  yel- 
low; the  oxalate  of  copper,  blue.     Both  are  insoluble  in 
water. 

Of  Mellitic  Acid. 

1234.  Mellitic  acid  is  obtained  in  crystals  from  a  rare 
mineral,  called  the  honey-stone,  which  is  a  mellitate  of 
alumina.     It  is  soluble  in  water  and  alcohol,  and  has  a 
sour  taste. 

Of  Croconic  Acid. 

1235.  Croconic  acid  may  be  procured  in  yellow  crystals, 
from  the  croconate  of  potash,  which  is  generated  in  the  pro- 
cess for  obtaining  potassium  by  means  of  charcoal.     It  is 
inodorous,  has  an  acid  and  astringent  taste,  and  reddens 
litmus. 

COMPOUNDS  OF  CARBON  WITH  OXYGEN  AND  CHLORINE. 

1236.  There  are  two  compounds  of  carbon  with  oxygen  and  chlorine. 
To  one  of  these,  which  has  been  recently  discovered,  the  name  of  chloral 
has  been  given ;  to  .the  other,  that  of  chlorocarbonic  or  chloroxycarbonic 
acid.     The  latter  name  is  preferable;  as  the  other  would  convey  the  idea 
of  an  acid  made  solely  by  the  union  of  chlorine  with  carbon. 

Of  Chloral. 

1237.  When  chlorine  is  passed  through  alcohol,  which  consists  of  hy- 
drogen, oxygen,  and  carbon,  one  portion  combines  with  hydrogen,  forming 
chlorohydric  acid,  while  another  combines  with  oxygen  and  carbon,  form- 
ing chloral. 

1238.  Chloral  is  described  as  a  colourless  transparent  liquid  with  a  pun- 
gent odour.     Its  specific  gravity  is  1.502.     It  boils  at  201°,  and  may  be 
distilled  unchanged.     With  water  it  forms  a  white  crystalline  mass,  appa- 
rently a  hydrate. 


CARBON.  233 

1239.  Chloral  consists  of  nine  atoms  of  carbon,  four  of  oxygen,  and  six 
of  chlorine. 

Of  Chloroxy carbonic  Acid. 

1240.  When  one  volume  of  dry  chlorine  and  one  volume  of  carbonic 
oxide  gas  are  mingled,  and  exposed  to  the  solar  rays,  they  combine,  and 
condense  into  one  volume  of  a  colourless  acid  gas,  to  which  the  name  of 
chloroxycarbonic  acid  has  been  given.     It  is  exceedingly  offensive  to  the 
eves  and  to  the  organs  of  respiration.     It  reddens  litmus  paper,  and  with 
ammonia  forms  a  white  salt.     By  contact  with  water  a  reciprocal  decom- 
position ensues,  and  chlorohydric  and  carbonic  acids  are  produced.     It  con- 
sists of  one  atom  of  chlorine,  and  one  atom  of  carbonic  oxide. 

Of  the  Chlorides  of  Carbon. 

1241.  Chlorine  forms  four  compounds  with  carbon.     The  dichloride  is 
a  white  crystalline  inflammable  solid,  having  a  peculiar  odour,  resembling 
that  of  spermaceti.     At  250°  it  sublimes  in  crystals.     It  is  fusible  by  heat, 
and  boils  at  a  temperature  between  350°  and  450°.     The  dichloride  con- 
sists of  one  atom  of  chlorine  and  two  of  carbon. 

1242.  When  the  liquid,  produced  by  the  union  of  chlorine  with  olefiant 
gas,  called  bichlorine  ether,  is  exposed  to  the  sun,  in  contact  with  a  suffi- 
cient quantity  of  chlorine,  the  sesqitichloride  of  carbon  is  produced.     It  is 
a  colourless,  transparent,  friable,  crystalline  body,  nearly  tasteless,  and  re- 
sembling camphor  in  smell.     While  exposed  to  the  flame  of  a  spirit  lamp, 
it  burns  with  a  red  flame,  but  the  combustion  ceases  as  soon  as  the  lamp 
is  removed.     It  melts  at  320°,  and  at  360°  is  converted  into  vapour,  which 
may  be  condensed  without  decomposition.     It  is  nearly  twice  as  heavy  as 
water.     The  sesquichloride  of  carbon  consists  of  three  atoms  of  chlorine 
and  two  atoms  of  carbon. 

1243.  The  protochloride  is  obtained  by  passing  the  sesquichloride  in 
vapour  through  a  red-hot  porcelain  tube.     The  sesquichloride  is  decom- 
posed into  the  protochloride  and  chlorine.     The  protochloride  is  a  transpa- 
rent, colourless  liquid,  with  a  specific  gravity  of  1.4875.    It  is  composed  of 
one  atom  of  chlorine  and  one  of  carbon. 

1244.  All  the  above  described  chlorides  are  insoluble  in  water,  acids,  and 
alkalies;  but  are  soluble  in  oils,  alcohol,  and  ether.    When  chloral  is  boiled 
in  a  solution  of  potash,  a  decomposition  ensues,  and  a  chloride  of  carbon 
is  evolved  in  vapour,  and  may  be  condensed  in  a  receiver.     This  chloride 
is  a  colourless,  transparent  liquid,  with  an  odour  similar  to  that  of  chloric 
ether.     Its  specific  gravity  is  1.48.     This  chloride  consists  of  five  atoms  of 
chlorine  and  four  of  carbon. 

Of  Bromide  of  Carbon. 

1245.  When  bromine  is  brought  in  contact  with  half  its  weight  of  per- 
iodide  of  carbon,  heat  is  evolved,  a  decomposition  ensues,  and  bromides  of 
iodine  and  carbon  are  formed.  The  bromide  of  carbon  is  a  volatile,  colour- 
less liquid,  of  a  sweet  taste,  and  an  ethereal  odour. 

Of  the  Iodides  of  Carbon. 

1246.  The  protiodide  of  carbon  is  a  liquid,  in  properties  strongly  re- 
sembling the  bromide  of  carbon.     The  periodide  appears  under  the  form 

30 


234  INORGANIC  CHEMISTRY. 

of  yellow  crystalline  scales,  which  have  a  sweet  taste,  a  strong  aromatic 
smell  resembling  that  of  saffron,  and  a  specific  gravity  higher  than  that  of 
water. 

Of  Sulphocarbonic  Acid,  or  Bisulphide  of  Carbon. 

1247.  The  bisulphide  of  carbon  is  obtained  by  passing  the  vapour  of 
sulphur  over  charcoal  heated  to  incandescence  in  a  porcelain  tube.     It  is  a 
transparent,  colourless,  volatile  liquid,  possessing  an  acrid  taste,  and  a  pecu- 
liar nauseous  smell.     Its  specific  gravity  is  1.272.     It  boils  at  105°,  and 
does  not  freeze  at  —  60°.    At  a  temperature  a  little  above  the  boiling  point 
of  mercury,  it  inflames.     When  the  bulb  of  a  spirit  thermometer,  wrapped 
in  lint  imbued  with  this  liquid,  is  placed  within  a  receiver,  and  the  air  witfc' 
drawn,  the  temperature  falls  to  — 82°. 

1248.  This  compound  unites  with  almost  all  the  sulpho-bases,  forming 
with  them  sulpho-salts,  and  is  as  well  entitled  to  be  treated  as  an  acid,  as 
the  analogous  compound  formed  by  sulphur  with  hydrogen. 

1249.  Dr.  Thomson  supposes  that  the  solid  mass,  obtained  by  washing 
the  nitre  out  of  gunpowder,  is  probably  a  solid  sulphide  of  carbon. 

COMPOUNDS  OF  CARBON  WITH  HYDROGEN. 

1250.  Carbon  and  hydrogen  are  in  opposite  extremes, 
as  respects  their  susceptibility  of  the  aeriform  state.    Per 
se,  carbon  is  probably  more  difficult  of  volatilization  by 
heat,  than  any  other  substance  in  nature.     Hydrogen,  on 
the  other  hand,  as  far  as  our  experience  goes,  is  not  sus- 
ceptible of  condensation,  even  into  the  non-elastic  state  of 
fluidity.     There  is,  however,  a  powerful  affinity  between 
these  substances;  and  hence,  when  a  compound  which 
contains  them  is  subjected   to   heat,    they  are   made  to 
combine  in  various  proportions,  according  to  the  intensity 
of  the  ignition,  and  the  influence  exercised  by  the  nitro- 
gen, or  oxygen,  previously  in  combination  with  them. 

1251.  In  general,  the  compounds  of  carbon  with  hydro- 
gen are  distinguished  by  inflammability.     In  the  gaseous 
state  they  constitute,  when  ignited,  the  flame  of  candles, 
lamps,  gas  lights,  and  culinary  fires.     They  are  incapable 
of  supporting  life,  but  are  not  actively  noxious  when  di- 
luted with  the  air. 

1252.  The  gaseous  compounds  of  carbon  with  hydrogen 
are  obtained  by  the  destructive  distillation  of  bituminous 
coal,  wood,  oil,  tar,  and  other  inflammable  substances. 

1253.  The  illuminating  power  of  each  of  these  various 
kinds  of  gas,  seems  to  be  in  proportion  to  the  quantity  of 
carbon  contained  in  a  given  volume,  provided  there  be  an 
equivalent  supply  of  oxygen ;  but,  otherwise,  the  excess  of 
carbon  renders  the  flame  smoky.     Hence  the  greater  bril- 


CARBON.  235 

liancy  of  small  flames,  or  those  excited  by  a  current  of 
air,  as  in  the  Argand  lamp.  The  same  flame  which  in 
common  air  is  unpleasantly  fuliginous,  transferred  to  oxy- 
gen gas,  displays  a  perfect  brilliancy. 

1254.  The  known  compounds  of  carbon  with  hydrogen 
are  numerous  and  complicated ;  and  yet  it  is  probable  that 
many  exist  in  nature,  or  may  be  produced  by  art,  with 
which  we  are  at  present  unacquainted. 

1255.  We  have  had  occasion  to  state,  (1153,)  that  where  bodies  have,  in 
the  same  volume,  the  same  number  of  atoms  of  each  of  their  ingredients, 
and  yet  differ  in  their  properties,  they  are  said  to  be  isomeric,  from  to-eg 
equal,  pspoi;  part.     Compounds,  in  which  the  constituents  are  in  the  same 
ratio,  but  in  which  the  resulting  volumes  exist  in  different  degrees  of  con- 
densation, are  said  to  be  polymeric  with  respect  to  each  other,  from  notes 
many,  pupos  part.     The  last  term  is  applied  to  a  class  of  the  compounds  of 
carbon  with  hydrogen,  in  all  of  which  these  elements  exist  in  the  same 
ratio  of  atom  for  atom ;  yet  from  some  difference  in  the  mode  of  aggregation, 
or,  as  I  believe,  in  the  extent  and  modes  of  their  association  with  heat,  light, 
and  electricity,  their  degree  of  condensation  when  in  the  aeriform  state,  and 
their  properties  in  other  respects  are  quite  different. 

1256.  We  have  then  two  groups  of  the  carburets  of  hydrogen,  in  one  of 
which  diversity  of  properties  is  attended  by  a  corresponding  diversity  in  the 
ratio  of  the  carbon  to  the  hydrogen;  while  in  the  other  this  ratio  is  uni- 
form, although  the  properties  and  resulting  volumes  in  the  aeriform  state, 
differ.     In  the  first  group,  there  are  four  compounds. 

1257. — 1.  Light  carburetted  hydrogen,  or  fire  damp,  consisting  of  two 
volumes  or  atoms  of  hydrogen,  with  one  volume  or  atom  of  carbon. 

1258. — 2.  The  compound,  in  all  the  varieties  of  which  there  are  as 
many  atoms  of  one  element  as  of  the  other,  and  for  which  Dr.  Thomson 
proposes  the  name  of  carbohydrogen  as  a  generic  appellation. 

1259. — 3.  By  carburet  of  hydrogen,  in  which  six  atoms  of  carbon  are 
united  with  three  of  hydrogen. 

1260. — 4.  Naphthaline,  in  which  ten  atoms  of  carbon  are  combined 
with  four  atoms  of  hydrogen. 

1261.  The  second  group,  which  is  subordinate  to  the  first,  being  formed 
in  fact  by  the  ramifications  of  carbohydrogen,  comprises,  according  to  Dr. 
Thomson,  several  varieties,  which  he  designates  and  describes  as  follows : — 

1262. — 1st.  Protocarbohydrogen,  consisting  of  a  volume  of  carbon  and 
a  volume  of  hydrogen,  condensed  into  one  volume.  This  variety,  now 
called  mytheline,  has  been  lately  isolated  by  Dumas  and  Peligot,  by  distil- 
ling one  part  of  pyroxylic  spirit,  obtained  by  the  distillation  of  wood,  with 
two  parts  of  chlorohydric  acid,  and  three  of  sulphuric  acid;  when  an  ethe- 
real chlorohydrate  of  mytheline  results.  Subjected  to  a  red  heat,  this  ethe- 
real compound  is  resolved  into  chlorohydric  acid  gas,  and  mytheline  in  the 
gaseous  form.  Pyroxylic  spirit  is  considered  as  a  bihydrate  of  mytheline, 
being  procured  from  crude  pyroligneous  acid  by  distillation.  It  bears  the 
same  relation  to  mytheline  that  alcohol  docs  to  ethcrinc.  (1267.) 

1263. — 2d.  Dcntocarbohydrogen,  or  olejiant  gas,  consisting  of  two  vo- 
lumes of  carbon  and  two  of  hydrogen,  condensed  into  one  volume, 

1264. — 3d.   Tritocarbohydrogen,  consisting  of  three  volumes  of  carbon 


236  INORGANIC  CHEMISTRY. 

and  three  of  hydrogen,  condensed  into  one  volume.  This  is  by  Dr.  Thom- 
son considered  as  constituting  the  gas  evolved  from  oil,  which  was  by  Dai- 
ton  called  super-olefiant  gas. 

1265. — 4th.  Tetartocarbohydrogen,  consisting  of  four  volumes  of  car- 
bon, and  four  volumes  of  hydrogen,  condensed  into  one  volume. 

1266. — 5th.  Hexacarbohydrogen,  containing,  according  to  Thomson, 
six  volumes  of  each  element,  condensed  into  one  volume. 

1267.  Of  Ether ine. — Besides  these  compounds,  it  has  been  inferred,  by 
many  chemists,  that  there  is  a  liquid,  or  solid  compound,  formed  of  four 
volumes  or  atoms  of  carbon,  and  four  volumes  or  atoms  of  hydrogen,  con-^ 
densed  into  one  volume  or  atom.     This  has  been  called  etherine,  under  the 
idea  that  it  is  the  common  base  of  all  the  ethers,  forming  common  ether  by 
uniting  with  one  volume  of  aqueous  vapour,  alcohol,  by  uniting  with  two 
such  volumes,  and  the  various  ethers,  by  uniting  with  acids,  or  the  other  in- 
gredients, after  which  they  are  severally  named.    Etherine  would  of  course 
beisomeric  with  the  tetartocarbohydrogen  of  Dr.  Thomson.  (1265.) 

Of  Light  Carburetted  Hydrogen,  or  Fire  Damp. 

1268.  The  substance  distinguished  by  these  names  has  been  dignified 
by  a  variety  of  appellations,  among  which  are  heavy  inflammable  air,  car- 
buretted  hydrogen,  and  bihydroguret  of  carbon.      Dr.  Thomson  has,  in 
some  instances,  used  the  monosyllable  di  to  indicate  proportions  the  inverse 
of  those  indicated  by  the  monosyllable  bi.     Thus,  bichloride  of  carbon  would 
signify  two  atoms  of  chlorine  and  one  of  carbon,  while  dichloride  conveys 
the  idea  of  two  atoms  of  carbon  and  one  of  chlorine.     Consistently,  then,  I 
think,  Dr.  Thomson  should  have  called  this  gas,  a  dicarburet  of  hydrogen; 
as  the  proportions  of  its  constituents  are  the  inverse  of  those  in  the  bicarbu- 
ret.    This  gas  has  long  been  known  to  miners  of  bituminous  coal,  under  the 
name  of  fire  damp,  as  one  of  their  greatest  enemies.     It  is  liberated  co- 
piously from  cavities  in  the  coal,  in  which,  no  doubt,  in  many  instances,  it 
has  been  pent  for  ages.     It  is  also  evolved  from  the  mud  of  stagnant  waters, 
and  is  occasionally  emitted  from  fissures  in  the  earth.     There  is  no  good 
mode  of  forming  it  artificially.     It  is  a  colourless  gas,  of  course  irrespirable, 
but  having  more  than  a  negative  influence  in  destroying  life.     Its  specific 
gravity  is  0.5593. 

Of  the  Safety  Lamp. 

1269.  In  the  account  above  given  of  dicarburet  of  hydrogen,  it  was  mentioned  that 
it  was  in  mines  a  source  of  injury.     When  existing  in  the  air  beyond  a  certain  pro- 
portion, it  explodes   on  coming  into  contact  with  the  flame  of  a  lamp  or  candle. 
Hence,  as  artificial  light  is  necessary  in  mines  inaccessible  to  the  light  of  day,  the 
use  of  candles  or  lamps,  in  the  ordinary  way,  has  been  frequently  destructive  to  the 
workmen.     It  had,  of  course,  been  the  cause  of  great  misery  to  them,  and  of  em- 
barrassment to  the  proprietors  of  the  mines. 

1270.  In  order  to  avoid  the  risk  attending  the  use  of  lamps  or  candles  in  mining,  a 
"steel  mill"  had  been  resorted  to,  in  which  the  rapid  revolution  of  a  steel  wheel  against 
a  flint,  was  made  to  produce  a  succession  of  sparks,  and  of  course  a  feeble  light.     I 
believe  that  the  security  afforded  by  this  invention  was  imperfect,  and  the  light  in- 
sufficient.    Explosions  have  been  more  frequent  in  the  English  mines  of  late  years, 
probably  in  consequence  of  the  greater  extent  and  depth  to  which  they  are  excavated. 
While  under  the  painful  impression  made  by  some  recent  catastrophes  of  this  nature, 
in  which  many  miners  had  been  been  killed  or  mutilated,  Sir  H.  Davy  exerted  him- 
self to  discover  the  means  of  sustaining  flame  safely  within  explosive  gaseous  mix- 
tures.    He  soon  ascertained  that  his  object  might  be  effected  by  enclosing  the  flame 
in  a  cage  of  wire  gauze,  so  as  to  allow  of  no  communication  with  the  surroundino- 
medium,  which  does  not  take  place  through  the  meshes  of  the  gauze.     Owing  to  the 


CARBON. 


237 


cooling  power  of  the  wire,  the  mixture  cannot  pass  through  the  meshes  in  a  state  of 
combustion.     Of  course  the  inflammation  is  confined  within  the  wire  gauze. 

1271.  The  method  in  which  I  illustrate  the  operation  of  the  safety  lamp,  may  be 
easily  comprehended  from  the  following  figure.     The  lamp  is  seen  within  a  large 

glass  cylinder  upon  a  stool.  The  cy- 
linder is  closely  covered  by  a  lid, 
which  will  not  permit  the  passage  of 
air  between  it  and  the  cylinder,  and 
which  is  so  light  as  to  be  easily  blown 
oiF.  Excepting  the  cage  alluded  to 
above,  the  safety  lamp  does  not  dif- 
fer materially  from  those  which  are 
ordinarily  used.  The  upper  surface 
of  the  receptacle  for  the  oil,  forms 
the  bottom  of  the  cage,  which  is  so 
closely  fitted  to  it,  and  so  well  closed 
every  where,  as  to  allow  air  to  have 
access  to  the  flame  only  through  the 
meshes  of  the  wire  gauze.  The  cage 
is  enclosed  within  three  iron  rods, 
surmounted  by  a  cap,  to  which  a  ring 
for  holding  the  lamp  is  attached,  as 
seen  in  the  figure. 

1272.  If,  while  the  lamp  is  burning, 
as  represented  in  the  figure,  hydro- 
gen, either  pure  or  carburetted,  be 
allowed,  by  means  of  the  pipe,  to  en- 
ter the  glass  cylinder,  so  as  to  form 
with  the  air  in  it  an  explosive  mix- 
ture, there  will  nevertheless  be  no 
explosion.  It  will  be  found  that  as 
the  quantity  of  inflammable  gas  in- 
creases, the  flame  of  the  lamp  en- 
larges, until  it  reaches  the  wire 
gauze;  where  it  burns  more  or  less 
actively,  accordingly  as  the  supply 
of  atmospheric  air  is  greater  or  less. 
It  will,  under  these  circumstances, 
often  appear  as  if  the  combustion 
had  ceased;  but  on  increasing  the 
proportion  of  atmospheric  air,  the  flame  will  gradually  contract,  and  finally  settle 
upon  the  wick,  which  will  burn  as  at  first  when  the  supply  of  hydrogen  ceases. 

1273.  If  the  cage  be  removed  from  the  lamp,  and  the  experiment  repeated  in  all 
other  respects  as  at  ffrst,  an  explosion  will  ensue,  as  soon  as  a  sufficient  quantity  of 
hydrogen  is  allowed  to  enter  the  cylinder. 

Of  Deutocarbohydrogen,  or  Olefiant  Gas,  called  also  Carbu- 
retted Hydrogen,  and  Hydroguret  of  Carbon.  • 

1274.  This  gas  received  its  name  in  consequence  of  its 
being  condensed  with  chlorine  into  a  liquid,  having  an 
oleaginous  consistency,  although  otherwise  unlike  an  oil. 
It  was  discovered  in  the  year  1796.  It  may  be  obtained 
by  subjecting  a  mixture  of  five  parts  of  sulphuric  acid  with 
one  of  alcohol  to  heat  in  a  glass  retort.  It  is  invisible, 
and  possesses,  like  other  gases,  the  mechanical  properties 
of  atmospheric  air.  Its  specific  gravity  is  0.9808.  When 
drawn  into  the  lungs  it  produces  asphyxia.  It  burns  with 
great  splendour,  and  detonates  with  oxygen  with  such  vio- 
lence, that  without  some  precautions  it  is  dangerous  to 


238  INORGANIC  CHEMISTRY. 

analyze  it  by  the  usual  processes.  I  have  had  several 
eudiometers  broken  by  it,  but  have  latterly  avoided  that 
accident,  by  exploding  the  mixture  in  a  rarefied  state, 
into  which  it  is  easily  brought  in  some  of  the  instruments 
which  I  employ. 

1275.  The  analysis  may  be  performed  in  the  volume- 
scope  for  analyzing  the  air  by  means  of  hydrogen,  with  a 
degree  of  "accuracy  sufficient  for  the  purpose  of  illustra- 
tion. Four  volumes  of  oxygen  should  be  added  to  one  of 
the  gas.  The  ignition  being  effected  as  already  described 
in  the  case  of  pure  hydrogen,  it  will  be  seen  that  the  five 
volumes  are  reduced  to  less  than  three,  and  that  by  the 
introduction  of  lime-water,  these  three  may  be  reduced  to 
one  residual  volume  of  oxygen.  The  reason  why  the  re- 
sidual gas  is  less  than  three  volumes,  is,  that  the  carbonic 
acid  formed  is  partially  absorbed  by  the  water.  As  the 
gas  contains  in  one  volume,  two  volumes  of  hydrogen,  and 
two  of  carbon  vapour,  it  will,  for  the  latter,  require  two 
volumes;  for  the  former,  one  volume  of  oxygen.  Of  course 
the  hydrogen,  and  the  oxygen  which  combine  with  it,  will 
be  condensed;  so  that  after  the  explosion,  unless  so  far  as 
absorbed  by  the  water,  two  volumes  of  carbonic  acid  will 
remain  mingled  with  the  one  volume  of  oxygen  in  excess. 

Of  certain  Gaseous  Compounds  formed  by  igniting  the  Gaseous  Elements 
of  Water ',  while  containing  Olefiant  Gas,  or  the  Vapour  of  Ethers,  or 
Essential  Oils. 

1276.  I  observed  some  years  ago,  that  when  olefiant  gas  is  inflamed  with 
an  inadequate  supply  of  oxygen,  carbon  is  deposited,  so  copiously  as  to  ren- 
der the  glass  receiver  of  the  eudiometer  impervious  to  light,  while  the  result- 
ing gas  occupies  double  the  space  of  the  mixture  before  explosion.     Of  this 
I  conceive  I  have  discovered  the  explanation.     By  a  great  number  of  expe- 
riments, performed  with  the  aid  of  my  barometer-gauge  eudiometer,  I  have 
ascertained  that  if  during  the  explosion  of  the  gaseous  elements  of  water 
any  gaseous  or  volatile  inflammable  matter  be  present,  instead  of  condensing 
there  will  be  a  permanent  gas  formed  by  the  union  of  the  nascent  water 
with  the  inflammable  matter.     Thus  two  volumes  of  oxygen,  with  four  of 
hydrogen,  and  one  of  olefiant  gas,  give  six  volumes  of  permanent  gas, 
which  burns  and  smells  like  light  carburetted  hydrogen.     The  same  quan- 
tity of  the  pure  hydrogen  and  oxygen,  with  half  a  volume  of  hydric  ether, 
gives  on  the  average,  the  same  residue.     One  volume  of  the  new  hyponi- 
trous  ether,  under  like  circumstances,  produced  five  volumes  of  gas. 

1277.  An  analogous  product  is  obtained  when  the  same  aqueous  ele- 
ments are  inflamed  in  the  presence  of  an  essential  oil.     With  oil  of  turpen- 
tine a  gas  was  obtained,  weighing,  per  hundred  cubic  inches,  16T5F  grs., 
which  is  nearly  the  gravity  of  light  carburetted  hydrogen.     The  gas  ob- 
tained from  olefiant  gas,  or  from  ether,  weighed  on  the  average,  per  the 


CARBON.  239 

same  bulk,  13^  grs.  The  olcfiant  gas  which  I  used,  weighed  per  hun- 
dred cubic  inches,  only  30-^  grs.  Of  course,  if,  per  se,  expanded  into  six 
volumes,  it  could  have  weighed  only  one-sixth  of  that  weight,  or  little  over 
five  grains  per  hundred  cubic  inches.  There  can,  therefore,  be  no  doubt 
that  the  gas  obtained  by  the  means  in  question  is  chiefly  constituted  of 
water,  or  of  its  elements,  in  the  proportion  in  which  they  exist  in  that  liquid. 
See  table,  page  189,  for  steam. 

1 278.  The  gas  created  in  either  of  the  modes  abovementioned  does  not 
contain  carbonic  acid,  and  when  generated  from  olefiant  gas,  appears  by 
analysis  to  yield  the  same  quantity  of  carbon  and  hydrogen  as  that  gas 
affords  before  expansion. 

1279.  These  facts  point  out  a  source  of  error  in  experiments,  for  ana- 
lyzing gaseous  mixtures  by  ignition  with  oxygen  or  hydrogen,  in  which 
the  consequent  condensation  is  appealed  to  as  a  basis  for  an  estimate.     It 
appears  that  the  resulting  water  may  form  new  products  with  certain  vola- 
tilizable  substances  which  may  be  present. 

1280.  The  gas  obtained  by  passing  the  vapour  of  alcohol  through  an 
ignited  porcelain  tube,  is  confounded  generally  with  that  which  results  from 
the  reaction  of  sulphuric  acid  with  alcohol,  as  above  described,  (1273,)  but 
equal  volumes  of  the  gaseous  products  obtained,  the  two  processes  being 
analyzed,  I  found  that  procured  by  ignition  to  have  only  condensed  half  as 
much  oxygen  as  the  other.     From  the  facts  above  stated,  that  the  presence 
of  water  causes  a  union  between  its  elements,  and  those  of  the  carbon  and 
hydrogen  of  carburets,  whether  in  the  form  of  vapour  or  gas,  it  may  be  in- 
ferred that  the  products  of  the  decomposition  of  alcohol  must  vary  accord- 
ingly as  it  may  be  more  or  less  anhydrous.    The  alcohol  which  I  employed 
was  of  the  specific  gravity  nearly  of  840°:  were  absolute  alcohol  subjected 
to  the  process  in  question,  a  gas  containing  a  larger  proportion  of  carbon 
might  be  obtained.  (619,  1252.) 

Experimental  Illustrations. 

1281.  Cork,  cotton-seed,  caoutchouc,  and  nuts,  intro- 
duced in  small  quantities  into  a  gun-barrel,  of  which  the 
butt-end  has  been  heated  to  a  bright  red-heat.  Brilliant 
jet  of  flame  proceeds  from  the  touch-hole.  Inflammation 
of  the  gas  extricated  by  distillation  from  oil  or  bituminous 
coal,  also  of  olefiant  gas.  Olefiant  gas,  mixed  with  oxygen 
gas,  and  exploded  in  a  sliding-rod  eudiometer.  Residue 
renders  lime-water  milky. 

Of  Gas  Lighting. 

1282.  The  gaseous  compounds  of  carbon  and  hydrogen  have  been  much  applied  to 
the  purpose  of  illumination. 

12d3.  The  gas,  for  this  purpose,  is  obtained  by  the  destructive  distillation  of  bitu- 
minous coal,  oil,  or  resinous  substances,  and  is  received  in  gasometers,  whence  it  is 
distributed  through  pipes  to  the  burners.  (C17,  1252.) 


240 


INORGANIC  CHEMISTRY. 


1284.  One  of  the  greatest  obstacles  to  the  general 
employment  of  gas  lights  as  a  substitute  for  candles 
and  lamps,  is  the  necessity  of  pipes  leading  from  gas- 
ometers to  all  situations  where  the  light  is  wanted. 
The  condensation  of  the  gas  into  strong  metallic  re- 
ceivers, has  been  resorted  to  in  order  to  obviate  this 
difficulty.     This  process  may  be  illustrated  by  means 
of  the  apparatus  described  for  the  impregnation  of 
water  with  carbonic  acid,  being  modified  as  represent- 
ed in  the  adjoining  cut. 

1285.  It  is  only  necessary  to  exchange  the  commu- 
nication with  the  self- regulating  reservoir  of  carbonic 
acid  gas,  for  a  similar  communication  with  a  reservoir 
of  olefiant  gas;  and  the  copper  vessel  being  first  ex- 
hausted of  air,  to  condense  the  gas  into  it.     The  sy- 
phon used  for  the  efflux  of  the  impregnated  water,  is 
replaced  by  a  cock  and  tube,  the  latter  terminating 
in  a  capillary  perforation.     Through  this,  the  gas  may 
be  allowed  to  escape  in  a  proper  quantity  to  produce 
a  gas  light  when  inflamed.     It  has,  however,  always 
appeared  to  me,  that  the  expense  of  condensing  the 
gas,  and  of  procuring  and  transporting  the  receiver, 
would  render  this  method  of  affording  light  disadvan- 
tageous. 

1286.  Latterly,  the  loss  of  gaseous  matter,  by  con- 
densation, has  been  found  so  great  as  to  render  the 
process  unprofitable. 


Of  some  Varieties  of  Carbohydrogen,  and  of  the  Bicarburet  of  Hydro- 
gen. 

1287.  Tetartocarbohydrogen,  hexacarbohydrogen,  and  bicarburet  of  hy- 
drogen were  all  obtained  by  Mr.  Faraday  from  the  liquid  which  is  deposited 
from  oil  gas,  when  condensed  into  vessels  under  great  pressure  for  the  pur- 
poses of  illumination. 

1288.  On  subjecting  the  matter,  deposited  as  above  described,  to  a  very 
gentle  heat,  tetartocarbohydrogen  is  separated  in  the  form  of  a  transparent, 
colourless,  inflammable  gas,  with  a  specific  gravity  of  1.9444.    When  cooled 
to  zero,  it  condenses  into  a  transparent  colourless  liquid  of  the  specific  gra- 
vity of  0.627,  being  the  lightest  liquid  known. 

1289.  When  the  liquid  remaining  after  the  extrication  of  the  tetartocar- 
bohydrogen is  heated,  vapour  is  evolved,  and  the  boiling  point  continually 
rises  until  the  temperature  of  176°  is  attained.     Between  this  temperature 
and  190°,  a  large  portion  distils  in  the  form  of  a  liquid.     When  this  liquid 
is  cooled  to  zero,  it  separates  into  two  compounds,  one  of  which  becomes 
solid,  while  the  other  continues  liquid.     The  liquid  is  the  compound  which 
Dr.  Thomson  calls  hexacarbohydrogen,  though  its  composition  does  not  ap- 
pear to  have  been  well  ascertained.     It  is  inflammable,  soluble  in  alcohol, 
and  boils  at  176°.  •    The  solid  compound  is  the  bicarburet  of  hydrogen.     It 
is  at  ordinary  temperatures  a  colourless,  transparent,  volatile  liquid,  which 
boils  at  186°,  and  has  a  specific  gravity  of  0.85.     At  32°  it  crystallizes, 
and,  when  cooled  to  zero,  acquires  a  consistency  like  that  of  loaf  sugar. 

Of  Naphthaline. 

1290.  Naphthaline  is  obtained  by  subjecting  to  distillation  the  tar  which 
is  formed  during  the  decomposition  of  bituminous  coal.     The  first  products 
are  ammonia  water,  and  the  liquid  called  coal  naphtha;  but  towards  the 
close  of  the  process,  naphthaline  is  obtained. 


CA11BON.  241 

1290-  Naphthaline  is  a  white  crystalline  substance,  with  an  aromatic 
smell,  and  a  pungent  disagreeable  taste. 

1291.  There  are  other  compounds  of  carbon  and   hydrogen, — native 
naphtha  for  instance,  and  oil  of  turpentine.     The  almost  endless  variety  of 
the  essential  oils  derived  from  vegetables,  consist  either  wholly  or  principal- 
ly of  carbon  and  hydrogen.     Of  some  of  these.  I  shall  hereafter  briefly  treat ; 
to  notice  them  all  would  be  inconsistent  with  the  limits  prescribed  to  this 
work. 

Of  the  Compounds  formed  by  Carbon  with  Chlorine  and  Hydrogen. 

1292.  It  has  already  been  stated   that  olefiant  gas  received  its  name 
in  consequence  of  its  being  condensible  with  chlorine  into  a  liquid  of  an 
oleaginous  consistency.     To  this  liquid  the  name  of  chloric  ether  has  been 
improperly  given,  as  it  indicates  a  dependency  on  chloric  acid  for  its  con- 
stitution or  generation,  contrary  to  the  fact.     As  it  consists  of  two  atoms  of 
chlorine  and  one  of  etherine,  a  more  appropriate  name  would  be  bichlorine 
ether. 

1293.  Bichlorine  ether  is  limpid  and  colourless  like  water,  has  a  pleasant 
smell,  and  an  agreeable  sweet  .taste. 

1294.  Chlorine  combines  with  several  other  of  the  polymeric  varieties  of 
carbohydrogen,  forming  with  them  compounds  of  different  properties.     It 
also  produces  two  compounds  by  combining  with  the  bicarburet  of  hydro- 
gen; one  solid,  the  other  liquid. 

COMPOUND  OF  CARBON  WITH  NITROGEN. 
Of  Bicarburet  of  Nitrogen,  or  Cyanogen. 

1295.  Cyanogen  ranks  next  to  iodine  among   electro- 
negative bodies.     It  is  included  among  the  halogen  bodies 
of  Berzelius,  and  in  the  basacigen  class  by  me.  (625,  634.) 
Being  a  compound,  I   have  deferred   treating  of  it  until 
now. 

1296.  Preparation. — Cyanogen  is  obtained  by  subjecting 
pure  and  dry  bicyanide  of  mercury  to  a  low  red-heat  in  a 
porcelain  or  coated  glass  retort  or  tube,  and  receiving  the 
product  over  mercury. 

1297.  Properties. — Cyanogen  is  a  colourless,  transpa- 
rent, irrespirable  gas,  which  painfully  affects  the  nose  and 
eyes,  and  has  a  strong  and  peculiar  odour.     Under  a  pres- 
sure of  four  atmospheres,  it  becomes  a  colourless  liquid, 
lighter  than  water.     It  may  likewise  be  liquefied,  or  even 
solidified  by  cold.     It  is  characterized  by  burning  with  a 
beautiful  violet  flame.     It  is  decomposed  by  the  electric 
spark,  or  by  an  incandescent  iron  into  its  constituents,  car- 
bon and  nitrogen.     Alcohol  dissolves  twenty-three  times, 
and  water  four  and  a  half  times  its  volume  of  cyanogen.    In 
the  course  of  a  few  days  the  solutions  become  discoloured, 
and  a  brown  matter  is  deposited.     The  deposition  from  al- 

31 


242  INORGANIC   CHEMISTRY/. 

cohol  has  been  found  to  contain  carbon  and  nitrogen. 
After  obtaining  cyanogen  from  the  bicyanide  of  mercury, 
a  black  residuum  is  found  in  the  retort,  which  has  been 
conceived  to  consist  of  carbon  with  a  lesser  proportion  of 
nitrogen  than  exists  in  cyanogen;  but  of  late,  this  resi- 
duum, and  the  deposition  from  alcohol,  have  been  supposed 
to  be  isomeric  with  cyanogen. 

1298.  When  ignited  with  two  volumes  of  oxygen,  a  vo- 
lume of  cyanogen  is  converted  into  two  volumes  of  carbo- 
nic acid  and  one  of  nitrogen,  without  condensation.     Of 
course,  as  each  volume  of  carbonic  acid  requires  a  volume 
of  carbon  vapour,  there  must  exist  two  such  volumes  in 
one  of  cyanogen.     Hence,  as  in  the  case  of  carbon  and 
nitrogen  each  volume  represents  an  atom,  cyanogen  con- 
sists of 

two  atoms  of  carbon     =     12 
and  one  of  nitrogen      =     14 

and  its  equivalent  is  26 

Of  the  Nomenclature  of  the  Compounds  of  Cyanogen. 

1299.  When  Prussian  blue  is  digested  with  a  solution  of  potash,  and  the 
resulting  solution  is  filtered  while  hot,  yellow  crystals  are  deposited  by  re- 
frigeration, called  ferroprussiate  or  ferrocyanate  of  potash,  under  the  idea 
that  they  consist  of  an  acid  composed  of  iron,  cyanogen,  and  hydrogen,  in 
union  with  the  oxide  of  potassium.     Berzelius  considers  these  yellow  crys- 
tals as  a  double  salt,  formed  by  a  "  cyanure"  of  iron,  and  a  "  cyanure"  of 
potassium.     The  name  of  this  double  salt,  agreeably  to  his  nomenclature, 
is  "  cyanure  ferroso-potassique."     There  is  another  compound  containing 
the  same  elements,  in  which  the  proportion  of  cyanogen  to  that  in  the  first 
mentioned  compound,  is  as  1$  to  1,  and  for  which  his  name  is  "cyanure 
ferrico-potassique" 

1300.  The  existence  of  these  combinations  constitutes  one  instance  among 
many,  in  which,  according  to  Berzelius,  two  compounds,  each  having  the 
same  halogen  body  as  an  ingredient,  form  by  their  union  a  double  salt. 

1301.  'Agreeably  to  his  system,  we  have  double  "  chlorures,  bromures, 
fluorures"  and  "  iodures"  as  well  as  double  "  cyanures" 

1302.  Some  years  ago,  Bonsdorf,  a  skilful  and  sagacious  German  che- 
mist, assailed  this  classification  of  Berzelius,  by  showing  that  some  of  the 
"  chlorures"  of  the  double  salts  exercised  an  alkaline,  others  an  acid  reac- 
tion, with  vegetable  colouring  matter;  and  that  consequently  the  double 
"  chlorures"  so  called  by  Berzelius,  were  really  simple  salts,  in  which  one 
chlorure  acted  the  part  of  an  acid,  the  other  of  a  base.     Merely  on  con- 
templating the  facts  of  the  case,  as  stated  by  Berzelius,  without  having 
any  knowledge  of  Bonsdorf's  experiments  and  conclusions,  the  conviction 
arose  in  my  mind  that  the  double  haloid  salts,  of  that  great  chemist,  should 
be  considered  as  compounded  of  acids  and  bases.    I  cannot  conceive  where- 
fore Bonsdorf  thought  it  necessary  to  show  that  the  ingredients  of  a  double 
chlorure  should  be  capable  of  reacting  with  vegetable  colouring  matter,  as  if 


CARBON.  243 

one  of  them  were  an  acid,  the  other  a  base,  in  order  to  prove  their  preten- 
sions severally,  to  acidity  and  basidity.-  (629.)  It  appears  to  me,  that, 
excepting  in  the  case  of  the  alkalies  and  alkaline  earths,  those  properties 
have  not  been  deemed  essential  to  oxacids  and  oxibases,  and  that  of  course 
they  ought  not  to  be  required  in  acids  or  bases  formed  by  any  other  of  the 
basacigen  class.  Agreeably  to  the  definition  of  acids  and  bases,  on  which 
the  basacigen  classification  is  founded,  (625  to  632,)  the  "  cyanure"  of  iron 
being  electro-negative  as  .contrasted  with  the  "  cyanure"  of  potassium,  the 
one  must  be  deemed  a  cyanobase,  the  other  a  cyanacid. 

1303.  It  has  been  mentioned  that  by  the  British  and  French  chemists  the 
termination  in  ide  was  made  to  indicate  a  compound  formed  by  a  supporter 
of  combustion  with  a  combustible  or  radical,  while  the  termination  in  uret 
or  ures  was  employed  to  designate  a  compound  formed  of  two  radicals. 
The  difference  in  the  practice  of  the  two  schools  arose  from  the  extension 
of  the  class  of  supporters  by  the  chemists  of  Great  Britain  to  the  simple 
halogen  elements  of  Berzelius,  while,  according  to  those  of  France,  oxygen 
was  the  only  supporter,  all  the  other  elements  being  combustibles  or  radi- 
cals. (685,  &c.)   Hence,  according  to  the  latter,  only  the  compounds  formed 
by  oxygen  have  been  distinguished  by  the  termination  in  ide  as  in  oxide; 
while,  according  to  the  former,  in  addition  to  those  formed  with  oxygen,  we 
have  such  as  are  formed  by  chlorine,  bromine,  iodine,  and  fluorine,  distin- 
guished by  the  termination  in  ide,  as  has  been  already,  to  a  certain  extent, 
explained.  (685.) 

1304.  By  Berzelius  the  termination  in  ide  is  only  resorted  to  where  the 
radical  is  an  electro-negative  body;  or,  in  other  words,  a  body  of  which 
the  oxides  go  to  the  positive  pole.     When  the  radical  is  one  of  those  bo- 
dies which,  when  oxydized,  go  to  the  negative  pole,  the  termination  in  ure  is 
resorted  to.     I  object  to  this  complicated  nomenclature,  as  founded  on  the 
error  of  not  allowing  those  characteristics  of  acids  and  bases  which  have 
been  acted  upon  by  chemists  in  general,  and  by  Berzelius  himself  in  the 
case  of  oxacids  and  oxibases,  to  extend  to  the  binary  compounds  formed  by 
the  bodies  of  the  halogen  class. 

1305.  I  consider  the  yellow  salt  in  question,  as  consisting  of  a  cyanacid 
containing  an  atom  of  cyanogen  and  an  atom  of  iron,  and  which  I  would 
call  cyanoferrous  acid,  united  to  a  cyanobase  of  potassium,  consisting  of 
one  atom  of  cyanogen,  and  one  atom  of  potassium,  and  forming  a  cyano- 
ferrite  of  potassium.     The  double  salt,  consisting  of  the  same  elements, 

but  containing  both  in  the  acid  and  base,  half  an  atom  more  of  cyanogen, 
should,  by  analogy  with  the  oxacids,  have  its  acid  distinguished  by  the 
name  of  cyanoferric  acid,  and  should  itself  be  called  cyanoferrate  of  po- 
tassium. 

Of  Cyanic,  Cyanuric,  and  Fulminic  Acids. 

1306.  An  atom  of  cyanogen,  combined  with  an  atom  of  oxygen,  forms 
cyanic  acid,  which  may  be  obtained  in  union  with  potash,  by  igniting 
peroxide  of  manganese  with  ferroprussiate  of  potash,  or  cyanoferrite  of 
potassium;  being  the  salt  alluded  to  above,  as  consisting  of  cyanogen,  iron, 
and  potassium.     The  cyanogen  and  potassium  are  converted,  by  the  excess 
of  oxygen  in  the  manganese,  into  cyanic  acid  and  potash,  which  unite, 
forming  a  cyanate  of  potash.     Cyanic  acid  cannot,  however,  be  obtained 
from  the  cyanates,  in  consequence  of  its  extreme  susceptibility  of  decom- 
position. 

1307.  A  crystalline  substance  may  be  procured  from  human  urine,  which 


244  INORGANIC  CHEMISTRY. 

is  known  by  the  name  of  urea.  It  consists  of  carbon,  nitrogen,  oxygen, 
and  hydrogen,  in  the  proportion  to  form  one  atom  of  cyanic  acid,  one  atom 
of  ammonia,  and  one  atom  of  water.  When  urea  is  subjected  to  heat, 
ammonia  escapes,  and  an  acid  remains,  which  was  supposed  to  consist  of 
one  atom  of  cyanogen,  and  two  atoms  of  oxygen.  But  it  has  been  recently 
ascertained  by  Wohler  and  Liebig,  that  it  consists  of  the  elements  of  cyanic 
acid,  chemically  united  to  the  elements' of  water;  an  atom  of  hydrogen, 
and  an  additional  atom  of  oxygen,  entering  into  its  composition,  not  as 
water,  but  as  essential  constituents.  Under  these  impressions,  a  new  name, 
cyanuric,  was  given  to  it.  This  acid  is  solid,  fixed,  inodorous,  and  nearly 
tasteless.  By  combining  with  two  atoms  of  water,  as  water  of  crystalliza- 
tion, it  becomes  capable  of  forming  large  crystals. 

1308.  When  anhydrous  cyanuric  acid  is  exposed,  in  a  glass  retort,  to  a 
low  red-heat,  the  extricated  vapours  being  collected  in  a  receiver  refrigerated 
by  a  freezing  mixture,  hydrous  cyanic  acid  is  obtained.     This  acid  and 
cyanuric  acid  consist  of  the  same  elements  in  the  same  proportion,  but 
possess  different  properties  and  atomic  weights.     Hydrous  cyanic  acid  is  a 
colourless,  volatile  liquid,  possessing  a  penetrating  odour  resembling  that 
of  acetic  acid.     It  vesicates  the  skin  when  applied  to  it,  exciting  intense 
pain.     Its  vapour  reddens  litmus  paper,  is  inflammable,  and  so  pungent  as 
to  produce  tears,  and  cause  severe  pain  in  the  hands.     Cyanuric  acid  is 
comparatively  inert  in  these  respects,  but  is  far  less  susceptible  of  decom- 
position; as  it  is  not  decomposed  by  solution  in  boiling  nitric  or  sulphuric- 
acid,  while  hydrous  cyanic  acid  is  decomposed  by  the  addition  of  water, 

1309.  Hydrous  cyanic  acid,  at  the  ordinary  temperature  of  the  air,  spon- 
taneously undergoes  an  explosive  decomposition,  attended  by  an  evolution 
of  heat,  and  is  converted  into  a  solid  mass  of  dazzling  whiteness.     This 
mass  consists  of  a  variety  of  cyanuric  acid,  which  differs  from  that  above 
described,  in  being  insoluble  in  water  or  nitric  acid,  and  in  being  decom- 
posed by  sulphuric  acid.     It  is,  therefore,  to  be  considered  as  presenting  a 
case  of  isomerism.   (1153). 

1310.  It  is  remarkable  that,  although  cyanuric  acid  consists  of  the  same 
elements  in  the  same  proportion  as  hydrous  cyanic  acid,  it  carries  the  hy- 
drogen and  oxygen  which  exist  in  it  in  the  proportion  to  form  water,  into 
every  combination  which  it  forms ;  while  the  hydrous  cyanic  acid,  in  com- 
bining with  bases,  separates  from  the  water,  which  must  be  considered, 
when  in  union  with  this  acid,  as  acting  as  a  base. 

1311.  To  bodies  which,  although  they  contain  the  same  elements  in  the 
same  ratio,  yet  hold  them  differently  associated,  so  that  in  reacting  with 
other  agents,  they  are  resolved  into,  or  form  compounds  differing  in  com- 
position, the  term  metameric  has  been  applied.     Thus  hydrous  cyanic,  and 
cyanuric  acid  are  said  to  be  metameric  with  regard  to  each  other. 

1312.  Another  compound  of  cyanogen  with  oxygen  exists  in  the  fulmi- 
nating mercury  of  Howard,  and  the  analogous  fulminating  silver  of  Desco- 
tils.     Liebig  ascertained  these  compounds  to  contain  an  acid  common  to 
both,  which  he  called  fulminic  acid,  but  which,  agreeably  to  the  analysis 
made  by  him  and  Gay  Lussac,  was  identified  in  composition  with  cyanic 
acid.     Yet,  as  the  latter  would  not  produce  fulminating  compounds,  and 
differed  in  its  other  properties,  these  acids  have  been  considered  as  afford- 
ing another  instance  of  isomerism.     Mr.  Edmund  Davy,  however,  alleges- 
the  existence  of  hydrogen  in  fulminic  acid,  and  likewise  that  the  nitrogen 
exists  in  excess,  beyond  the  proportion  appropriate  to  cyanogen. 

1313.  Fulminic  acid  is  a  colourless,  transparent,  volatile  liquid,  which 


CARBON.  245 

reddens  litmus,  and  produces  a  taste  at  first  sweet,  but  afterwards  astringent 
and  disagreeable.  Its  fumes  have  a  pungent  and  disagreeable  odour,  and 
produce  headach  when  incautiously  inhaled. 

1814.  Besides  these  acids,  M.  Liebig  has  recently  discovered  another, 
which  is  polymeric  with  regard  to  cyanUric  acid;  as  it  consists  of  the  same 
elements  in  the  same  ratio,  though  twice  as  much  of  each  enters  into  the 
composition  of  an  atom. 

Of  the  Chlorides,  Bromides,  and  Iodides  of  Cyanogen. 

1315.  Chlorine  forms  two  compounds  with  cyanogen,  a  protochloride 
and  a  perchloride.    The  protochloride  is  a  colourless,  fetid  gas,  which  may 
be  liquefied,  and  even  solidified  by  cold.     In  common  with  several  other 
compounds  of  cyanogen,  it  possesses,  even  when  gaseous,  the  singular  pro- 
perty of  producing  pain  by  contact  with  the  skin.     The  perchloride  is  a 
white  crystalline  substance,  with  an  odour  resembling  that  of  mice. 

1316.  Bromine  and  iodine  both  form  with  cyanogen,  crystalline  com- 
pounds.    The  chlorides  and  bromides  of  cyanogen  are  energetic  poisons. 

Of  Sulphocyanogen. 

1317.  It  has  been  stated  that  the  yellow  salt,  usually  known  as  ferro- 
prussiate  of  potash,  is  by  Berzelius  considered,  when  free  from  water,  as 
consisting  of  cyanogen,  iron,  and  potassium ;  also  that  I  consider  it  as  a 
cyanoferrite  of  the  cyanobase  of  potassium.    When  this  salt,  desiccated  to 
efflorescence  and  finely  pulverized,  is  mingled  with  flowers  of  sulphur,  and 
exposed  to  a  red-heat  in  a  porcelain  crucible,  the  iron  is  displaced;  the  sul- 
phur and  cyanogen  uniting,  form  a  compound  called  sulphocyanogen,  and 
this  uniting  with  the  potassium,  constitutes  a  sulphocyanide.  (1302.) 

1318.  Sulphocyanogen  has  been  isolated  by  passing  chlorine  through  a 
solution  of  sulphocyanide  of  potassium,  or  by  subjecting  that  compound  to 
nitric  acid.     Sulphocyanogen  has  some  pretensions  to  be  classed  with  the 
halogen,  and  of  course  with  the  basacigen  bodies. 

1319.  The  intense  blood-red  colour  which  it  produces  with  iron,  is  the 
most  striking  property  of  sulphocyanogen,  and  has  led  to  the  impression 
that  the  sulphocyanide  of  iron  may  be  the  colouring  matter  of  the  blood. 

1320.  Sulphocyanogen  is  solid,  insoluble  in  water  or  alcohol,  and  may, 
in  its  anhydrous  state,  be  sublimed  without  change.     It  is  composed  of  one 
atom  of  cyanogen,  and  two  atoms  of  sulphur. 

1321.  Dr.  Thomson  states  that  another  compound  of  sulphur  and  cyano- 
gen exists,  containing  one  atom  of  sulphur  and  two  atoms  of  cyanogen. 
This  compound  may  be  obtained  in  transparent  colourless  crystals.     It  is 
volatile,  possesses  a  strong  smell,  and  is  soluble  in  water.     When  applied 
to  the  tongue,  even  in  a  minute  quantity,  it  produces  intense  pain;  and  the 
part  touched  remains  red  and  painful  for  some  time. 

Of  Sulphocyanhydric  Acid. 

1322.  This  acid  may  be  obtained  from  a  solution  of  the  sulphocyanide 
of  potassium,  by  the  addition  of  phosphoric  acid.     Water  is  decomposed, 
the  oxygen  unites  with  the  potassium,  forming  potash,  with  which  the  phos- 
phoric acid  combines,  and  the  hydrogen  with  the  sulphocyanogen,  formino; 
sulphocyanhydric  acid,  which  may  be  separated  by  distillation.     This  acid 
is  liquid  and  colourless,  has  an  acid  taste,  and  powerful  odour.    It  becomes 


246  INORGANIC  CHEMISTRY. 

solid  at  14°,  and  boils  at  216°.     It  is  composed  of  one  atom  of  sulpho- 
cyanogen,  and  one  atom  of  hydrogen. 

Of  Cyanhydric  or  Prussic  Acid. 

1323.  One  atom  of  cyanogen,  equivalent  26,  with  one 
atom  of  hydrogen,  equivalent  1,  forms  one  atom  of  cyan- 
hydric  acid,  equivalent  27. 

1324.  This  acid  has  been  detected  in  water  distilled 
from  bitter  almonds  and  from  laurel  leaves,  also,  from 
peach  leaves  or  blossoms.     Between  the  odour  of  these, 
and  that  of  the  acid  when  dilute,  it  would  be  difficult  to 
discriminate. 

1325.  Laurel  water  has  long  been  known  as  a  poison. 
Water  distilled  from  peach  leaves  has  been  used  to  impart 
an  agreeable  flavour  to  food.     Some  peach  leaf  water, 
prepared  by  Mr.  Wetherill,  gave  indications  of  cyanhydric 
acid,  by  producing  a  blue  colour  with  a  solution  of  iron. 

1326.  There  have  been  instances  in  which  noyeau,  a 
cordial  made   from  the   kernels  of  bitter   almonds,  has 
proved  poisonous  from  the  presence  of  cyanhydric  acid. 

1327.  There  is  a  salt  consisting  of  two  atoms  of  cyano- 
gen  and   one  of  mercury,  called  bicyanide  of  mercury. 
When  this  salt  is  subjected  to  the  action  of  chlorohydric 
acid,  the  chlorine  forms  a  chloride  with  the  mercury,  while 
the  hydrogen  forms  cyanhydric  acid  with  the  cyanogen. 

1328.  It  may  be  more  conveniently  obtained  by  impreg- 
nating with  sulphydric  acid,  a  solution  containing  sixty 
grains  of  bicyanide  of  mercury  for  every  ounce  of  water. 
The  hydrogen  unites  with  the  cyanogen,  while  the  sulphur 
precipitates  with  the  metal.     Any  excess  of  the  sulphydric 
acid  is  easily  removed  by  the  carbonate  of  lead.     The 
apparatus  for  impregnation  with  sulphydric  acid,  has  been 
described  already.  (797-8.) 

1329.  The  acid  may  be  procured  in  its  most  concen- 
trated form,  by  exposing  the  bicyanide  in  crystals,  in  a 
tube,  to  sulphydric  acid  gas,  and  employing  a  receiver, 
surrounded  by  salt  and  snow,  to  condense  the  vapour 
evolved. 

1330.  In  performing  this  process,  I  found  great  difficulty 
to  arise  from  the  inability  of  the  operator  to  regulate  the 
quantity  of  gas  introduced  into  the  tube,  so  that,  on  the 
one  hand,  there  might  be  no  absorption  of  atmospheric 
air,  and,  on  the  other,  no  excess  of  the  gas  escaping,  and 


CARBON. 


247 


consequently  causing  a  loss  of  materials,  and  annoyance 
to  the  bystanders.  This  difficulty  is  in  great  measure  re- 
moved, by  means  of  the  apparatus  of  which  an  engraving 
and  description  is  subjoined. 

Apparatus  for  the  Evolution  of  Cyanhtjdric  or  Prussic  Acid. 


1331.  Let  a  tube,  three-fourths  of  an  inch  in  bore  and  about  two  feet  in  length,  be 
bent  at  right  angles,  at  about  six  inches  distance  from  one  end.     Let  the  shorter 
portion  be  drawn  out  into  a  tapering  form,  with  a  bore  not  exceeding  a  tenth  of  an 
inch  in  diameter.     Upon  the  larger  orifice  let  a  brass  band  be  cemented,  in  which  a 
female  screw  has  been  cut,  so  that  a  stuffing-box,  furnished  with  a  corresponding 
male  screw,  may  be  easily  fastened  air-tight  to  the  band,  or  removed  when  desirable. 
Through  the  stuffing-box  an  iron  rod  passes,  flattened  like  an  oar  at  the  end,  which 
is  within  the  tube  when  the  stuffing-box  is  in  its  place.     There  must  likewise  be  a 
lateral  aperture  in  the  band  communicating  with  the  cavity  of  the  tube,  and  fur- 
nished with  a  gallows  screw.     The  main  body  of  the  tube  is  to  be  situated  nearly 
level,  yet  a  little  inclined  towards  the  curvature,  so  that  the  tapering  extremity  may 
descend  nearly  perpendicularly  into  a  tall  narrow  phial,  surrounded  by  a  freezing 
mixture.     The  horizontal  portion  of  the  tube  near  the  bend  should  likewise  be  re- 
frigerated.    The  apparatus  being  thus  arranged,  introduce  a  sufficient  quantity  of 
the  by  cyanide  of  mercury  into  the  tube,  and  close  it  by  inserting  the  stuffing-box 
with  its  rod.     In  the  next  place,  by  means  of  the  gallows  screw,  make  a  communi- 
cation between  the  cavity  of  the  tube,  and  a  self-regulating  reservoir  of  sulphydric 
acid.     This  gas  must  be  allowed  to  pass  into  the  tube  very  slowly,  and  meanwhile, 
by  means  of  the  rod,  the  bicyanide  is  to  be  stirred.     Before  long  a  portion  of  the  cy- 
anhydric  acid  will  be  seen  in  the  narrow  part  of  the  tube.     This  serves  to  regulate 
the  admission  of  the  sulphydric  acid,  since,  when  the  quantity  passing  into  the  tube 
is  inadequate,  the  liquid  will  rise  in  the  tube;   when  too  great,  it  will  be  expelled 
from  it.     By  these  means,  after  a  little  while,  all  the  bicyanide  will  be  decomposed, 
and  a  corresponding  quantity  of  acid  collected  in  the  refrigerated  phial. 

1332.  Since  this  figure  was  engraved,  I  have  found  it  preferable  to  have  a  phial 
made  with  a  bottom  tapering  to  a  point,  so  that  the  quantity  of  acid,  however  minute, 
becomes  apparent;  and  it  is  sooner  rendered  competent 'to  act  as  an  index  of  the  pro- 
gress of  the  process;  so  as  to  regulate  the  quantity  of  gas  to  be  allowed  to  enter  the 
tube.    It  has  also  been  found  advantageous  to  mix  the  bicyanide  intimately  with 
about  twice  its  bulk  of  glass,  powdered  to  the  consistency  of  coarse  sand. 

New  Process  for  Liquid  Cyarihydric  Acid. 

1333.  The  following  process  for  procuring  prussic  acid,  is  recommended 
by  Professor  Everitt.* 

1334.  For  every  212  grains  of  ferroprussiate  of  potash  (cyanoferrite  of 
potassium,)  in  2  ounces  of  water  introduced  into  a  retort,  add  as  much  sul- 

*  London  and  Edinburg  Philosophical  Magazine,  vol.  6,  p.  100. 


248  INORGANIC  CHEMISTRY. 

phuric  acid  as  may  be  equivalent  to  120  grains  of  the  anhydrous  acid;  and 
distilling  the  mixture,  let  the  vapour  pass  into  a  pint  of  refrigerated  water, 
holding  255  grains  of  nitrate  of  silver.  The  resulting  precipitate  being 
washed  and  dried,  should  constitute  nearly  201  grains  of  mercurial  cyanide. 
Of  this  let  40  grains  be  introduced  into  7  fluid  ounces,  and  20  minims  of 
water;  and  add  40  minims  of  chlorohydric  acid,  of  specific  gravity  of  1.129. 
The  whole  being  well  secured  in  a  stoppered  bottle,  and  agitated  repeatedly, 
should  be  allowed  to  rest  until  the  resulting  chloride  of  silver  subsides.  In 
the  solution  thus  obtained,  when  carefully  decanted,  there  will  be-  one  grain 
of  prussic  acid  (more  properly  called'  cyanhydric  acid,)  for  every  fluid 
ounce  of  water. 

1335.  Should  there  be  a  little  excess  of  chlorohydric  acid,  agreeably  to 
Professor  Everitt's  observation,  confirmed  by  those  of  others,  it  will  tend 
rather  to  preserve,  than  to  decompose  the  acid. 

1336.  Properties  of  Cyanhydric  Acid. — This  acid  is  a 
colourless  liquid,  which  emits  a  powerful  odour,  resembling 
that  of  peach  blossoms.     When  perfectly  free  from  water, 
it  is  far  more  volatile  than  ether,  as  it  boils  at  79°  F.,  and 
evaporates  so  rapidly,  that  one  portion  becomes  frozen  by 
the  loss  of  the  caloric  which  the  other  absorbs  in  passing 
into  the  aeriform  state.     Its  specific  gravity  is  0.7058,  be- 
ing nearly  the  same  as  that  of  sulphuric  ether. 

1337.  Anhydrous  cyanhydric  acid  is  sometimes  decom- 
posed in  a  few  hours,  especially  if  not  protected  from  the 
light,  and  can  never  be  preserved  longer  than  a  fortnight. 
Either  when  in  the  state  of  a  liquid,  or  vapour,  this  acid 
is  probably  the  most  active  poison  known.     The  applica- 
tion of  a  few  drops  to  the  arm  of  a  man  has  produced 
death,  and  its  fumes  are  equally  deleterious  when  inspired. 
As  when  free  from  water,  this  acid  boils  at  79°,  nearly  20° 
below  the  temperature  of  the  blood,  it  must  be  converted 
into  vapour  too  soon  to  produce  its  full  effect.     From  a 
cavity  like  the  ear,  the  pure  acid  must  be  ejected  in  vapour 
immediately.     I  am,  therefore,  under  the  impression  that 
it  is  less  effectual  as  a  poison  when  anhydrous,  than  when 
combined  with  a  minute  proportion  of  water. 

1338.  Upon  one  occasion,  touching  the  ear  of  a  rat  con- 
fined in  a  glass  jar  with  a  drop  of  the  anhydrous  acid,  the 
animal,  being  obliged  to  breathe  the  vapour,  died  instanta- 
neously with  a  slight  sneezing.     Yet  upon  another  occa- 
sion nearly  half  a  drachm  was  injected  into  the  ear  of  a 
large  dog,  without  causing  death;  a  like  quantity,  subse- 
quently injected  into  his  nose,  proved  fatal.    The  acid  em- 
ployed was  so  pure  as  to  freeze  by  its  own  evaporation. 


HURON.  249 

1339.  The  best  antidotes  for  this  poison  are  chlorine  or 
ammonia,  in  dilute  aqueous  solution,  especially  chlorine. 

1340.  Cyanhydric  acid  is  sometimes  employed  in  medi- 
cine, though  in  very  small  doses,  and  in  a  very  diluted 
state. 

1341.  It  has  been  proposed  to  detect  cyanhydric  acid, 
in  cases  in  which  it  may  have  been  employed  in  poisoning, 
by  subjecting  the  stomach  and  its  contents  to  distillation 
with  water,  and  testing  the  liquid  product  by  copper  or 
iron. 

1342.  I  should  place  much  reliance  on  the  characteristic 
smell  of  the  acid,  which  is  that  of  peach  blossoms,  and 
which  may  be  perceived,  not  only  from  the  presence  of 
the  acid,  but  likewise  from  that  of  any  of  the  cyanides,  if 
subjected  to  the  action  of  chlorohydric  acid. 

Experimental  Illustrations. 

1343.  The  processes  for  the   production  both  of  the 
aqueous  and  anhydrous  cyanhydric  acid,  exhibited;  also, 
the  congelation  of  the  latter  by  the  cold  arising  from  its 
own  evaporation. 


SECTION    V. 

OF  BORON. 

1344.  Preparation. — By  the  addition  of  sulphuric  acid 
to  a  saturated  solution  of  biborate  of  soda  (borax)  in  wa- 
ter, shining  crystalline  plates  are  precipitated,  consisting  of 
boric  acid.     From  these  crystals  boron  may  be  obtained, 
either  by  the  action  of  a  powerful  Voltaic  series,  or  by 
first  vitrifying  them,  then  finely  pulverizing  the  resulting 
glass,  and  afterwards  heating  the  acid  thus  prepared   in 
contact  with  potassium. 

1345.  Boron  may  be  obtained  by  means  of  the  appa- 
ratus employed  for  the  evolution  of  silicon,  (1355,  &c. 
1357,  &c.)  substituting  fluoboric  acid  gas  for  fluosilicic 
acid  gas. 

1346.  Properties. — Boron  is  of  a  dark  olive  colour,  taste- 
less, inodorous,  a  non-conductor  of  electricity,  and  insolu- 
ble either  in  alcohol,  ether,  or  the  oils.     Its  atomic  weight 

32 


250  INORGANIC  CHEMISTRY. 

is  11.  It  is  susceptible  neither  effusion  nor  volatilization. 
When  heated  in  the  air  to  600°  F,  it  takes  fire,  and,  by 
uniting  with  oxygen,  generates  boric  acid.  Nevertheless 
only  a  portion  of  the  boron  is  oxydized,  the  remainder 
being  protected  by  a  crust  of  fused  boric  acid.  If  this 
crust  be  removed  by  water,  the  boron  will  be  found  to 
have  undergone  a  change  similar  to  that  produced  in  char- 
coal by  an  intensely  high  temperature.  It  is  rendered 
harder,  more  difficult  to  ignite,  and  so  much  denser,  that, 
although  its  specific  gravity  was  before  only  1.83,  it  now 
sinks  rapidly  in  sulphuric  acid  of  the  specific  gravity  of 
1.844.  Before  it  has  been  ignited,  boron  is  slightly  solu- 
ble in  water;  and  its  solution,  when  evaporated  to  a  cer- 
tain point,  forms  a  gelatinous  mass,  which,  by  complete 
desiccation,  becomes  opaque,  and  assumes  the  usual  ap- 
pearance of  boron. 

COMPOUND  OF  BORON  WITH  OXYGEN. 
Of  Boric*  or  Boracic  Acid. 

1347.  The  means  of  procuring  this  acid  have  been  men- 
tioned in  describing  the  process  for  obtaining  boron.     Bo- 
rax is  a  biborate  of  soda,  from  which  boric  acid  may  be 
liberated  in  crystals,  as  above  described,  by  the  superior 
affinity  of  sulphuric  acid  for  the  soda. 

1348.  Properties. — Boric  acid  is  crystalline  as  first  ob- 
tained from  borax,  but  forms  a  glass  when  deprived  by 
heat  of  its  water  of  crystallization.     It  is  colourless,  in- 
odorous, almost  tasteless,  and  sparingly  soluble  in  water. 
In  the  form  of  an  aqueous  solution,  its  agency  is  weak, 
and  it  is  in  consequence  rarely  used  in  that  state.     In  com- 
mon with  silicic,  phosphoric,  and  arsenic  acid,  being  fixed 
at  temperatures  at  which  sulphuric  and  nitric  acid  are  de- 
composed, it  will  at  those  heats  expel    them  from  their 
combinations;   although,  when  water  is   present,  and   at 
low  temperatures, ,  it   is  displaced   from  combination  not 
only  by  those  acids,  but  by  many  others.     It  consists  of 
one  atom  of  boron,  and  three  of  oxygen. 

1349.  Boron,  in    its   habitudes,  seems  to   lie   between 
phosphorus  and  carbon.     In  its  insusceptibility  of  volatili- 

*  I  agree  with  the  French  chemists  and  Berzelius,  in  employing  the  word  boric 
instead  of  Loracic,  as  more  naturally  generated  from  boron,  by  analogy  with  the  other 
acids  formed  with  radicals,  to  the  last  letter  of  which  the  letters  ic  are  usually  added. 


Apparatus  for  the  Evolution  of  Silicon. 
A 


(Page  251.) 


SILICON.  251 

zation,  infusibility,  and  the  temperature  requisite  for  its 
combustion,  it  is  most  allied  to  carbon;  yet  boric  acid  is 
more  analogous  to  phosphoric  than  to  carbonic  acid. 
Both  phosphoric  and  boric  acid  are  capable  of  being  re- 
duced to  a  vitreous  state,  and  bear  a  white-heat  without 
being  volatilized;  while  the  acid  of  carbon  is  naturally 
aeriform. 

1350.  Boric  acid  and  the  biborate  of  soda  are  of  great 
use  in  blowpipe  assays,  as  fluxes,  and  in  soldering,  as  the 
means  of  protecting  metallic  surfaces  from  oxidation. 

Experimental  Illustrations. 

1351.  Saturated  solution  of  borax,  decomposed  by  sul- 
phuric acid.     Exhibition  of  crystals  of  the  acid  and  of  the 
biborate,  which  are  severally  fused  into  a   glass  by  the 
compound   blowpipe.     Effects   of  cobalt  and  manganese 
upon  the  colour  of  the  glass,  of  which  a  globule  is  conve- 
niently supported  by  a  platinum  wire. 

Of  Chloride  of  Boron. 

1352.  The  chloride  of  boron  maybe  obtained  by  the  combustion  of  boron 
in  chlorine  ;  or  by  passing  a  current  of  chlorine  over  a  mixture  of  charcoal 
and  boric  acid,  heated  to  redness  in  a  porcelain  tube. 

1353.  The  chloride  of  boron  is  a  colourless  gas,  possessing  a  strong  and 
peculiar  smell.     When  brought  in  contact  with  water,  a  reciprocal  decom- 
position takes  place,  and  boric  and  chlorohydric  acid  result.     It  forms  a 
white  salt  with  ammonia,  and  is  by  some  chemists  considered  as  an  acid. 


VI. 

OF  SILICON. 

1354.  Preparation.  —  By  heating  sulphuric  acid  with  a 
mixture  of  powdered  Derbyshire  spar,  and  powdered  glass* 
or  quartz,  a  permanent  gas  may  be  obtained.  When  po- 
tassium is  heated  in  this  gas,  silicon  is  evolved. 

Apparatus  for  evolving  Silicon  from  Fluosilidc  Add,  Gas  by  means  of  Potassium. 

1355.  This  apparatus  is  represented  by  the  opposite  engraving.  Into  a  stout  ma- 
hogany block  as  a  basis,  two  iron  rods,  A  A,  are  so  planted  as  to  extend  perpendicu- 
larly, and  of  course  parallel  to  each  other,  about  two  feet  in  height.  Upon  these 
rods  two  iron  bars  are  supported  horizontally,  one  B,  near  their  upper  extremities, 
the  other,  at  the  height  of  about  six  inches  from  the  wooden  basis.  In  the  centre  of 
the  lower  bar,  there  is  a  screw,  D,  having  a  handle  below  the  bar,  and  supporting 
above  it  a  circular  wooden  block.  Into  a  hole  in  the  upper  iron  bar,  equidistant  from 
the  rods,  is  inserted  a  hollow  brass  cylinder,  C,  which  at  the  lower  end  screws  into 


252  INORGANIC  CHEMISTRY. 

an  aperture  in  a  circular  plate  of  brass,  E,  which  is  thus  supported  horizontally  a 
few  inches  below  the  bar.  By  these  means,  room  is  allowed  for  the  insertion  into 
the  cylinder  of  four  valve  cocks,  each  furnished  with  a  gallows  screw.  The  cylinder 
is  surmounted  by  a  stuffing-box,  F,  through  which  a  copper  sliding-rod,  G,  passes 
air-tight.  The  brass  plate  is  turned  and  ground  to  fit  a  bell  glass  of  about  five  inches 
in  diameter,  and  eight  inches  in  height,  which  is  pressed  up  when  necessary  between 
the  plate  and  the  block,  by  the  screw,  D,  supporting  the  block.  Within  the  space 
comprised  by  the  bell  glass,  and  on  one  side  of  the  centre  of  the  plate,  two  stout 
brass  wires  are  inserted,  one  of  them  insulated  by  a  collar  of  leathers,  so  as  to  admit 
of  the  ignition,  by  a  galvanic  discharge,  of  a  small  arch  of  platinum  wire,  which 
reaches  from  one  to  the  other.  The  sliding-rod  abovementioned  as  occupying  the 
stuffing-box,  terminates  below  the  plate  in  an  elbow  which  supports  a  cup  at  right 
angles  to  the  rod,  at  the  same  distance  from  the  rod  as  the  platinum  wire;  and  on 
the  opposite  side  of  it,  there  is  a  brass  cover,  H,  for  the  cup,  supported  from  the 
plate.  The  arrangement  is  such,  that  by  a  suitable  movement  in  the  sliding-rod, 
made  by  grasping  it  by  the  handle,  G,  in  which  it  terminates  externally,  the  cup 
may  be  made  either  to  receive  into  its  cavity  the  platinum  wire,  or  to  adjust  itself  to 
its  cover,  H. 

1356.  The  bell  being  removed,  about  sixty  grains  of  potassium,  in  pieces  not  con- 
taining more  than  fifteen  grains  each,  are  to  be  introduced  into  the  cup,  which  is 
then  to  be  adjusted  to  the  cover,  and  the  beli  secured.  In  the  next  place,  by  means 
of  the  flexible  lead  tubes,  P,  P,  P,  P,  and  the  gallows  screws  attached  to  the  valve 
cocks,  established  a  communication  severally  with  an  air  pump,  a  self- regulating 
reservoir  of  hydrogen,  a  barometer  gauge,  and  ajar  over  the  mercurial  cistern,  con- 
taining fluosilicic  acid  gas.  First,  by  means  of  the  air  pump,  exhaust  the  bell,  and, 
in  order  to  wash  out  all  remains  of  atmospheric  air,  admit  hydrogen  from  the  reser- 
voir. Again  exhaust,  and  again  admit  hydrogen.  Lastly,  exhaust  the  bell  of  hydro- 
gen, and  admit  the  fluosilicic  acid  gas.  By  means  of  the  gauge,  the  exhaustion  is 
indicated  and  measured,  and  by  the  same  means  it  will  be  seen  when  the  pressure  of 
the  gas  within  the  bell  approaches  that  of  the  atmosphere.  When  this  takes  place, 
the  cocks  being  all  closed,  and  by  means  of  the  process  of  galvano-ignition,  (335, 
&c.)  the  platinum  wire  being  rendered  incandescent,  the  potassium  is  to  be  brought 
into  contact  with  it.  A  peculiar  deep  red  combustion  ensues,  evolving  copiously 
chocolate-coloured  fumes,  which  condensing  into  flocks  of  the  same  hue,  descend 
throughout  the  receiver,  and  are  deposited  upon  the  interior  surface,  so  as  to  create 
in  the  mind  of  the  spectator,  the  idea  of  a  miniature  fall  of  chocolate-coloured  snow. 
On  removing  the  bell  after  the  potassium  has  ceased  to  burn,  the  cup  which  held  it 
is  found  to  contain  silicon  mixed  with  the  fluoride  of  potassium,  and  with  this  the 
whole  of  the  chocolate-coloured  deposition  is  contaminated.  Siliciuret  of  potassium 
is  likewise  found  in  the  cup  ;  since,  upon  the  affusion  of  water,  a  fetid  inflammable 
gas  is  evolved,  which  has  an  odour  resembling  that  of  phosphoretted  hydrogen,  and 
which  must  obviously  be  the  analogous  compound  siliciuretted  hydrogen.  The  sili- 
con, being  insoluble,  may  be  separated  from  the  fluoride  by  digestion  in  water.  When 
the  potassium  employed  is  of  the  kind  obtained  by  means  of  charcoal,  the  silicon  is, 
as  Berzelius  alleges,  adulterated  with  carbon.  I  am  under  the  impression  that  strong 
nitric  acid  removes  this  impurity. 

Simple  Process  for  the  Evolution  of  Silicon. 

1357.  Last  winter  I  was  enabled  to  adopt  a  much  more  simple  and  con- 
venient process  for  the  evolution  of  silicon,  which  is  as  follows: 

1358.  A  bell  glass  was  filled,  over  mercury,  with  fluosilicic  acid.     By 
means  of  a  bent  wire  a  cylindrical  cage  of  wire-gauze,  containing  a  few 
globules  of  potassium,  was  introduced  through  the  mercury  into  the  cavity 
of  the  bell,  and  supported  in  a  central  position.    A  knob  of  iron  was  welded 
to  the  end  of  a  rod,  of  the  same  metal,  so  recurved  as  to  reach  the  cage 
with  ease.     Having  been  heated  nearly  white-hot,  this  knob  was  passed 
through  the  mercury,  so  as  to  touch  the  cage.     By  these  means  the  potas- 
sium having  been  made  to  enter  into  combustion  with  the  fluorine,  the  sili- 
con was  evolved.     Much  of  this  substance  remained  attached  to  the  cage  in 
combination  with  fluoride  of  potassium.     From  the  impurities,  with  which 
it  was  thus  associated,  the  silicon  was  separated  by  washing  in  water  and 
digestion  with  nitric  acid.     There  can  be  no  doubt  that  this  process  may 


SILICON.  253 

be  employed  to  evolve  boron,  by  employing  fluoboric  acid  instead  of  fluo- 
silicic  acid. 

1359.  Properties  of  Silicon. — It  is  of  a  brown- ash  co- 
lour, without  the  least  trace  of  metallic  lustre,  a  non- 
conductor of  electricity,  infusible,  and  incapable  of  being 
volatilized.     It  is  not  liable  to  be  dissolved  or  oxydized  by 
sulphuric,  nitric,  chlorohydric,  or  fluohydric  acid,  but  is 
soluble  in  a  mixture  of  nitric  and  fluohydric  acid.     When 
heated  to  redness  with  the  fixed  alkaline  carbonates,  it 
burns  vividly;  and  when  dropped  upon  the  hydrates  of 
potash,  soda,  or  baryta,  while  in  a  state  of  fusion,  it  ex- 
plodes.    Yet  it  is  unchanged  by  ignition  with  chlorate  of 
potash,  and  exercises  but  a  feeble  reaction  with  nitre,  even 
when  heated  to  redness.     In  these  respects  its  habitudes 
are  anomalous. 

1360.  When  silicon,  as  usually  obtained  by  the  aid  of 
potassium,  is  intensely  heated  in  the  air  or  in  oxygen  gas, 
it  burns  with  a  feeble  blue  flame;  but,  by  becoming  en- 
crusted with  silicic  acid,  a  portion  escapes  combustion. 
This  portion  is  rendered  harder,  denser,  and  insusceptible 
of  combustion  with  oxygen  at  the  highest  temperatures. 
Berzelius  suspects  the  greater  combustibility,  and  inferior 
density  and  hardness  of  silicon,  in  the  state  in  which  it  is 
obtained  by  the  process  above  described,  to  be  due  to  the 
presence  of  hydrogen,  derived  from  the  water  employed. 
In  this  state,  it  inflames  when  ignited  in  the  vapour  of 
sulphur,  and  forms  a  sulphide,  which  is   decomposed  by 
water  into  sulphydric  and  silicic  acid. 

COMPOUND  OF  SILICON  WITH  OXYGEN. 
Of  Silica,  or  Silicic  Acid. 

1361.  One  atom  of  silicon  with  one  atom  of  oxygen, 
each  equivalent  to  8,  forms  one  atom  of  silicic  acid,  equi- 
valent 16. 

1362.  Preparation. — Quartz  being  powdered,  and  fused 
with  three  times  its  weight  of  pearlash,  a  glass  is  obtained, 
which,  being  soluble,  forms  with  water  a  liquid,  called  for- 
merly liquor  silicum,  or  liquor  of  flints.     An  acid  being 
poured  into  this  solution,  silicic  acid,  slightly  contami- 
nated by  potash,  is  precipitated. 

1363.  To  obtain  silicic  acid,  Berzelius  advises  us  to  fuse 
in  a  platinum  crucible,  equal  parts  of  the  carbonates  of 


254  INORGANIC  CHEMISTRY. 

potash  and  soda,  and  to  add  quartz,  finely  pulverized,  in 
small  successive  portions.  The  effervescence  arising  from 
the  addition  of  one  portion,  is  allowed  to  subside  before 
adding  another,  until  effervescence  can  no  longer  be  excited. 
The  refrigerated  mass  is  dissolved  in  chlorohydric  acid, 
and  the  solution  filtered  and  evaporated  to  dryness.  To 
remove  all  traces  of  iron  or  alumina,  the  dry  mass  is  kept 
moist  with  chlorohydric  acid,  during  about  two  hours, 
and  afterwards  washed  with  hot  water,  and  then  exposed 
to  a  red-heat.  Silicic  acid  will  remain  in  a  sufficient  de- 
gree of  purity. 

1364.  Pure  silicic  acid,  in  the  well  known  form  of  rock 
crystal,  is  found  throughout  nature.     Its  usual  crystalline 
form  is  a  six-sided  prism,  terminated  by  a  pyramid  with 
six  faces. 

1365.  Properties. — Pure  silicic  acid  is  white,  tasteless, 
and  inodorous,  and  has  a  specific  gravity  of  2.66.'    Its 
solution  does  not  redden  litmus,  and,  when  evaporated  to 
a  certain  point,  forms  a  translucent  jelly.     It  is  soluble 
when  nascent,  but  insoluble  after  exposure  to  heat  or  de- 
siccation, or  in  its  native  crystalline  form. 

1366.  It  was  first  fused  by  myself,  in  the  year  1801,  by 
means  of  the  compound  blowpipe.      It  has  never  been 
volatilized. 

Of  Chloride  of  Silicon. 

1367.  When  silicon  is  heated  in  chlorine  it  inflames,  evolving  heat  and 
light,  and  a  chloride  of  silicon  is  formed,  which  is  a  volatile  liquid,  possess- 
ing a  sharp  and  powerful  odour.  In  consequence  of  the  absorption  of  an 
excess  of  cjilorine,  it  is  generally  coloured  yellow.  It  boils  below  212°, 
and,  by  the  addition  of  water,  is  converted  into  chlorohydric  and  silicic 
acid. 

Experimental  Illustrations. 

1368.  Silicate  of  potash,  exhibited ;  also  the  solution  of 
it,  called  liquor  silicum,  from  which  silica  is  precipitated 
by  means  of  an  acid. 

Of  Glass. 

1369.  If  the  proportions,  in  which  sand  and  alkali  are  used  as  above- 
mentioned  for  the  liquor  silicum,  be  reversed,  the  insoluble  compound  of 
silicic  acid  and  alkali,  known  under  the  name  of  glass,  is  obtained,  which, 
however  pure  the  materials,  has  a  slight  tinge  of  green.     This  is  removed 
by  a  due  admixture  of  the  red  oxide  of  lead,  and  black  oxide  of  manganese. 

1370.  Annealing  Process. — A  sudden  diminution  of  the  quantity  of 


SILICON.  255 

caloric  among  the  exterior  particles  of  a  thick  piece  of  glass  in  a  state  of 
ignition,  is  not  attended  by  a  corresponding  diminution  of  the  quantity  of 
this  principle  among  the  particles  within,  owing  to  the  slowness  with  which 
glass  conducts  heat.  Hence,  there  can  neither  be  a  general  coherence,  nor 
a  uniform  arrangement  among  the  particles ;  unless  the  cooling  be  very 
slow,  so  as  to  allow  the  refrigeration,  within  and  without,  to  be  nearly  si- 
multaneous. As  it  never  can  be  perfectly  simultaneous,  the  annealing 
will  always  be  defective,  other  things  being  equal,  in  proportion  as  the  glass 
is  thicker.  Were  the  particles  subjected  to  radiant  heat  only,  the  process 
would  be  more  effectual ;  as  this,  when  proceeding  from  incandescent  sur- 
faces, has  been  ascertained  to  penetrate  and  even  to  pass  through  glass. 

1371.  By  gradually  making  up  a  fire  of  charcoal,  at  about  four  inches 
distance  on  each  side  of  a  glass  tube  of  about  an  inch  and  a  quarter  in 
thickness,  and  with  a  very  small  bore,  I  was  enabled  to  heat  it  red-hot, 
without  causing  a  fracture.     From  its  situation,  it  was  subjected  to  radiant 
heat  only. 

1372.  By  opening  a  perpendicular  hole  in  an  anthracite  fire,  I  have  been 
enabled,  with  little  delay,  to  introduce  the  beaks  of  glass  retorts  of  two  or 
three  gallon  in  capacity,  without  causing  a  fracture.     Thus  situated,  the 
glass  soon  becomes  almost  fluid,  so  that  by  its  own  weight  the  lower  por- 
tion is  drawn  downwards  into  a  tapering  tube,  and  would  be  made  to  fall 
off  were  the  beak  not  removed  from  the  fire.     If  removed  in  due  time,  the 
body  of  the  retort  may  be  so  held  as  to  cause  the  tapering  portion  of  the 
beak  to  form  such  an  angle  with  the  other  part,  as  to  be  capable  of  enter- 
ing the  tubulure  of  another  retort,  as  described  in  one  of  the  processes  for 
procuring  pure  chlorohydric  acid.  (891.) 

1373.  By  like  means,  the  beaks  of  broken  retorts,  or  any  piece  of  a  glass 
tube,  may  be  made  to  taper,  to  be  elongated  so  as  to  be  inserted  through 
the  tubulure  of  a  retort,  and  to  serve,  consequently,  when  luted  to  the  tubu- 
lure, for  the  introduction  of  sulphuric  acid,  in  various  processes  besides  that 
to  which  allusion  is  above  made. 

1374.  Prince  Rupert's  Drops. — When  glass,  in  a  state  of  fusion,  is 
dropped  into  water,  the  defective  states  of  cohesion  and  arrangement,  con- 
sequent to  the  want  of  annealing,  are  at  the  maximum.     Such  drops  have, 
long  been  known  under  the  name  of  Prince  Rupert's  drops.     It  is  only 
necessary  to  break  off  the  slender  filament  in  which  the  mass  terminates, 
in  order  to  cause  an  explosive  dispersion  of  the  whole  into  a  coarse  powder. 

1375.  The  cohesion  of  the  particles  in  glass  tubes,  is  often  nearly  as  im- 
perfect as  in  Prince  Rupert's  drops.     The  slightest  mark  from  a  file  on  the 
interior  surface,  or  even  wiping  them  out,  especially  if  a  metallic  wire  be 
employed,  may  cause  them  to  break  into  pieces.     Sometimes  the  fracture 
ensues  immediately,  at  other  times,  not  till  many  hours  have  intervened. 

COMPOUNDS  OF  FLUORINE  WITH  HYDROGEN,  BORON, 
AND  SILICON. 

1376.  Fluorine  has  been  briefly  noticed,  (746,  &c.)     I 
deferred  treating  of  the  interesting  compounds  formed  by 
this  element  with  hydrogen,  boron,  and  silicon,  until  the 
student  should  be  acquainted  with  those  substances. 

1377.  The  three  fluorides  referred  to  are  called  seve- 
rally jluoJiydric,  Jluoboric,  and  Jluosilicic  acid.   (862). 


256  INORGANIC  CHEMISTRY. 

Of  Fluohydric  Acid,  generally  called  Hydrofluoric  Acid.  (856.) 

1378.  Fluorine  exists  in  nature  in  union  with  the  metals  of  the  earths 
and  alkalies,  especially  with  calcium,  a  metal  of  which  lime  is  the  oxide. 
Such  compounds  are  called  fluorides.     The  remarkable  mineral,  called 
Derbyshire  or  fluor  spar,  is  a  fluoride  of  calcium. 

1379.  Not  long  since,  Derbyshire  spar  was  considered  a  compound  of 
lime  with  an  acid,  called  fluoric  acid,  and  supposed  to  consist  of  oxygen 
and  an  unknown  radical.    Mr.  Ampere  first  suggested  the  present  doctrine, 
which  was  soon  adopted  by  Sir  H.  Davy,  and  is  now,  I  believe,  universally 
sanctioned. 

1380.  Preparation. — When  fluoride  of  calcium  is  pulverized,  and  heated 
in  a  leaden  retort  with  twice  its  weight  of  concentrated  sulphuric  acid,  the 
water  in  combination  with  the  acid  is  decomposed.     The  oxygen  and  acid 
form  sulphate  of  lime  with  the  calcium;  while  the  hydrogen  produces  with 
the  fluorine,  fluohydric  acid,  which  passes  over  in  the  form  of  a  very  vola- 
tile acid  vapour,  and  may  be  condensed  in  a  leaden  or  silver  receiver,  sur- 
rounded by  a  mixture  of  snow  and  salt.     If  received  in  water,  it  condenses 
without  refrigeration,  and  forms  a  diluted  acid. 

1381.  Properties. — Fluohydric  acid  is  a  colourless,  limpid  liquid,  which 
boils  at  a  little  below  60°.    When  anhydrous,  its  specific  gravity  is  1.0609. 
It  is  so  volatile,  that,  in  a  close  apartment  it  cannot  be  decanted  without 
subjecting  the  operator  to  intolerable  fumes.     This  operation  must  be  per- 
formed where  there  is  a  current  of  air  to  carry  them  off. 

1382.  It  ulcerates  the  skin  with  peculiar  activity,  and  corrodes  glass  so 
as  to  trace  its  course  indelibly,  in  running  over  the  surface.     It  must  be 
kept  in  vessels  of  silver  or  lead,  accurately  closed.     When  received  in 
water  it  is  absorbed,  forming  aqueous  fluohydric  acid,  and  is  then  more 
easily  preserved. 

1383.  One  atom  of  hydrogen,  equivalent  1,  with  one  atom  of  fluorine, 
equivalent  18,  is  supposed  to  form  one  atom  of  fluohydric  acid,  equiva- 
lent 19. 

Experimental  Illustrations. 

1384.  Powdered  fluoride  of  calcium,  heated  with  sul- 
phuric acid  in  a  leaden  retort,  adapted  to  a  receiver  sur- 
rounded by  a  mixture  of  snow  and  salt.     Same  process, 
substituting  a  receiver  with  water,  by  means  of  Knight's 
apparatus.     Effect  of  fluohydric  acid  upon  glass. 

Of  Fluoboric  Acid. 

1 385.  Preparation. — It  may  be  obtained  by  intensely  heating  a  mixture 
of  two  parts  of  powdered  fluoride  of  calcium,  with  one  of  vitrified  boric 
acid,  in  an  iron  tube.     One  part  of  the  boric  acid  is  decomposed,  the  oxy- 
gen of  which,  and  the  remaining  portion  of  the  acid,  form  borate  of  lime 
with  the  calcium;  while  the  boron  unites  with  the  fluorine,  forming  fluo- 
boric  acid  gas,  which  must  be  received  over  mercury.     Fluoboric  acid  gas, 
may  likewise  be  procured,  by  heating  in  a  glass  retort  two  parts  of  fluoride 
of  calcium  and  one  of  boric  acid,  with  twelve  parts  of  concentrated  sulphu- 
ric acid.     Berzelius,  however,  states  that,  when,  obtained  by  this  method,  it 
is  contaminated  by  fluosilic  acid,  arising  from  the  action  of  the  fluorine  on 


SILICON.  257 

the  glass.     This  might,  however,  be  avoided  by  performing  the  operation 
in  a  leaden  retort. 

1387.  Dr.  Thomson  states  that  the  best  method  of  obtaining  fluoboric 
acid  gas,  is  one  which  was  suggested  by  Berzelius.     Boric  acid  is  to  be 
dissolved  in  anhydrous  fluohydric  acid,  and  a  gentle  heat  applied  to  the 
solution.     A  reciprocal  decomposition  takes  place;   the  hydrogen  of  the 
fluohydric  acid  combines  with  the  oxygen  of  the  boric  acid,  forming  water, 
while  the  fluorine  unites  with  the  boron,  and  constitutes  fluoboric  acid  gas. 

1388.  Properties. — Fluoboric  acid  is  a  colourless,  transparent  gas,  with 
a  potent  odour,  and  an  acid  taste.     It  reddens  litmus  paper,  and  is  destruc- 
tive to  life.     Its  specific  gravity  is  2.3622.     Water  absorbs  seven  hundred 
times  its  volume  of  this  gas.     When  fluoboric  acid  is  passed  into  water, 
the  oxygen  of  a  portion  of  the  water  unites  with  the  boron,  forming  boric 
acid,  while  the  hydrogen  combines  with  the  fluorine,  producing  fluohydric 
acid.     The  boric  acid  precipitates,  and  the  fluohydric  acid  combines  with 
the  undecomposed  portion  of  the  fluoboric  acid,  forming  a  compound  which 
Berzelius  designates  as  hydrofluoboric  acid,  but  which,  according  to  the 
nomenclature  which  I  have  adopted,  should  be  called  fluohydroboric  acid. 
If  we  continue  to  pass  fluoboric  acid  gas  into  the  water,  or  partially  abstract 
this  liquid  by  evaporation,  until  the  solution  of  fluoboric  acid  becomes  satu- 
rated, the  affinities  which  were  at  first  brought  into  play  are  reversed.    The 
hydrogen  of  the  fluohydric  acid  unites  with  the  oxygen  of  the  precipitated 
boric  acid,  and  the  fluorine  with  the  boron;  so  that  we  finally  obtain  a 
simple  solution  of  fluoboric  acid  in  water.     This  solution  is  at  first  fuming; 
but  on  the  application  of  heat  it  yields  up  a  fifth  part  of  its  gas,  and  then 
strongly  resembles  concentrated  sulphuric  acid  in  appearance.     Like  that 
acid,  it  carbonizes  organic  products,  in  consequence  of  its  affinity  for  water. 

1389.  Three  atoms  of  fluorine,  equivalent  54,  and  one  atom  of  boron, 
equivalent  11,  form  one  atom  of  fluoboric  acid,  equivalent  65.    (856,  &c.)  . 

Of  Fluosilicic  Acid. 

1390.  Preparation. — It  may  be  obtained  by  adding  to  the  materials  for 
evolving  fluohydric  acid,  one  half  their  weight  of  finely  powdered  glass, 
subjecting  the  mixture  to  heat  in  a  glass  retort,  and  receiving  the  product 
over  mercury ;  as  by  water  it  would  be  rapidly  absorbed. 

1391.  The  oxygen  of  the  silicic  acid  in  the  glass,  with  the  sulphuric  acid 
and  calcium,  forms  a  sulphate  of  lime ;  while  the  fluorine  and  silicon  escape 
in  the  form  of  fluosilicic  acid  gas. 

1392.  The  apparatus  which  I  employ  for  fluosilicic  acid,  is  precisely  the 
same  as  that  described  under  the  head  of  ammonia. 

1393.  Properties. — Fluosilicic  acid  is  a  transparent,  colourless  gas,  with 
a  peculiar  and  suffocating  odour,  closely  resembling  that  of  chlorohydric 
acid.    It  reddens  litmus  paper,  and  has  a  specific  gravity  of  3.5735.  When 
brought  in  contact  with  water  it  is  rapidly  absorbed,  and  a  decomposition 
takes  place,  similar  to  that  which  ensues  in  the  case  of  fluoboric  acid  under 
similar  circumstances.     Silicic  acid  is  deposited  in  the  form  of  a  gelatinous 
mass,  and  fluohydric  acid  is  produced,  which  combines  with  the  undecom- 
posed portion  of  the  fluosilicic  acid,  forming  a  compound  called  hydrofluo- 
silicic  acid,  to  which,  if  it  be  an  acid,  I  would  give  the  name  of  f.uohydro- 
silicic  acid.     If  the  water  in  combination  with  the  fluohydrosilicic  acid  be 
partially  removed  by  heat,  fluosilicic  acid  gas  escapes,  leaving  fluohydric 
acid  in  solution. 

33 


258  INORGANIC  CHEMISTRY. 

1394.  One  atom  of  fluorine,  equivalent  18,  with  one  atom  of  silicon, 
equivalent  8,  forms  one  atom  of  fluosilicic  acid,  equivalent  26. 

Experimental  Illustrations. 

1395.  Production  of  fluosilicic  acid,  shown:  also  its  ab- 
sorption by  water,  and  the  precipitation  of  silicic  acid,  as 
above  described. 

Of  the  Reaction  of  Fluohydric  Acid  with  Fluoboric  and  Fluosilicic 
Acid,  and  of  the  Nomenclature  of  the  Compounds  formed  by  the  latter 
on  meeting  with  Oxibases. 

1396.  The  union  which  ensues  between  fluohydric  acid,  and  either  fluo- 
boric,  or  fluosilicic  acid,  agreeably  to  the  preceding  statement,  may  appear 
anomalous,  in  the  way  in  which  it  has  hitherto  been  treated.     If,  however, 
I  am  correct  in  my  mode  of  defining  the  difference  between  an  acid  and  a, 
base,  (631,)  the  combinations  in  question  will  not  prove  to  be  anomalous. 
I  deem  it  consistent  to  suppose  that  a  fluobase  of  hydrogen  unites,  in  the 
one  case,  with  fluoboric  acid,  in  the  other  with  fluosilicic  acid;  so  that  fluo- 
hydroboric  acid  might  be  called  fluoborate  of  the  fluobase  of  hydrogen,  or 
more  briefly,  fluoborate  of  hydrogen;  and  in  like  manner,  fluohydrosilicic 
acid  would  be  called  fluosilicate  of  the  fluobase  of  hydrogen,  or  briefly, 
fluosilicate  of  hydrogen. 

1397.  When  either  fluohydroboric  acid,  or  fluohydrosilicic  acid,  or  in 
other  words  the  fluoborate  or  fluosilicate  of  the  fluobase  of  hydrogen,  is 
brought  into  contact  with  an  oxibase,  the  radical  of  the  latter  takes  the  place 
of  the  hydrogen,  which,  with  its  oxygen,  forms  water.     Thus,  in  the  case 
of  potash,  there  would  result  a  fluobase  of  potassium,  usurping  the  place  of 
the  fluobase  of  hydrogen ;  and  of  course  either  a  fluosilicate,  or  fluoborate 
of  potassium  must  be  formed.     Agreeably  to  the  Berzelian  nomenclature, 
these  compounds  are  double  salts,  the  name  of  one  being  in  the  French 
translation,    "fluorure   borico-potassique"    that  of  the  other,    "fluorure 
silico-potassique."     Many  analogous  salts,   formed   by  the   acids  under 
consideration,  with  salifiable  substances,  are  mentioned  by  Berzelius ;  also 
many  others,  in  which  other  radicals,  in  union  with  fluorine,  play  a  part 
analogous  to  that  performed  by  silicon  and  boron,  in  the  salts  above  men- 
tioned. 

1398.  There  are  instances  in  which  compounds,  usually  called  bases,  act 
as  acids.     Of  course  it  is  consistent  that  compounds,  usually  called  acids, 
should  in  some  instances  act  as  bases.     In  this  respect,  a  striking  analogy 
may  be  observed  between  the  union  of  the  oxide  of  hydrogen  (water)  with 
the  oxacids  and  oxybases ;  and  that  of  fluoride  of  hydrogen  with  fluacids 
and  fluobases.     According  to  Berzelius,  water  acts  as  a  base  to  oxacids;  as 
an  acid  to  oxibases.     So  I  conceive  the  fluoride  of  hydrogen  acts  as  a  base 
in  the  cases  above  noticed,  while  it  acts  as  an  acid  in  the  compound  of  hy- 
drogen, fluorine,  and  potassium,  called  by  Berzelius  "Jluorure  potassique 
acide."     This  compound  I  would  call  a  fluohydrate  of  the  fluobase  of  po- 
tassium, or  more  briefly,  fluohydrate  of  potassium ;  as  we  say  sulphate  of 
copper,  instead  of  the  sulphate  of  the  oxide  (or  oxybase)  of  copper. 


ZIRCONION.  259 

SECTION  VII. 

OF  ZIRCONION,  OR  ZIRCONIUM. 

1399.  There  is  a  stone,  known  under  the  name  of  the  jargon  or  zircon 
of  Ceylon,  from  which  Klaproth  extricated  an  earth,  to  which  the  name  of 
zirconia  was  given.  This  earth  is  an  oxide  of  an  elementary  body,  which 
has  been  called  zirconion,  or  zirconium.  The  termination  in  um  being  now 
only  applied  by  chemists  to  the  names  of  substances  having  the  metallic 
character,  I  think  that  it  has  been  erroneously  associated  with  the  name  of 
the  element  in  question,  since  its  pretensions  to  that  character  are  not  higher 
than  those  of  carbon. 

OF  METALLIC  RADICALS. 

1400.  It  is  to  metallic  radicals  that  I  deem  it  expedient 
in  the  next  place  to  direct  attention.     Less  than  thirty 
years  ago,  the  line  of  demarcation  between  metals  and 
other  bodies  was  easily  drawn.    There  was  then  no  known 
metal  which  had  a  specific  gravity  less  than  six;  and  of 
other  bodies,  none  of  which  the  specific  gravity  was  as 
high  as  five.     But   the  discovery  of  alkalifiable  metallic 
radicals,  having  a  specific  gravity  less  than  that  of  water, 
annihilated  the  barrier  which  had  been  established  on  the 
basis  of  superior  gravity. 

1401.  Peculiar  brilliancy  and  opacity  were  in  the  next 
place  appealed  to  as  the  means  of  discrimination;  and  like- 
wise that  superiority  in  the  power  of  conducting  heat  and 
electricity,  which  was  so  remarkable  in  substances  of  a 
decidedly  metallic  character.     Yet  so  difficult  has  it  been 
to  draw  the  line  between  metallic  and  non-metallic  radi- 
cals, that  bodies  which  are  by  some  authors  placed  in  one 
class,  are  by  others  included  in  the  other.     Thus  seleni- 
um, silicon,  and  zirconion  have  by  some  chemists  been 
comprised  among  the  metals,  by  others  among  non-metallic 
bodies.     In  fact  nature  has  not  qualified  her  bodies  for 
distinct  classification.     It  is  true  that  there  are  those  of 
which  the  prominent  features  or  qualities  are  so  strikingly 
different,  that  we  are  at  first  encouraged  to  think  that  by 
associating  similar  substances  with  each,  we  shall  form 
classes  not  liable  to  be  confounded.     Thus  gold  possesses, 
in  a  high  degree,  all  the  attributes  of  a  metal,  while  sulphur 
is  totally  devoid  of  them;  yet  arsenic,  as  being  decidedly 
metallic,  may  on  the  one  side  be  classified  with  gold  in 


260  INORGANIC  CHEMISTRY. 

preference  to  sulphur;  while  on  the  other  hand,  between 
arsenic  and  sulphur,  there  is  in  many  respects  a  much 
greater  analogy  than  between  arsenic  and  gold.  In  fact, 
tellurium,  which  had  been  always  classified  and  is  still 
considered  as  a  metal,  is  now  associated  by  Berzelius,  in 
his  amphigen  class,  with  oxygen,  selenium,  and  sulphur, 
and  has,  in  consequence,  been  treated  of  by  me  as  a  basa- 
cigen  body. 

1402.  Metals  were  formerly  distinguished  as  metals,  and 
semi-metals;  the  latter  appellation  having  been  employed 
to  designate  such  as  were  wanting  in  the  mechanical  pro- 
perties of  malleability  and  ductility.     Again,  the  metals 
which  were  endowed  with  the  properties  just  mentioned, 
were  divided  into  noble  and  base.     The   noble  metals, 
sometimes  called  precious,  from  their  superior  value,  were 
distinguished  from  the  others  by  their  insusceptibility  of 
injury  from  fire,  moisture,  or  air.     Silver  and  gold  were, 
about  a  century  ago,  the  only  known  metals  meriting  the 
name  of  noble,  upon  the  grounds  which  I  have  mentioned. 
To  these  platinum  was  subsequently  added,  and  latterly 
palladium,  nickel,  iridium,  and  rhodium,  have  been  found  to 
have  analogous  pretensions,  agreeably  to  the  ideas  in  obe- 
dience  to   which   the   epithet   was   originally   employed. 
Subsequently  chemical  properties  became  better  known, 
and  metals  were  associated  not  only  in  accordance  with 
their  own  obvious  characteristics,  but  also  with  a  view  to 
their  oxides,  which  in  many  cases  are  the  only  forms  under 
which  they  are  met  with  in  nature,  or  employed  in  the 
arts.     Accordingly  the  metals  are  now  generally  divided 
with  a  view  to  their  susceptibility  of  oxidizement,  or  the 
character  of  their  oxides.     Among  the  oxides  alluded  to, 
there  are  some  of  which  the  characteristics  are  so  differ- 
ent, that  there  can  be  no  hesitation  in  classifying  them 
separately.     Yet  in  other  members  of  the  same  class,  the 
characteristics  by  which  they  are  distinguished  are  so 
feeble,  that  a  diversity  of  opinion  has  existed  as  to  the 
genera  to  which  they  belong. 

1403.  I  propose  to  divide  metallic  radicals  into  the  four 
following  classes: 

First,  metals  of  the  earths  proper. 

Second,  metals  of  the  alkaline  earths. 

Third,  metals  of  the  alkalies,  or  alkalifable  metals. 

Fourth,  metals  proper. 


ZIRCONION.  261 

1404.  I  shall  employ  the  words  noble  to  distinguish 
metals   not  liable   to  be   tarnished   by  exposure  to  fire, 
water,  or  air;  as,  for  instance,  gold,  platinum,  indium, 
palladium,  rhodium,  silver,  and  nickel. 

1405.  Metals  proper  are  by  Berzelius  divided  into  elec- 
tro-negative or  acidifiable  metals,  and  electro-positive  or 
basifiable  metals.     Under  the  former  head  he  places  sele- 
nium, arsenic,  molybdenum,  tungsten,  antimony,  tellurium, 
columbium  or  tantalum,  and  titanium.     Under  the  head  of 
electro-positive  or  basifiable  metals,  he  places  gold,  plati- 
num, osmium,  iridium,  palladium,  silver,  mercury,  copper, 
bismuth,  tin,  lead,  cadmium,  zinc,  nickel,  cobalt,  iron,  man- 
ganese, and  uranium. 

1406.  I  am  under  the  impression  that  each  of  the  fol- 
lowing metals,  being,  agreeably  to  the  same  authority, 
capable   of  forming   with   a   halogen    body   the   electro- 
negative ingredient  in  a  double  salt,  should  be  considered 
as  acidifiable;  namely,  gold,  platinum,  silver,  palladium, 
iridium,  rhodium,  uranium,  chromium,  titanium,  molybde- 
num, manganese,  osmium,  mercury,  nickel,  copper,  iron, 
and  zinc. 

1407.  When  the  objects  which  it  may  be  desirable  to 
study,  are  too  numerous  and  complicated  in  proportion  to 
the  time  and  attention  which  we  have  to  bestow;  we  may 
employ  such  time  as  we  have,  either  in  a  cursory,  super- 
ficial, and  indiscriminate  examination  of  the  whole,  or  in 
a  more  thorough  study  of  the  more  important  parts.     Of 
the  two  courses  I  cannot  conceive  that  any  judicious  per- 
son would  hesitate  in  choosing  the  latter. 

1408.  Under  this  impression  I  shall  treat  particularly  of 
the  twelve  metals  proper,  included  in  the  following  list — 
gold,  platinum,  silver,  mercury,  copper,  lead,  tin,  iron,  zinc, 
antimony,  bismuth,  and  arsenic.     Besides  the  metals  thus 
mentioned,  there  are  in  the  same  class,  palladium,  rhodium, 
iridium,  osmium,  nickel,  cadmium,  chromium,  cobalt,  co- 
lumbium,   manganese,    molybdenum,    titanium,    tungsten, 
uranium,  and  vanadium.     Of  these  1  shall  give  only  a 
brief  account,  with  descriptions  and  illustrations  of  their 
striking  and  useful  properties,  where  such  exist. 

1409.  I  subjoin  a  list  of  metallic  radicals,  comprising  all  the  metals 
excepting  tellurium;  which  has  been  treated  of  as  a  basacigen  element. 
So  far  as  our  knowledge  extends,  the  dates  at  which  these  metals  severally 
became  known,  and  the  names  of  their  discoverers,  are  mentioned. 


262 


INORGANIC  CHEMISTRY. 


Table  of  Metals  classified  as  Metallic  Radicals,  also  of  the  dates  at 
which  they  were  discovered. 


Names  of  Metals. 

Authors  of  the  discovery. 

Dates  of 
the  Discovery. 

Gold      .          .                1 

Silver 

Iron 

Copper          .               }> 

Known  to  the  Ancients. 

Mercury 

Lead     . 

Tin       .                      J 

Antimony     . 
Bismuth 
Zinc     . 

Described  by  Basil  Valentine 
Described  by  Agricola 
First  mentioned  by  Paracelsus 

1490 
1530 
IGth  century. 

Arsenic         .               ) 
Cobalt           .               5 

Brandt            

1733 

Platinum 

Wood,  assay-master,  Jamaica 

1741 

Nickel 

Cronstadt       

1751 

Manganese 
Tungsten 
Molybdenum 

Gahn  and  Scheele          .... 
D'Elhuyart     ...... 
Hielm     

1774 
1781 

1782 

Uranium 

Klaproth         

1789 

Titanium 

Gregor            .... 

1791 

Chromium    . 

Vauquelin       

1797 

Columbium 

Hatchett         

1802 

Palladium     .               ) 

Wollaston       .        .         .         . 

1803 

Rhodium      .               5 

Iridium 

Descotils  and  Smithson  Tennant 

1803 

Osmium 

Smithson  Tennant         .... 

1803 

Cerium 

Hisinger  and  Berzelius 

1804 

Potassium    .              "| 

Sodium 

Barium         .               ^ 

Davy      

1807 

Strontium     . 

Calcium        .              J 

i 

Cadmium 

Stromeyer      ...                 . 

1818 

Lithium 

Arfwedson     

1818 

Aluminium                 ) 

Glucinium   .               > 

Wohler          

1828 

Yttrium        .               ) 

Thorium       . 

1829 

Magnesium 
Vanadium    . 

Bussy      
Sefstrb'm         

J829 
1830 

Of  the  Generic  Characteristics  of  the  Metals. 

1410.  When  newly  cut,  metals  have  a  peculiar  lustre.     They  are  the 
best  conductors  of  heat  and  electricity ;  the  worst  radiators  and  best  reflec- 
tors of  heat.     All  combine,  directly  or  indirectly,  with  all  the  basacigen 
bodies  in  one  or  more  proportions.  (633.)     They  are  all  susceptible  of 
solidity  and  fluidity,  and  probably  of  the  aeriform  state.     Mercury  and 
arsenic  are  easily  volatilized ;  and  gold,  silver,  and  platinum,  though  very 
difficult  to  burn  or  volatilize,  are  nevertheless  dissipated  by  means  of  the 
compound  blowpipe,  galvanism,  or  electricity. 

Of  Properties  possessed  by  some  Metals,  but  not  by  others. 

1411.  The  properties  which  come  under  this  head,  are  permanency  of 
lustre  in  the  fire  and  air ;  malleability ;  ductility ;  elasticity ;  sensibility  to 


ZIRCONION.  263 

the  magnet ;  susceptibility  of  the  welding  process,  and  of  acquiring,  by  a 
union  with  carbon,  silicon,  or  aluminium,  the  capability  of  hardening  by 
being  suddenly  refrigerated  from  a  red-heat ;  also  of  being  hardened  by 
the  hammer,  and  of  being  restored  by  heat  in  the  annealing  process. 

1412.  The  metals  remarkable  for  permanency  of  lustre,  are  gold,  plati- 
num, iridium,  palladium,  rhodium  and  nickel,  called  on  that  account  noble, 
or  perfect.     Those  principally  remarkable  for  malleability,  are  gold,  silver, 
platinum,  copper,  palladium,  nickel,  iron,  tin,  cadmium,  and  lead.     Among 
these,  iron  and  platinum  only,  can  be  advantageously  hammered  at  a  very 
high  temperature. 

1413.  The  metals   distinguished  for  elasticity,  are  iron,  copper,  and 
silver.     Iron,  in  the  state  of  steel  when  duly  tempered,  is  pre-eminent  for 
this  property. 

1414.  The  metals  remarkable  for  ductility,  are  gold,  iron,  either  pure, 
or  as  steel,  silver,  copper,  platinum,  tin,  and  lead.     In  large  rods  or  pipes, 
lead  and  tin  are  the  most  ductile. 

1415.  The  magnetic  metals  are  iron,  whether  pure,  in  the  state  of  steel, 
or  in  that  of  protoxide,  nickel,  and  cobalt.     Those  susceptible  of  the  weld- 
ing process,  are  iron  and  platinum.     Iron  only  is  capable,  of  uniting  with 
carbon,  silicon,  or  aluminium,  and  hardening  consequently  by  quick  re- 
frigeration.    Gold  and  platinum  are  distinguished  by  their  superior  gravity, 
which  is  between  two  and  a  half,  and  three  times  as  great  as  that  of  iron, 
tin,  or  zinc. 

1416.  All  the  metals  have  a  specific  gravity  greater  than  five,  if  we  ex- 
cept those  of  the  earths  and  alkalies. 

1417.  Of  the  Annealing  Process. — Malleability,  ductility,  and  tough- 
ness, in  metals  susceptible  of  the  annealing  process,  are  probably  dependent 
on  the  quantity  of  caloric  remaining  in  combination  with  their  particles, 
while  in  the  solid  state.     When  malleable  metals  are  hammered,  they  give 
out  heat,  and  become  harder,  more  rigid,  elastic,  and  dense,  until  they  ac- 
quire a  certain  maximum  of  density.     This  being  attained,  they  are  frac- 
tured if  the  hammering  be  carried  further.      Exposed  to  the  fire  until 
softened,  they  are  found  on  cooling  to  liave  regained  the   properties  of 
which  percussion  had  deprived  them ;  and  they  may  be  again  condensed, 
heated,  and  hardened,  by  the  hammer. 

1418.  Of  Alloys. — This  name  is  given  to  the  compounds  formed  by 
the  union  of  different  metals.     There  is  always  copper  in  gold  and  silver 
coin;  and  in  the  metal  employed  under  those  names  by  the  smiths  and 
jewellers,  there  are  various  proportions  of  the  baser  metal.     Brass  consists 
of  copper  and  zinc ;  pewter,  of  lead  and  tin,  or  of  tin,  copper,  and  anti- 
mony. 

Of  the  Oxidalility  of  Metals  by  Exposure  to  Air  or  Moisture,  with  or 

without  Heat. 

1419.  Gold,  silver,  platinum,  palladium  and  rhodium,  do  not  become  oxi- 
dized by  exposure  to  water  or  oxygen  at  any  temperature ;  and  when  oxi- 
dized by  other  means,  on  being  ignited  are  reduced.* 

*  The  verb  to  reduce,  has  long  been  employed  by  chemists  to  signify  the  deoxi- 
dizement  of  a  metallic  oxide,  so  as  to  effect  its  restoration  to  the  metallic  state,  or 
that  of  a  regulus,  to  use  another  word  which  I  shall  also  employ,  to  avoid  circumlo- 
cution; although  it  is  now  somewhat  antiquated.  The  verb  to  revive  has  been  used 
in  the  same  sense  as  to  reduce. 


264  INORGANIC  CHEMISTRY. 

1420.  Iron,  zinc,  and  tin  are  not  oxidized  by  exposure  to  dry  air,  or  to 
water  alone,  unless  aided  by  a  red-heat.     Of  these  metals  iron  is  most 
acted  upon  by  the  joint  influence  of  air  and  moisture,  at  the  ordinary  tem- 
peratures of  the  atmosphere.     Copper,  tin,  and  lead  do  not  decompose 
water  at  any  temperature,  but  are  oxidized  at  a  red-heat,  or  at  temperatures 
sufficient  for  their  fusion.     Mercury  is  not  oxidized  by  water  under  any 
circumstances.     It  is  oxidized  by  agitation,  or  by  a  heat  just  below  its 
boiling  point,  with  access  of  air;  but  when  distilled,  it  abandons  the  oxygen 
which  may  have  united  with  it  previously. 

OF  METALS  OF  THE  EARTHS  PROPER. 

1421.  The  metals  included  under  this  head  are  alumi- 
nium, glucinium,  yttrium  and  thorium. 

SECTION  I. 

OF  ALUMINIUM. 

1422.  A  chloride  of  aluminium  was  obtained  by  Oersted, 
by  subjecting  to  a  current  of  chlorine,  an  intimate  mixture 
of  alumina  and  carbon,  heated  in  a  porcelain  tube.     The 
affinity  of  the  carbon  for  the  oxygen  of  the  earth,  and  of 
the  chlorine  for  the  metallic  radical,  was  productive  of  car- 
bonic oxide  in  the  state  of  gas,  and  the  chloride  of  alu- 
minium  in   the  state  of  vapour;   of  course   the   former 
escapes,  while  the  latter  condenses,  within  a  glass  tube 
purposely  luted  to  that  in  which  the  materials  are  ignited, 
as  already  explained. 

1423.  By  heating,  with  potassium,  the  chloride  obtained 
by  the  process  above  mentioned,  Wohler  liberated  alumi- 
nium through  the  superior  affinity  of  potassium  for  chlo- 
rine. 

1424.  I  have  repeated  this  process  so  far  as  to  obtain 
the  chloride,  and  to  expose  it  to  reaction  with  potassium, 
but  I  found  it  difficult  to  extract  the  aluminium  from  the 
residual  mass  to  a  satisfactory  extent. 

1425.  Properties  of  Aluminium. — In  the  state  in  which 
Wohler  obtained  this  metal,  it  is  described  as  a  gray  pow- 
der much  resembling  that  of  platinum.     Some  little  facets, 
which  have  sufficient  magnitude  to  be  distinguished,  after 
compression  under  the  burnisher,  display  a  metallic  bril- 
liancy.    Yet  in  the  pulverulent  form,  the  metal  has  so  little 
power  to  conduct  electricity,  that,  when  interposed  in  the 
galvanic   circuit,  it  interrupts  the  action.     It  is  alleged, 
however,  that,  in  a  minute  state  of  division,  iron  is  a  non- 


ALUMINIUM.  265 

conductor  of  electricity,  and  Turner  states  that,  by  fusion, 
aluminium  becomes  a  conductor.  It  appears  to  me  that 
at  best  its  claims  to  the  metallic  character  are  not  superior 
to  those  of  carbon  in  the  form  of  plumbago.  Its  atomic 
weight  is  14. 

1426.  Aluminium  burns  with  a  heat  so  intense,  as  to 
cause  the  fusion  of  the  resulting  oxide,  which  becomes,  on 
cooling,  hard  enough  to  cut  glass.     Aluminium  is  not  oxi- 
dized when  water  is  evaporated  from  it  at  a  gentle  heat. 
At  a  boiling  heat  it  evolves  hydrogen  feebly,  and  the  evo- 
lution, having  once  commenced,  continues  for  some  time 
after  refrigeration.     With  concentrated  nitric  or  sulphuric 
acid,  aluminium  has  no  reaction  at  ordinary  temperatures; 
but,  assisted  by  heat,  it  forms  a  sulphate  or  nitrate,  ac- 
quiring oxygen  from  one  portion  of  the  acid,  and  uniting 
with  the  remainder.     When  subjected  to  a  solution  of  pot- 
ash, soda,  or  ammonia,  aluminium,  by  the  decomposition 
of  the  water,  is  converted  into  alumina,  which  unites  with 
the  alkali,  forming  an  aluminate.     On  this  account,  in  pre- 
paring aluminium,  there  should  not  be  an  excess  of  potas- 
sium; and  any  potash  produced  during  the  process,  should 
be  quickly  removed  by  the  employment  of  a  quantity  of 
water  no  larger  than  necessary. 

Of  Alumina. 

1427.  This  earth  is  found  nearly  pure  in  the  gems  called 
by  jewellers  oriental,  and  classed  by  Bronguiart,  under  the 
head  of  Corindon  Telesie.     The  ruby,  sapphire,  amethyst, 
and  topaz,  of  the  most  beautiful  kinds,  are  thus  designated. 
Of  all  stony  minerals  they  have  the  highest  specific  gra- 
vity, and  are  only  inferior  to  the  diamond  in   hardness. 
Differing  from  each  other  only  in  colour,  they  yield  by  ana- 
lysis little  else  than  pure  alumina.     There  are  other  jewels 
of  the  same  name  and  colour,  which  ought  not  to  be  con- 
founded with  those  here  alluded  to.     As  an  ingredient  in 
clay,  which  owes  its  plasticity  and  all  its  striking  qualities 
to  alumina,  this  earth  enters  largely  into  the  structure  of 
the  terrestrial  globe. 

1428.  The  spinelle  ruby,  a  precious  stone,  and  Gahnite, 
are   aluminates, — the   former  of  magnesia,  the  latter   of 
zinc;  in  which,  however,  there  are  six  times  as  many  atoms 
of  alumina,  as  of  the  other  constituent. 

34 


266  INORGANIC  CHEMISTRY. 

1429.  There  are  two  native  forms  of  hydrate  of  alumina; 
one  found  in  the  United  States,  in  the  form  of  a  stalactite, 
white  and  semitransparent,  called  Gibbsite;  the  other  in 
Siberia,  called  disapore,  from  the  property  of  flying  into 
pieces,  or  even  powder,  when  heated,  in  consequence,  no 
doubt,  of  the  vaporization  of  the  combined  water. 

1430.  Preparation. — Berzelius  alleges  that  the  alum  of 
commerce,  if  it  contain  oxide  of  iron,  should  be  dissolved 
and  recrystallized  several  times;  or  a  solution  being  made 
and  allowed  to  stand  for  some  time,  the  oxide  of  iron  is 
precipitated  in  yellow  flocks.     To  the  solution  of  alum  at 
a  boiling  heat,  a  solution  of  carbonate  of  potash  is  to  be 
added  in  excess,  and  the  whole  is  to  be  digested  at  a  mo- 
derate temperature,  to  decompose  any  supersulphate  of 
alumina  which  the  alkali  may  have  precipitated.     The 
precipitate,  after  having  been  collected  and  well  washed 
upon  a  filter,  is  to  be  redissolved  in  chlorohydric  acid, 
and  precipitated  by  an  excess  of  ammonia,  either  caustic 
or  carbonated.     This  second  precipitation  is  necessary, 
to  get  rid  of  a  portion  of  carbonate  of  potash,  with  which 
the  alumina  forms  a  triple  combination  which  cannot  be 
decomposed  by  water.     The  precipitate  produced  as  last 
mentioned,  is  to  be  collected  and  carefully  washed.    When 
dried  it  forms  a  hydrate,  which,  by  a  red  heat,  is  con- 
verted into  pure  alumina.     One  hundred  parts  of  alum 
yield  a  little  more  than  ten  of  the  earth. 

1431.  In  France  a  species  of  alum  is  used,  in  which 
ammonia  takes  the  place  occupied  by  potash  in  the  com- 
mon alum.     By  heat,  which  expels  the  acid  and   alkali, 
pure  alumina  may  be  extricated  from  this  compound. 

1432.  Properties. — Alumina  is  white,  plastic  when  mois- 
tened, soft  to  the  touch,  adherent  to  the  tongue,  inodorous, 
insipid,  and  infusible  in  the  furnace.     It  is  the  only  earth 
which  was  fused  before  the  compound  blowpipe  was  in- 
vented.    Its  property  of  contracting  and  hardening  by 
heat,  was  noticed  when  on  the  subject  of  Wedgwood's 
pyrometer. 

1433.  It  is  remarkable  that,  although  quite  insoluble  in 
water,  this  earth  abstracts  and  retains  a  quantity  of  water 
amounting  to  15  per  cent,  of  its  weight.     It  is  on  this 
account  that,  as  an  ingredient  in  clay,  its  influence  on 
vegetation  is  so  beneficial.     During  rains  it  becomes  sa- 


ALUMINIUM.  267 

turated  with  moisture,  which  it  slowly  relinquishes  in  dry 
weather. 

1434.  There  is  a  remarkable  difference  in  the  appear- 
ance of  the  hydrate  of  alumina  as  obtained  by  precipitation 
from  a  concentrated,  or  a  weak  solution  of  alum.     In  the 
former  case  it  is  a  white,  friable,  spongy  powder,  which  is 
adherent  to  the  tongue,  and,  by  exposure  to  a  red-heat, 
parts  with  all  its  water.     In  the  latter  it  forms  a  transpa- 
rent yellow  mass,  which  breaks  by  the  heat  of  the  hand 
with  a  smooth  and  conchoidal  fracture,  does  not  adhere 
to  the  tongue,  or  swell  by  the  addition  of  water.     In  this 
state,  the  hydrate  of  alumina  does  not  part  with  all  its 
water,  even  at  a  temperature  above  that  of  redness. 

1435.  Alumina  has  a  great  affinity  for  vegetable  colour- 
ing matters,  which  it  consequently  precipitates  from  their 
solutions,  forming  the  pigments  known  under  the  name  of 
lakes. 

1436.  This  earth  and  its  salts  are  of  great  use  in  dye- 
ing, as  mordants  to  cause  the  dyes  to  adhere.    The  latter, 
in  many  cases,  have  no  affinity  for  the  organic  fibres  which 
are  to  be  dyed;  but  the  alumina,  combining  with  both  the 
dye  and  the  fibre,  associates  them  permanently. 

1437.  Alumina  is  soluble  in  solutions  of  caustic  potash 
and  soda,  and  even  in  those  of  baryta  and  strontia,  but 
dissolves  in  liquid  ammonia,  only  to  a  very  small  extent. 
Alumina  has  an  affinity  for  oxybases  so  strong,  as  to  be 
considered  as  acting  the  part  of  an  acid  in  some  instances. 
With  the  acid  and  base  of  alkaline  carbonates  it  forms 
triple  compounds,  which  will  bear  a  low  red-heat  without 
expelling  the  acid,  or  producing  a  more  intimate  union 
between  the  earth  and  alkali. 

1438.  The  affinity  of  alumina  for  magnesia  is  so  strong 
that  when  separated  simultaneously  from  a  common  sol- 
vent, the  former  cannot  be  taken  up  entirely  by  the  alkali, 
by  which  the  separation  is  effected.     If  magnesiferous 
alumina,  after  having  experienced  a  red-heat,  be  subjected 
to  chlorohydric  acid,  a  white  powder  remains,  which  is  an 
aluminate  of  magnesia.   - 

1439.  Three  properties  serve  to  detect  alumina;  first,  its 
affinity  for  potash,  and  consequent  solubility  in  a  solution 
of  that  alkali ;  secondly,  the  property  which  it  has  of  form- 
ing with  sulphuric  acid  and  potash,  alum,  so  readily  recog- 
nised by  its  crystallization  and  taste;  thirdly,  the  property 


268  INORGANIC  CHEMISTRY. 

of  producing   a   fine  blue   colour,  when  moistened  with 
nitrate  of  cobalt,  and  exposed  to  a  strong  heat. 

1440.  In  the  habitudes  of  this  substance,  we  have  an 
exemplification  of  the  commutable  character  of  electro- 
chemical characteristics.    While  writh  the  alkalies  and  al- 
kaline earths  it  performs  the  part  of  an  acid,  with  various 
acids  it  acts  as  a  base,  forming  with  them  compounds, 
both  natural  and   artificial.     Among  the  former  is  the 
mineral  generally  designated  as  feldspar,  which  is  com- 
posed of  silicate  of  alumina,  and  silicate  of  potash.    Porce- 
lain is  an  artificial  silicate  of  alumina.     Its  existence  as  a 
base  in  alum  has  been  mentioned. 

1441.  Alumina  was  named  from  alumen,  the  Latin  ap- 
pellation for  alum.     The  specific  gravity  of  alumina  is  2. 
It  is  composed  of  two  atoms  of  aluminium,  equivalent  28, 
and  three  atoms  of  oxygen,  equivalent  24  =  52.     It  is, 
therefore,  a  sesquioxide. 

Experimental  Illustrations. 

1442.  Alumina,  precipitated  from  a  solution  of  alum  by 
an  alkali.    Rendered  blue  by  a  solution  of  nitrate  of  cobalt. 
Contraction  sustained  by  exposure  to  heat,  illustrated. 

Of  Chloride  of  Aluminium. 

1443.  The  chloride  of  aluminium  is  obtained  as  I  have  stated  above. 
(1422.)  It  is  partially  translucid,  lamellated  in  structure,  of  a  greenish- 
yellow  colour,  and  an  astringent  taste.  Litmus  is  reddened  by  the  action 
of  this  chloride.  It  dissolves  in  water  with  a  hissing  noise.  When  the 
solution  is  highly  concentrated,  it  deposites  crystals,  which,  being  converti- 
ble by  heat  into  alumina  and  chlorohydric  acid,  probably  consist  of  one 
atom  of  chloride  of  aluminium,  and  one  atom  of  water.  According  to 
Thenard,  the  chloride  of  aluminium  forms,  with  the  chlorides  of  potassium 
and  sodium,  compounds  indecomposable  by  a  red  heat.  These  may  be 
considered  as  formed  by  the  union  of  a  chloracid  with  a  chlorobase. 


SECTION  II. 

OF    GLUCINIUM. 

1444.  Glucinium  may  be  obtained  from  its  oxide,  glucina,  by  a  process  analogous 
to  that  above  described  for  obtaining  the  radical  of  alumina.  This  metal  resembles  alu- 
minium in  appearance,  and  in  many  of  its  properties,  but  differs  from  it  in  not  being 
susceptible  of  oxidizement  by  a  solution  of  ammonia,  or  by  boiling  water. 


YTTRIUM. THORIUM.  269 


Of  Glucina. 

1445.  Glucina  is  white  and  tasteless.     It  is  insoluble  in  water,  but  forms  with  it  a 
paste,  which  is  somewhat  adhesive,  but  not  sufficiently  so  to  be  moulded.  It  does  not 
harden  by  exposure  to  heat. 

1446.  It  is  soluble  in  the  caustic  fixed  alkalies,  but  not  in  ammonia.     It  likewise 
dissolves  in  the  alkaline  carbonates,  and  in  that  of  ammonia  especially,  by  which  it 
is  distinguished  from  alumina,  as  well  as  by  its  incapacity  to  produce  alum,  or  to  as- 
sume a  blue  colour  when  treated  with  nitrate  of  cobalt.     It  forms  also  a  fluacid, 
which,  with  the  fluoride  of  potassium,  precipitates  from  a  hot  solution  in  crystalline 

Slates,   in  the  state  of  fluoglucinate  of  potassium  (fluoride  glucinico-potassique  of 
erzelius). 

1447.  The  equivalent  of  glucina  is  26,  being  composed  of  one  atom  of  glucinium, 
equivalent  18,  and  one  atom  of  oxygen,  equivalent  8. 

1448.  Glucina  exists  in  the   emerald,  comprehending  the  beryl  and  aquamarine  : 
also  in  the  euclase.     In  consequence  of  the  peculiar  sweetness  of  its  salts,  it  was 
named  glucina,  from  y\vx.vs,  sweet. 


SECTION  III. 

OF   YTTRIUM. 

1449.  Yttrium  was  procured  by  a  process  quite  analogous  to  that  described  for  alu- 
minium.  It  has  a  more  metallic  and  crystalline  aspect  than  that  metal  or  glucinium. 
Its  habitudes  with  oxygen  and  the  acids  are  perfectly  analogous  to  those  of  the  me- 
tals above  mentioned.     It  is  liable  to  be  slowly  oxidized  in  a  solution  of  potash  by 
the  decomposition  of  water.    Like  glucinium,  it  is  not  oxidized  by  water  even  when 
boiling. 

Of  Yttria. 

1450.  Yttria  is  insipid,  infusible,  and  insoluble  in  water.     It  is  uncertain  whether 
the  yellow  tinge  which  it  usually  presents,  is  appropriate,  or  produced  by  impurities. 
It  is  rendefed  snow-white  by  the  presence  of  a  small  quantity  of  sulphuric  acid.     It 
is  heavier  than  baryta,  being  of  a  specific  gravity  approaching  to  4.842.     It  is  dis- 
tinguished from  other  earths  by  its  insolubility  in  caustic  alkalies  ;  while  it  dissolves 
in  their  carbonates,  especially  that  of  ammonia,  although  in  a  lesser  quantity  than 
glucina. 

1451.  Yttria  is  principally  characterized  by  its  susceptibility  of  precipitation  by 
cyanoferrite    of  potassium  (ferroprussiate  of  potash).     Excepting  thorina,  this  pro- 
perty is  possessed  by  no  other  earth. 

1452.  With  acids  it  forms  salts,  having  a  sweet  taste,  and  in  some  instances  the 
colour  of  the  amethyst.     In  fact,  the  best  means  of  detecting  it,  is  the  production 
with  sulphuric  acid  of  crystals  having  this  hue,  which  are  extremely  slow  to  dissolve 
in  water,  and  which  effloresce  when  heated.  Its  affinities  are  more  feeble  than  those 
of  the  alkalies  or  alkaline  earths. 

1453.  This  earth  has  been  found  only  in  three  Swedish  minerals,  —  Gadolinite, 
yttro-tantalite,  and  yttro-cerite. 

1454.  Yttrium  is  composedvof  one  atom  of  yttrium,  equivalent  32,  and  one  atom 
of  oxygen,  equivalent  8  =  40. 


SECTION    IV. 

OF  THORIUM. 

1455.  Thorium  was  first  found,  not  many  years  since,  in  a  single  locality,  in  the 
state  of  oxide  or  earth,  combined  with  silicic  acid.  It  is  in  the  island  of  Loecun 
that  it  was  met  with,  near  the  little  village  of  Berwig,  in  Norway.  It  was  found  in 
a  mineral  resembling  obsidian,  and  called  thorite,  which  contained  57  per  cent,  of 
thorina,  or  oxide  of  thorium,  and  in  addition,  lime,  magnesia,  iron,  manganese,  os- 


270  INORGANIC  CHEMISTRY. 

mium,  lead,  tin,  and  a  little  alkali  combined  with  silicic  acid  and  water.    In  making 
the  analysis  of  this  mineral,  Berzelius  discovered  thorina. 

1456.  From  chloride  of  thorium,  as  from  the  other  chlorides  of  the  same  metallic 
genus,  the  radical  may  be  evolved  by  means  of  potassium  and  heat.     It  may  like- 
wise be  extricated  from  the  double  fluoride  of  thorium  and  potassium,  or  fluothorate 
of  potassium.     Thorium,  in  its  appearance  and  in  many  of  its  properties,  much  re- 
sembles  aluminium  ;  but  differs  from  it  in  not  being  oxidized  by  reaction  with  boil- 
ing  water,  dilute  sulphuric  acid,  or  alkaline  solutions.     When  heated  gently  in  the 
air,  thorium  inflames,  and  is  converted  into  thorina. 

1457.  I  do  not  conceive  that  either  thorium,  or  any  other  of  those  substances  enu- 
merated as  convertible  by  oxidizement  into  the  earths  proper,  are  more  entitled  to  be 
considered  as  metals,  than  carbon  in  the  state  of  plumbago. 

Of  Thorina. 

1458.  Thorina  is  white,  tasteless,  and  inodorous.     In  common  with  alumina,  glu- 
cina,  and  yttria,  it  is  capable  of  acting  as  a  base  with  water.     The  resulting  hydrate 
of  thorina  is  by  heat  convertible  into  the  anhydrous  oxide,  in  a  state  of  great  hard- 
ness. 

1459.  Thorina  may  be  known  from  its  sulphate  being  more  soluble  in  cold  than  in 
hot  water.     It  is  composed  of  one  atom,  of  thorium,  equivalent  60,  and  one  atom  of 
oxygen,  equivalent  8  =  68. 


OF  METALS  OF  THE  ALKALINE  EARTHS. 

1460.  Under  this  head  are  included  magnesium,  calcium, 
barium,  and  strontium. 

SECTION  I. 

OF   MAGNESIUM. 

1461.  Magnesium  was  first  obtained  by  Bussy  in  1829, 
by  subjecting  the  chloride  to  the  action  of  potassium,  in  a 
manner  precisely  similar  to  that  already  described  for  ob- 
taining aluminium  (1422).     It  resembles  silver  in  colour 
and  fusibility.     It  is  malleable,  and  has  a  decided  metallic 
brilliancy.     It  is  oxidized  by  exposure  to  the  air,  or  to 
boiling  water.    When  sufficiently  heated  in  the  air,  it  com- 
bines with  oxygen,  and  is  converted  into  magnesia.     Its 
specific  gravity  is  greater  than  that  of  water. 

Of  Magnesia. 

1462.  This  earth  exists  abundantly  in  a  state  of  com- 
bination in  nature.    Dr.  Thomson  states  that  a  whole  range 
of  low  hills,  consisting  of  anhydrous  carbonate  of  mag- 
nesia, exist  in  India. 

1463.  Sulphate  of  magnesia  is  one  of  the  salts  which 
exist  in  the  ocean,  and,  consequently,  when  sea  water  is 
evaporated  in  order  to  obtain  common  salt,  the  sulphate 
may  be  obtained  from  the  mother-water.    For  the  manu- 


CALCIUM,  BARIUM,  AND  STRONTIUM.  271 

facture  of  the  salt  first  abovementioned,  magnesia  has  been 
largely  obtained  in  this  country,  from  an  American  mineral 
called  magnesite,  which  is  silicate  of  magnesia,  iron,  and 
lime.  Many  varieties  of  lime-stone  and  marble  contain 
magnesia.  The  marble  called  dolomite,  is  especially  well 
known  as  a  compound  of  lime  and  magnesia.  The  pre- 
sence of  magnesia  renders  a  carbonate  less  ready  to  give 
out  carbonic  acid  gas. 

1464.  This  earth  may  be  precipitated  from  a  solution  of 
Epsom  salt,  by  adding  a  solution  of  potash  or  soda.     It 
may  likewise  be  obtained  from  the  carbonate  by  heat. 

1465.  Properties. — Magnesia  is  white,  has  a  feeble  alka- 
line taste,   and  affects  vegetable  colours  like  an  alkali, 
though  feebly.  (1070.)    It  is  nearly  insoluble  in  pure  water, 
but  dissolves  to  a  considerable  extent  in  water  containing 
carbonic  acid,  forming  a  soluble  supercarbonate. 

1466.  Magnesia  is  distinguished  from  the  other  alkaline 
earths,  not  only  by  being  less  energetic  in  its  affinities 
and  alkaline  properties,  but  by  the  solubility  of  its  sul- 
phate. 

1467.  Magnesia  is  one  of  the  most  fixed  and  refractory 
substances  in  nature,  and  was  deemed  infusible  until  fused 
by  me  in  1801,  with  the  aid  of  the  compound  blowpipe. 
The  specific  gravity  of  magnesia  is  2.3,  and  its  equiva- 
lent, 20. 

Experimental  Illustrations. 

1468.  The  precipitation  of  magnesia  from  a  solution  of 
Epsom   salt;   exhibited;   also  its   effects   upon   vegetable 
colours. 


SECTION  II. 

OF  CALCIUM,  BARIUM,  AND  STRONTIUM,  THE  METALS  OF 
THE  THREE  PRE-EMINENTLY-,  ALKALINE  EARTHS. 

1469.  These  metals  are  so  much  alike  in  their  habi- 
tudes, that  I  deem  it  expedient  to  treat  of  them  under  one 
head.  Their  oxides  constitute  three  of  the  four  earths 
distinguished  as  alkaline,  which  are  pre-eminent  in  alka- 
linity. (1070.)  Next  to  oxygen,  silicon,  and  aluminium, 


272  INORGANIC  CHEMISTRY. 

calcium  is  probably  the  most  abundant  element  in  the  crea- 
tion. Barium  is  comparatively  a  rare  product,  and  stron- 
tium, as  an  ingredient  in  our  globe,  is  still  more  sparsely 
distributed  than  barium.  Neither  exists  excepting  in  com- 
bination, and  for  the  most  part  in  the  state  of  oxide,  in 
union  with  an  inorganic  acid,  especially  carbonic  and  sul- 
phuric acid. 

Of  the  Evolution  of  Calcium,  Barium,  and  Strontium. 

1470.  In  the  last  edition  of  this  Compendium,  it  was 
mentioned,  upon  the  authority  of  some  of  the  most  ap- 
proved  treatises   of  chemistry,    that   Davy  had   isolated 
calcium.     During  the  winter  of  1838,  being  engaged  in 
some  efforts  for  obtaining  the  metal  abovementioned,  I 
was  induced  to  re-peruse  the  original  lecture  in  which  the 
distinguished  chemist  above  named  described  the  result  of 
his  attempts  to  isolate  the  metals  in  question. 

1471.  It  should  be  known,  that  by  Seebeck,  and  by  Ber- 
zelius,  and  Pontin,  amalgams  had  been  obtained  of  cal- 
cium, barium,  and  strontium.     From  the  amalgams  thus 
discovered,  Davy  undertook  to  distil  the  mercury ;  but  he 
frankly  declared  that  he  was  in  nowise  certain  that  he 
had  succeeded  in  this  object.     In  the  case  of  calcium,  in 
his  "most  successful"  experiment,  "the  tube  broke  and  the 
metal  took  fire"  before  the  process  was  completed.     Sub- 
sequently to  the  date  of  these  facts,  as  far  as  I  have  been 
enabled  to  learn,  neither  Davy  nor  any  other  manipulator 
has  succeeded  in  making  a  less  abortive  experiment  than 
that  in  which  he  was  most  successful.     This-  justifies  the 
idea,  that  there  has  been  some  inherent  difficulty  which 
could  not  be  overcome  by  the  means  to  which  he  resorted. 
Agreeably  to  my  experience,  the  weight  of  sixty  grains  of 
mercury,  which  is  the  quantity  which  he  alleges  himself  to 
have  employed,  cannot,  by  the  most  powerful  apparatus, 
be  made  to  take  up  a  sufficiency  of  calcium  to  leave  a 
perceptible  quantity  of  this  metal  when  the  mercury  is  dis- 
tilled from  the  aggregate.     And  I  fully  concur  with  Davy 
in  the  opinion,  that  the  temperature  requisite  to    drive 
mercury  from  an  amalgam,  either  of  calcium,  of  barium, 
or  of  strontium,  is  higher  than  glass  will  bear.* 

*  To  enable  the  reader  to  judge  of  the  justice  of  my  remarks  respecting  the  claims 
advanced  by  Davy,  I  will  here  quote  his  own  language. 

"  That  to  obtain  a  complete  decomposition  was  extremely  difficult,  since  nearly  a 


LIME,  OR  CALCIA,  THE  OXIDE  OF  CALCIUM.  273 

1472.  Having  in  my  treatise  on  galvanism,  or  voltaic 
electricity,  given  an  engraving  and  description  of  my  ap- 
paratus, and  an  account  of  rny  process  for  the  evolution  of 
the  metals  in  question,  I  shall  here  only  quote  a  few  words 
respecting  their  properties  as  observed  by  me. 

1473.  "  Either  metal  was  rapidly  oxidized  in  water,  or 
in  any  liquid  containing  it;  and  afterwards,  with   tests, 
gave  the  appropriate  proofs  of  its  presence.      They  all 
sank  in  sulphuric  acid ;  were  all  brittle  and  fixed ;  and,  for 
fusion,    required  at  least  a  good  red-heat.     After  being 
kept  in  naphtha,  their  effervescence  with  water  was,  on  the 
first  immersion,  much  less  active.     Under  such  circum- 
stances they  reacted,  at  first,  more  vivaciously  with  hydric 
ether  than  with  water,  or  even  chlorohydric  acid ;  because 
in  these  liquids  a  resinous  covering,  derived  from  the  naph- 
tha, was  not  soluble,  while  to  the  ether  it  yielded  readily." 


SECTION  III. 

OF  LIME,  OR  CALCIA,  THE  OXIDE  OF  CALCIUM. 

1474.  This  oxide  exists  largely  in  nature  in  combina- 
tion with  carbonic  acid,  forming  all  the  varieties  of  marble 
and  limestone.  Some  kinds  of  white  marble,  especially 
that  of  Carrara,  so  celebrated  on  account  of  its  employ- 
ment in  statuary,  consist  solely  of  this  earth  combined 
with  water  and  carbonic  acid,  uncontaminated  by  any 

red-heat  was  required,  and  that  at  a  red-heat  the  bases  of  the  earths  acted  upon  the 
glass,  and  became  oxygenated.  When  the  tube  was  large  in  proportion  to  the  quan- 
tity of  amalgam,  the  vapour  of  naphtha  furnished  oxygen  sufficient  to  destroy  a 
part  of  the  bases  ;  and  when  a  small  tube  was  employed,  it  was  difficult  to  heat  the 
part  used  as  a  retort  sufficiently  to  drive  the  whole  of  the  mercury  from  the  base 
without  raising  too  highly  the  temperature  of  the  part  serving  for  a  receiver  so  as 
to  burst  the  tube."  "  When  the  quantity  of  amalgam  was  about  fifty  or  sixty  grains, 
I  found  that  the  tube  could  not  be  conveniently  less  than  one-sixth  of  an  inch  in 
diameter,  and  of  the  capacity  of  about  half  a  cubic  inch.  In  consequence  of  these 
difficulties,  in  a  multitude  of  trials  I  had  few  successful  results;  and  in  no  case 
could  I  be  absolutely  certain  that  there  was  not  a  minute  portion  of  mercury  still  in 
combination  with  the  metals  of  the  earths."* 

In  a  subsequent  paragraph  the  distinguished  lecturer  adds :  "  The  metal  from 
lime  I  have  never  been  able  to  examine  exposed  to  air  or  under  naphtha.  In  the 
case  in  which  I  was  enabled  to  distil  the  mercury  from  it  to  the  greatest  extent,  the 
tube  unfortunately  broke  while  warm,  and  at  the  same  moment  when  the  air  en- 
tered, the  metal,  which  had  the  colour  of  silver,  took  fire  and  burnt,  with  an  intense 
white  light,  into  quicklime."* 

*  See  Nicholson's  Journal,  Vol.  XXI.  for  1808;  or,  Tilloch's  Philosophical  Maga- 
zine, Vol.  XXXIII. 
35 


274  INORGANIC    CHEMISTRY. 

other  matter.  Hence,  if  the  acid  and  water  be  expelled 
by  heat,  the  lime  will  remain  in  a  state  of  purity.  Oyster- 
shells  yield  very  pure  lime  by  heating  them  to  incan- 
descence. 

1475.  When  impure  carbonates  of  lime  are  exposed  to 
a  very  high  temperature,  the  matter  constituting  the  impu- 
rities is  prone  to  enter  into  intimate  combination  with  the 
lime,  impairing  its  causticity,  and   susceptibility  of  the 
slaking  process.     No  doubt  this  arises  from  a  diminution 
of  affinity  for  water.    The  lime  of  shells  is  sometimes  par- 
tially converted  into  a  sulphide,  by  sulphur  derived  from 
the  animal  matter. 

1476.  The  calcination  requires  more  heat  in  a  crucible, 
especially  if  covered,  than  in  an  open  fire;  and  if  the  heat 
be  too  sudden,  the  carbonate  may  be  fused  without  the 
expulsion  of  all  the  acid,  which  is  afterwards  more  tena- 
ciously retained.     The  extrication  of  the  carbonic  acid  is 
promoted  by  a  current  of  steam,  or  of  any  other  aeriform 
fluid.     But  steam  is  preferable,  as  it  is  more  easily  pro- 
cured, and  cannot  be  productive  of  impurity.     The  ra- 
tionale is,  that  homogeneous  aeriform  particles  interfere 
with  each  other  more  than  heterogeneous,  which,  agree- 
ably to  the  Daltonian  doctrine,  to  a  certain  extent  oppose 
no  resistance  to  reciprocal  intermixture  arid  penetration. 

1477.  After  the  first  calcination,  Berzelius  recommends 
that  the  lime  be  slaked,  and  again  calcined  in  an  open 
crucible. 

1478.  Properties. — The  colour,  taste,  and  smell  of  this 
earth,  are  well  exemplified  in  the  best  kinds  of  lime  used 
in  building  (sometimes  called  quicklime),  which  is,  strictly 
speaking,  oxide  of  calcium,  isolated  from  the  water  and 
carbonic  acid  usually  united  with  it  as  found  in  nature. 

1479.  Quicklime  has  the  property  of  combining,  as  a 
base,  with  water,  acting  as  an  acid.  (826.)    The  water  be- 
coming, in  consequence,  consolidated,  abandons  its  latent 
heat,  or  caloric  of  fluidity.     Hence  great  sensible  heat  is 
excited,  and  when  the  mass  undergoing  the  change  is 
large,  ignition  occasionally  ensues.     The  lime  is  by  these 
changes  rendered  pulverulent,  and  is  said  to  be  slaked. 
The  process  is  called  slaking.     The  slaked  lime  thus  pro- 
duced, is  by  chemists  called  hydrate  of  lirrfe.  (826.)    Quick- 
lime is  productive  of  heat,  even  when  triturated  with  snow. 

1480.  Water  takes  up  about  Teeth  of  its  weight  of  this 


LIME,  OR  CALCIA,  THE  OXIDE  OP  CALCIUM.  275 

earth,  forming  lime-water.  On  this  a  pellicle  is  generated, 
soon  after  exposure  to  the  air,  by  the  union  of  the  lime 
with  the  carbonic  acid,  which  always  exists  in  the  atmo- 
sphere. 

1481.  In  lime-water,  some  metallic  oxides  are  soluble, 
especially  those  of  lead  and  mercury.    It  follows,  from  the 
definition  of  acidity  and  basidity,  that  in  the  resulting  com- 
pounds, the  oxides  of  the  metals  proper  act  as  acids,  while 
that  of  calcium  acts  the  part  of  a  base.  (629,  &c.)    The 
property  which  lime  has  of  affecting  vegetable  colours, 
like   an   alkali,   has   already  been   noticed.   (1065,  &c.) 
Though  lime  is  precipitated  from  the  aqueous  solution, 
known  as  lime-water,  by  carbonic  acid,  yet  an  excess  of 
this  acid  being  supplied,  the  precipitate  is  re-dissolved.    It 
is  in  this  way,  no  doubt,  that  the  water  in  limestone  coun- 
tries becomes  charged  with  this  earth. 

1482.  The  hardening  of  mortar  is  ascribed  by  Berzelius 
to  the  affinity  between  the  lime  and  the  silicic  acid  in  the 
sand.     Hence  the  necessity  of  this  ingredient. 

Experimental  Illustrations. 

1483.  Characteristic  changes  produced  in  vegetable  co- 
lours by  the  solution  of  the  earth  in  water,  called  lime- 
water.     A  glass  of  lime-water  is  not  made  turbid  by  air 
from  a  bellows,  but  becomes  so  on  propelling  the  breath 
through  it.     Absorption  of  carbonic  acid  by  lime-water, 
shown.     Solution  of  lime  by  an  excess  of  the  acid.     Lime 
precipitated  from  solutions  of  its  muriate  or  nitrate,  by 
sulphuric  or  oxalic  acid. 

Of  Peroxide  or  Bioxide  of  Calcium. 

1484.  Oxygen  is  absorbed  when  passed  over  lime  heated 
to  incandescence.     By  adding  lime-water  to  oxygenated 
water,  acidulated  with  muriatic  acid,  Thenard  procured 
crystals  of  bioxide  of  calcium.  (853,  &c.) 

Of  Baryta. 

1485.  This  earth  was  named  from  the  Greek  B*^?,  heavy; 
because  the  minerals  containing  it  are  peculiarly  heavy, 
when  compared  with  other  earthy  substances. 


276  INORGANIC  CHEMISTRY. 

1486.  Preparation. — To  procure  baryta,  eight  parts  of 
the  sulphate,  finely  pulverized,  should  be  intimately  min- 
gled with  one  of  charcoal,  and  afterwards  triturated  with 
two  parts  of  resin,  sugar,  molasses,  or  wheat  flour.     The 
mixture  is  to  be  kept  at  a  white  heat,  in  a  Hessian  cruci- 
ble, for  three-quarters  of  an  hour. 

1487.  The  sulphate  of  baryta,  by  being  deprived  of  oxy- 
gen, becomes  converted  into  a  sulphuret  of  barium,  which 
yields  a  nitrate  of  baryta  on  the  addition  of  nitric  acid. 
The  filtered  solution  by  evaporation  yields  crystals  of  the 
nitrate,  which  should  be  decomposed  in  a  porcelain  or  pla- 
tinum crucible.     This  operation  is  tedious;  since  the  heat 
cannot  be  urged  beyond  a  certain  degree  of  intensity, 
without  causing  the  salt  to  rise  up  in  a  foam,  so  as  to 
overflow  the  crucible.    If  the  heat  be  arrested  at  a  certain 
stage  of  the  process,  Berzelius  alleges  that  a  portion  of  ni- 
trous oxide  remains  united  with  the  earth,  forming  a  com- 
pound which  has  been  mistaken  for  bioxide  ("  suroxide") 
of  barium. 

1488.  Neither  the  carbonates  nor  hydrates  of  baryta,  or 
of  strontia  are,  like  those  of  lime,  decomposable  per  se  by 
heat.     The  addition  of  carbonaceous  matter  enables  us 
to  decompose  them;  as  it  changes  the  carbonic  acid  into 
carbonic  oxide,  which  has  no  affinity  for  the  earths,  and, 
therefore,  escapes. 

1489.  Properties. — Baryta  is  acrid,  slakes  like  lime,  and 
is  more   soluble  in  water.     It  is  more  actively  alkaline, 
both  as  respects  its  taste  and  its  action  on  vegetable  co- 
lours, than  any  other  earth.     It  is  gray  at  first,  but  ab- 
sorbs water  and  becomes  white.     Its  aqueous  solution  is 
rendered  milky  by  carbonic  acid,  and,  by  combining  with 
it,  becomes  covered  with  a  pellicle  of  carbonate,  when  ex- 
posed to  the  atmosphere.     From  its  solution  in  boiling 
water,  baryta  crystallizes  on  cooling. 

1490.  Solutions  of  barium,  whether  in  the  state  of  a 
hydrate,  acetate,  nitrate,  or  chloride,  are  very  useful  as 
tests  for  sulphuric  acid,  which,  combining  with  the  oxide  of 
barium  (baryta),  previously  existing  in  the  hydrate  or  ni- 
trate, or  formed  from  the  chloride  by  the  decomposition  of 
water,  is  precipitated  by  them  from  any  liquid. 

1491.  Ignited  intensely,  it  absorbs  oxygen  if  exposed  to 
it,  and  passes  to  the  state  of  bioxide.  This  earth  is  poison- 


LIME,  OR  CALCIA,  THE  OXIDE  OF  CALCIUM.  277 

ous.     Its  specific  gravity  is  4,  and  its  equivalent,  formed 
of  one  atom  of  barium  =  69,  and  one  of  oxygen  =  8 

=  77. 

Experimental  Illustrations. 

1492.  Baryta,  free  from  water,  exhibited;  also  in  crys- 
tals,    Barytic  water  rendered  milky  by  the  carbonic  acid 
of  the  breath.     Solutions  of  baryta,  and  of  sulphuric  acid, 
introduced  into  distinct  vessels  of  pure  water,  have  no 
effect;  but  portions  mingled  in  the  same  vessel  produce 
a   cloud.     Water,   coloured   by  alkanet,    turmeric,    &c., 
changed  by  baryta,  as  by  an  alkali. 

Of  Strontia. 

1493.  This  earth  is  very  analogous  to  baryta  in  its  pro- 
perties and  composition.     It  is  distinguished  from  baryta, 
by  the  red  colour  which  its  solutions  communicate  to  flame, 
by  its  crystallization,  and  by  its  being  more  soluble  in  boil- 
ing water  and  less  so  in  cold.     Excepting  baryta,  it  is 
more  actively  alkaline  than  any  other  earth,  both  as  re- 
spects taste  and  its  action  on  vegetable  colours. 

1494.  Strontia  water  is  not  like  that  of  baryta  precipi- 
tated by  a  dilute  solution  of  the  sulphate  of  potash,  or 
that  of  soda,  and  when  added  to  a  solution  of  bichromate 
of  lead  its  power  as  a  precipitant  is  inferior. 

1495.  Strontia  maybe  obtained  from  the  carbonate  or 
sulphate,  by  a  process  in  every  respect  similar  to  that 
which  has  been  described  as  the  means  of  procuring  ba- 
ryta. 

1496.  The  equivalent  of  this  earth  is  52. 

Experimental  Illustrations. 

1497.  Turmeric,  alkanet,  and  red  cabbage,  changed  by 
strontia-water,  as  by  alkalies.     Red  colour  of  the  flame  of 
alcohol,  containing  strontia,  shown.     Effects  of  the  aque- 
ous solutions  of  the  alkaline  earths  on  a  solution  of  bichro- 
mate of  lead. 

Of  the  Peroxides  or  Bioxides  of  Barium  and  Strontium. 

1498.  When  the  protoxides  of  barium  and  strontium 


278  INORGANIC  CHEMISTRY. 

are  heated  in  contact  with  oxygen  gas,  they  absorb  it,  and 
are  converted  into  bioxides.  When  an  aqueous  solution 
of  these  earths  is  added  to  oxygenated  water,  the  bi- 
oxides of  their  metallic  radicals  are  precipitated  in  a  crys- 
talline form. 

1499.  It  was  by  means  of  a  bioxide  of  barium  thus  pro- 
cured, that  Thenard  was  enabled  to  obtain  oxygenated 
water.  (853.)     The  bioxide  of  barium  was   dissolved  in 
chlorohydric  acid.     By  adding  sulphuric  acid,  sulphate  of 
baryta  was  precipitated,  in  which  half  of  the  oxygen  of  the 
bioxide  was  retained,  the  other  half  being  left  in  combina- 
tion with  the  water  of  the  solvent.     This  operation  being 
repeated  several  times,  the  liquid  became  more  and  more 
surcharged  with  oxygen.     Afterwards,  the  chlorine  of  the 
acid  was  precipitated  by  sulphate  of  silver,  and  the  sul- 
phuric acid,  thus  introduced,  by  baryta.     Finally,  the  bi- 
oxide being  less  susceptible  of  vaporization  than  water, 
this  liquid  was  removed  by  evaporation  in  vacuo  over  sul- 
phuric acidi  (399.)    Thus  isolated,  the  oxygenated  water 
was  ascertained  to  deserve  the  appellation  of  bioxide,  being 
found  to  hold  two  equivalents  of  oxygen  for  one  of  hy- 
drogen. 

OF  THE  METALS   OF  THE  FIXED  ALKALIES,  OR  ALKALIFI- 
ABLE  METALS,  POTASSIUM,  SODIUM,  AND  LITHIUM. 

SECTION  I. 

OF   POTASSIUM. 

1500.  The   discovery  of  potassium   and   sodium  was 
made  by  Sir  Humphry  Davy,  in  1807,  by  exposing  their 
oxides,  potash,  and  soda,  to  the  divellent  influence  of  the 
Voltaic  current.     These  metals  were  afterwards  obtained 
more  copiously,  by  subjecting  the  alkalies,  in  contact  with 
iron  in  a  divided  state,  to  intense  heat  in  a  luted  gun  bar- 
rel.    Latterly,  they  have  been  obtained,  with  still  greater 
facility,  by  heating  the  carbonates  intensely,  while  inter- 
mingled with  charcoal.* 

*  In  Brunner's  process,  bitartrate  of  potash,  or  carbonized  cream  of  tartar,  which 
consists  of  carbonate  of  potash  intimately  intermingled  with  the  residual  carbon  of  the 
decomposed  tartaric  acid,  is  subjected  to  intense  heat  in  a  luted  iron  mercury  bottle, 
some  coarsely  powdered  charcoal  being  added.  The  potassium  was  conveyed  into 
a  copper  vessel  containing  naphtha  as  it  came  over  from  the  bottle.  For  this  vessel, 
I  have  substituted  an  iron  tube,  which  becomes  finally  full  of  the  metal  and  a  carbo- 


POTASSIUM. 


279 


1501.  The  alkaline  metal,  whether  potassium  or  sodium, 
being  volatile  at  any  temperature  above  redness,  is  extri- 
cated in  the  state  of  vapour,  and  condensed  in  a  part  of 
the  apparatus  where  the  heat  is  below  redness. 

1502.  Properties.  —  Potassium,  when  newly  cut,  strongly 
resembles  silver  in  appearance.     It  is  malleable,  and  so 
soft  at  ordinary  temperatures,  as  to  be  moulded  between 
the  fingers  like  wax.     When  cooled  to  32%  it  becomes 
brittle,  and  exhibits,  when  broken,  a  crystalline  fracture. 
It  melts  at  106°,  and  is  converted  into  vapour  when  heated 
to  a  little  below  redness.    When  exposed  to  the  air  at  the 
ordinary  temperature,  it  absorbs  oxygen  rapidly,  and  is 
converted  into  potash.     This  absorption  is  sometimes  so 
active,  especially  when  aided  by  friction,  as  to  cause  the 
inflammation  of  the  potassium.     I  once  lost  half  an  ounce 
of  potassium,  in  consequence  of  attempting  to  extricate  it 
by  dividing  the  containing  bottle  by  a  file;  it  took  fire,  and 
was  entirely  oxidized.     The  affinity  of  this  metal  for  oxy- 
gen is  so  strong,  that,  when  thrown  upon  water  or  ice,  it 
combines  with  the  oxygen;  while  the  hydrogen  takes  up  a 
certain  portion  of  the  potassium,  and  burns  with  a  beauti- 
ful rose-coloured  flame.     Potassium  is  lighter  than  water, 
its  specific  gravity  being  only  0.86.     It  is  a  good  conduc- 
tor of  heat  and  electricity.     Its  atomic  weight  is  40. 


SECTION  II. 

OF  SODIUM. 

1503.  Properties.  —  Sodium  resembles  potassium  in  its 
appearance,  and  in  many  of  its  properties.     It  retains  its 

naceous  mass,  which  sublimes  during  the  operation.  The  tube  is  then  removed,  and 
the  end  nearest  the  bottle  screwed  into  a  tapering  tube,  while  the  other  orifice  is 
closed  by  a  cap,  into  which  it  fastens  by  screwing.  The  tube  is  then  placed  vertically 
in  a  furnace,  through  the  bottom  of  which  the  tapering  tube  extends  so  as  to  be  out 
of  the  way  of  the  heat.  Under  the  orifice  of  this  tube,  a  vessel  may  be  placed  con- 
taining some  naphtha,  to  receive  the  potassium  as  it  descends  in  globules,  after  fusion 
or  condensation  from  the  state  of  vapour.  The  last  portions  are  not  evolved  before 
the  fire  in  the  furnace  reaches  a  white  heat.  The  principal  source  of  disappoint- 
ment in  Brunners  process,  is  the  failure  of  the  luting.  When  this  happens,  the 
iron  bottle  is  soon  burnt  through.  I  have  found  it  advantageous  to  secure  the  iron 
bottle  employed  in  this  process,  while  supported  vertically  in  the  furnace,  by  a  stout 
cylinder  of  the  same  metal,  the  whole  resting  upon  an  iron  disk  supported  by  bricks 
made  of  porcelain  earth. 

By  these  means,  I  procured  last  winter,  at  one  operation,  more  than  six  ounces  of 
potassium, 


280  SODIUM. 

softness  and  malleability  when  cooled  to  32°.  A  globule 
of  sodium,  thrown  upon  water,  swims  to  and  fro  on  the 
surface  with  great  rapidity,  absorbing  oxygen,  and  evolv- 
ing hydrogen  from  the  water;  yet  no  inflammation  ensues. 
This  is  probably  owing  to  the  rapidity  of  its  motion, 
which,  by  bringing  it  in  contact  with  successive  portions 
of  water,  keeps  the  temperature  below  that  which  is  ne- 
cessary to  combustion ;  since,  when  the  water  is  thickened 
with  a  little  gum,  which  tends  to  impede  the  motion  of 
the  globule,  sodium  burns  with  a  brilliant  yellow  flame. 
The  presence  of  an  acid  produces  the  same  result.  The 
affinity  of  sodium  for  oxygen,  does  not  appear  to  be  so 
strong  as  that  of  potassium;  since,  according  to  Thenard, 
it  is  not  oxidized  when  exposed  to  dry  atmospheric  air,  or 
oxygen.  It  melts  at  194°,  and  for  volatilization,  requires 
a  higher  temperature  than  potassium. 

1504.  Sodium  forms  a  number  of  alloys  with  potassium; 
one  of  these  remains  fluid  at  32°,  and  is  lighter  than  naph- 
tha.    The  specific  gravity  of  sodium  is  0.97223.     It  is 
a  good  conductor  of  heat  and   electricity.     Its  atomic 
weight  is  24. 

Experimental  Illustrations. 

1505.  The  inflammation  of  potassium  and  sodium  upon 
water  and  ice,  exhibited;  also  the  regeneration  of  the 
alkali,  demonstrated  by  the  usual  tests.     The  decomposi- 
tion of  potash,  by  iron  card-teeth,  heated  to  incandescence. 
Apparatus  for  its  evolution,  exhibited. 

Of  Potash  or  Potassa,  and  Soda,  the  Protoxides  of 
Potassium  and  8 odium. 

1506.  A  ley,  obtained  by  the  lixiviation  of  the  ashes  of 
inland  plants,  especially  wood,  when  boiled  down,  yields 
the  potash  of  commerce.     Potashes  ignited  so  as  to  de- 
stroy vegetable  colouring  matter  and  other  impurities,  again 
dissolved,  and  boiled  to  dryness,  form  pearlash.     Pearlash, 
dissolved  in  water,  boiled  with  lime  to  remove  the  carbonic 
acid,  filtered,  and  boiled  down  to  the  consistency  of  moist 
sugar,  dissolved  in  alcohol,  and  boiled  down  gradually,  and, 
lastly,  fused  at  a  red-heat  in  a  silver  vessel,  forms  the  pot- 
ash, or,  more  strictly,  the  hydrate  of  potash  of  chemists. 
If,  as  soon  as  the  alcohol  has  escaped,  the  residual  mass 


SODIUM.  281 

be  refrigerated,  it  crystallizes.  After  fusion  at  a  red-heat, 
the  alkali  contains  about  20  per  cent,  of  water,  existing  in 
it  as  an  acid,  and  of  which,  per  se,  it  cannot  be  deprived 
by  heat. 

1507.  Pure  carbonate  of  potash  may  be  procured  from 
bitartrate  of  potash,  whether  carbonized  by  heat,  or  defla- 
grated with  pure  nitre,  by  subjecting  the  residue  to  water, 
and  the  resulting  solution  to  heat,  to  vaporize  the  solvent. 

1508.  To  obtain  pure  potash,  or  in  other  words,  to  re- 
move carbonic  acid  from  the  alkali  of  a  carbonate,  Berzelius 
advises  the  addition  of  one  and  a  half  parts,  by  weight,  of 
pure  hydrate  of  lime,  to  one  part  of  a  pure  carbonate,  ob- 
tained as  abovementionedvdissolved  in  a  cauldron,  and  kept 
boiling.     The  lime  is  not  to  be  added  at  once,  but  gra- 
dually; as  without  this  precaution,  the  resulting  carbonate 
of  lime  retains,  like  a  sponge,  a  great  part  of  the  alkali. 
The  liquid  is  to  be  tested  by  an  acid  or  by  lime-water, 
until  it  ceases  to  indicate  the  presence  of  carbonic  acid. 
After  this,  it  may  either  be  kept  in  a  liquid  state,  or  evapo- 
rated till  it  crystallizes,  and  preserved  in  crystals ;  or  being 
ignited  till  it  becomes  fused,  and  poured  out  on  a  slab,  or 
into  moulds,  it  may  be  preserved  in  the  state  of  hydrate. 

1509.  I  have  used  for  the  purpose  last  mentioned,  the 
moulds  usually  employed  for  casting  musket  balls.     The 
spherical  form  presenting  the  least  surface  in  proportion 
to  the  mass,  is  favourable  to  the  preservation  of  a  sub- 
stance liable  to  be  deteriorated  by  contact  with  the  atmos- 
phere. 

1510.  The  crystals  of  potash,  thus  procured,  are  always 
free  from  carbonic  acid,  and  if  derived  from  a  pure  carbo- 
nate, excepting  water,  may  constitute  pure  potash.     But 
when  pearlash  is  the  carbonate  employed,  alcohol  must  be 
resorted  to,  after  the  caustic  ley  has  been  evaporated  to 
the  consistency  of  moist  sugar,  in  order  to  get  rid  of  the 
impurities.      This  liquid  combines  with  the  pure  potash, 
while  a  portion  of  water  contained  in,  or  formed  from,  the 
alcohol,  separates  from  it  in  union  with  the  impurities. 

1511.  Soda  is  obtained  from  the  ashes  of  certain  plants 
which  grow  on  the  sea-shore,  as  potash  is  by  the  incinera- 
tion of  those  which  grow  inland.     It  is  procured  also  from 
chloride  of  sodium,  and  sulphate  of  soda. 

1512.  Soda  is  purified,  and  procured  in  the  state  of  hy- 

36 


282  INORGANIC    CHEMISTRY. 

drate,  or  in  crystals,  by  a  process  analogous  to  that  above 
described  for  its  kindred  alkali. 

1513.  Properties  of  Potash  and  Soda. — Potash  and  soda 
are  of  a  grayish-white  colour,  and,  in  common  with  other 
alkalies,  have  a  peculiar  taste.     They  render  tincture  of 
turmeric  brown,  syrup  of  violets  green,  and  alkanet  blue. 
Colours  changed  by  acids,  are  restored  by  them.     They 
are  the  opposites  of,  and  antidotes  to,  acids,  and  capable  of 
forming  with  them  neutral  compounds,  or,  in  other  words, 
such  as  are  neither  acid  or  alkaline.     They  are  incor- 
rectly said  to  render  vegetable  blues  green,  as  if  this  were 
universally  true.      Alkanet  is  made  blue  by  them,  while 
neither  litmus  nor  indigo  is  rendered  green.  (1065,  &c.) 

1514.  Although  potash  is  more  soluble  than  soda,  and 
is  deliquescent,  while  soda  effloresces;   yet  the   salts  of 
soda  are  more  soluble  than  those  of  potash.     Both  cau- 
terize the  flesh.     Potash  is   the  more  active.     Common 
caustic  is  an  impure  hydrate  of  this  alkali. 

1515.  Crystallized  potash  contains  four  atoms  of  water 
to  one  of  the  oxide,  of  which  three  only  can  be  expelled  by 
heat.     After  fusion  it  may  be  called,  however  paradoxical 
it  may  seem,  an  anhydrous  hydrate,  though  not  an  anhy- 
drous oxide.     Both  potash  and  soda  fuse  when  subjected 
to  a  red-heat.     The  atomic  weight  of  potash  is  48,  that  of 
soda,  32.     The  hydrate  of  potash  consists  of  one  atom  of 
alkali,  and  one  of  water. 

1516.  Potash  may  be  distinguished   from  soda,  by  its 
forming  salts  nearly  insoluble  in  water  with  tartaric,  or 
oxychloric  acid ;  while  those  formed  by  soda  with  the  same 
acids  are  soluble.      Chloroplatinic  acid   causes  a  yellow 
precipitate  with  potash,  but  not  with  soda. 

Experimental  Illustrations* 

1517.  Characteristic  changes  produced  in  vegetable  infu- 
sions, as  in  previous  illustrations.  (1075.) 

1518.  To  a  saturated  solution  of  potash  and  soda,  or 
their  carbonates,  a  saturated  solution  of  tartaric  acid  being 
added  in  excess,  crystals  are  yielded  by  the  potash  only. 
Into  different  salts  of  the  two  alkalies  in  solution,  chioro- 
platinic  acid  being  poured,  a  yellow  precipitate  distinguishes 
the  potash. 


SODIUM.  283 


Of  the  Peroxides  and  Suloxidcs  of  Potassium  and  Sodium. 

1519.  Peroxide  of  potassium  is  produced  by  the  combustion  of  potassium  on  a 
plate  of  silver  in  oxygen  gas,  in  which  case  the  metal  acquires  three  times  as  much 
oxygen  as  it  holds  in  the  state  of  potash.     The  peroxide  is  also  obtained  when  nitre 
is  intensely  heated,  or  when  potassium  is  deflagrated  with  nitre. 

1520.  Two  parts  of  sulphate  of  potash,  ignited  intensely  with  one  of  lampblack, 
give  a  pyrophorus  which  takes  fire  spontaneously  with  scintillations  in  the  air.  This 
arises,  no  doubt,  from  the  extreme  state  of  division  in  which  carbon,  potassium,  and 
sulphur  exist  in  the  residual  mass. 

1521.  The  peroxide  of  potassium  is  of  a  greenish-yellow  colour,  and  possesses 
most  of  the  properties  of  the  protoxide,  excepting  that  of  acting  as  a  base.     When 
brought  in  contact  with  water  or  acids,  it  is  decomposed  into  potash  and  oxygen. 

1522.  The  peroxide  of  sodium  is  of  a  greenish-yellow  colour  also,  and,  in  its  pro- 
perties, is  analogous  to  the  peroxide  of  potassium,  except  that  at  a  high  temperature 
it  abandons  part  of  its  oxygen,  and  is  converted  into  protoxide.     It  cannot,  there- 
fore, be  obtained  by  burning  sodium  in  an  excess  of  oxygen;  since  the  heat  produced 
by  the  combustion,  would  decompose  the  peroxide,  if  already  formed.     In  order  to 
procure  it,  it  is  necessary  to  heat  soda  in  contact  with  oxygen.     The  peroxide  of  so- 
dium contains  one  and  a  half  atoms  of  oxygen,  united  to  one  of  metal. 

1523.  Berzelius  mentions  that-suboxide  of  potassium  may  be  obtained  by  heating 
the  metal  in  a  quantity  of  oxygen  inadequate  for  its  saturation;  also  by  exposing  to  a 
temperature  of  about  40°  F.,  a  mixture  of  hydrate  of  potash  and  potassium,  in  equi- 
valent proportions;  in  which  case  the  metal  is  oxidized  at  the  expense  of  the  com- 
bined water,  the  hydrogen  escaping.     The  anhydrous  protoxide  may  be  obtained  in 
like  manner,  by  heating  potassium  with  a  greater  quantity  of  the  hydrate.     Turner 
alleges,  however,  that  the  suboxide  of  potassium  is  generally  regarded  by  chemists 
as  nothing  more  than  a  mixture  of  potassium  and  potash. 

1524.  According  to  Berzelius,  a  suboxide  of  sodium  may  be  obtained  by  the  same 
means  as  the  suboxide  of  potassium,  substituting  the  one  metal  for  the  other.     The 
same  uncertainty,  however,  prevails  with  regard  to  it,  as  with  regard  to  the  suboxide 
of  potassium. 

1525.  When  potassium  or  sodium  is  heated  in  ammonia,  it  combines  with  nitrogen 
and  liberates  hydrogen,  and  the  resulting  nituret  absorbs  ammonia;  so  that  we  have 
a  combination  of  two  binary  compounds  of  nitrogen,  which  may  possess,  to  a  small 
extent,  the  relation  of  acid  and  base.     There  are,  however,  no  phenomena  in  che- 
mistry which  are  more  anomalous  than  those  which  are  associated  with  the  produc- 
tion and  evolution  of  this  compound.     Nevertheless,  as  its  nature  is  unintelligible 
even  to  adepts,  I  shall  not  present  the  details  here. 

1526.  I  hinted,  when  entering  upon  the  subject  of  nitrogen,  that  it  would  be  seen 
in  the  sequel,  that  it  was  not  destitute  of  pretensions  to  a  place  in  the  basacigen 
class.     It  was  in  reference  to  the  phenomena  above  alluded  to,  that  I  made  that  re- 
mark. 

1527.  If  nitrogen  form  the  common  ingredient  in  two  compounds,  one  electro- 
negative, the  other  electro-positive,  which  combine  to  form  a  third,  it  fulfils  the  con- 
dition of  a  body  producing  both  an  acid  and  a  base,  and  is  of  course  a  basacigen 
body.     Yet  it  has  already  been  pointed  out  that  there  is  no  class,  of  which  some  of 
the  members  do  not  display  properties  which  might  cause  them  to  be  placed  in  ano- 
ther class. 

Of  Pfiosphurct  of  Potassium. 

1528.  Phosphorus  and  potassium,  heated  together  in  nitrogen  or  hydrogen  gas, 
combine  with  the  phenomena  of  combustion.  In  phosphuretted  hydrogen,  potassium 
burns,  combining  with  phosphorus,  and  liberating  the  hydrogen. 

1529.  This  phosphuret  decomposes  water,  but,  according  to  Berzelius,  the  gas 
evolved  does  not  inflame  spontaneously. 

Of  the  Compounds  of  Potassium  with  Carbon,  Boron,  and  Silicon. 

1530.  The  black  matter  which  remains  after  the  distillation  of  potassium,  as  ob- 
tained by  Brunner's  process,  is  alleged  by  Berzelius  to  be  a  pcrcarburet  of  potassium. 
When  moistened  it  inflames,  no  doubt  by  decomposing  water,  and  evolving  potassu- 
retted  hydrogen.     The  black  matter  which  obstructs  the  tube  used  in  the  evolution 
of  potassium  by  the  process  above  mentioned,  is  also  held  to  be  a  carburet.  (1501  ) 

1531.  These  carburets  I  have  found  useful  in  purifying  naphtha,  by  its  distillation 
with  them.     After  undergoing  this  ordeal,  potassium  may  be  kept  in  it  with  less  ap- 


284  INORGANIC  CHEMISTRY. 

pearance  of  reaction.  I  am  under  the  impression  that  the  carbon  which  remains  in 
the  iron  bottle,  is  imbued  with  potassium,  possibly  in  a  state  of  chemical  union. 
This  may  be  used  likewise  for  the  purification  of  naphtha. 

1532.  It  appears  that,  during  the  reduction  of  boric  acid  by  potassium,  a  loruret  is 
formed;  since  a  portion  of  the  mass  evolves  a  gas  on  being  moistened,  which  has 
not  the  smell  of  pure  hydrogen.     It  is  probably  boruretted  hydrogen. 

1533.  A  siliciuret  of  potassium  is  obtained  during  the  decomposition  of  fluosilicic 
acid  gas.     A  portion  of  the  liberated  silicon,  combining  with  potassium,  forms  the 
compound  in  question.     This,  on  being  moistened,  gives  off  hydrogen,  which  has  a 
peculiar  odour  resembling  that  of  phosphuretted  hydrogen.     The  analogy  between 
these  results  and  those  mentioned  in  reference  to  boron,  is  obvious. 


SECTION  III. 

OF   LITHIUM. 

1534.  A  fixed  alkali  was  discovered,  in  1818,  by  Mr.  Arfwedson,  to  exist 
in  small  proportion,  as  an  ingredient  in  a  mineral  called  petalite.     He  af- 
terwards discovered  it  in  two  other  minerals,  called  spodumene  and  lepido- 
lite.     Allusion  to  this  alkali,  and  the  origin  of  its  name,  was  made  under 
the  head  of  Ammonia.  (1081.) 

1535.  By  the  influence  of  the  Voltaic  pile,  decided  indications  have  been 
obtained  of  the  existence,  in  lithia,  of  a  metallic  radical.    To  this  the  name 
of  lithium  has  been  given.     Lithium  resembles  sodium  in  appearance.     Its 
atomic  weight  is  6. 

Of  Lithia. 

1536.  Lithia,  known  only  in  the  state  of  hydrate,  is  white,  caustic,  and 
has  all  the  attributes  of  an  alkali.     When  lithia,  whether  in  the  state  of 
carbonate  or  uncombined,  is  heated  in  contact  with  platinum,  the  metal  is  at- 
tacked, and  a  compound  is  formed,  which,  according  to  Thenard,  probably 
consists  of  the  oxide  of  platinum,  united  to  the  oxide  of  lithium,  and  must 
of  course  be  a  platinate  of  lithia.     Lithia  is  composed  of  one  atom  of 
lithium,  equivalent  6,  and  one  atom  of  oxygen,  equivalent  8  =  14. 

1537.  Lithia  is  less  soluble  in  water  or  alcohol  than  soda  or  potash.    Its 
carbonate  is  less  soluble  in  water  than  the  carbonates  of  those  alkalies. 
The  chloride  of  lithium  is  deliquescent,  and  soluble  in  alcohol,  the  phos- 
phate of  lithia  is  insoluble  in  water;  in  which  respects  these  compounds 
differ  from  the  corresponding  combinations,  formed  by  the  other  fixed  alka- 
lies, or  their  radicals. 

Of  the  Reaction  of  Chlorine,  Bromine,  Iodine,  Fluorine, 
and  Cyanogen,  with  the  Metals  of  the  Earths  and  Alka- 
lies. 

1538.  In  a  former  edition  of  this  work,  it  was  mentioned 
that  for  aluminium,  glucinium,  yttrium,  thorium,  and  mag- 
nesium, chlorine  has  not  sufficient  affinity  to  expel  the 
oxygen  from  their  oxides;  and  that  it  was  only  in  the 
state  of  oxide  that  they  could  be  subjected  to  the  gas. 


LITHIUM.  285 

It  has  been  already  stated,  that  Oersted  ingeniously  con- 
trived to  enable  chlorine  to  combine  with  aluminium,  by 
the  co-operating  affinity  of  intermingled  carbon  for  the 
oxygen  with  which,  in  the  state  of  earth,  this  metal  is 
united :  also,  that  a  similar  process  had  been  successfully 
employed  to  obtain  the  chlorides  of  glucinium,  yttrium, 
thorium,  and  magnesium.  The  most  important  considera- 
tion, associated  with  the  existence  of  these  chlorides,  is 
their  susceptibility  of  decomposition  by  potassium,  and  the 
consequent  isolation  of  their  metallic  radicals. 

1539.  When  the  oxides  of  calcium,  barium,  strontium, 
potassium,  sodium,  and  lithium  are  heated  in  chlorine,  these 
metals  are  converted  into  chlorides,  the  oxygen  being  dis- 
placed.    Potassium  and  sodium  burn  actively  in  chlorine, 
and  it  appears  probable  that  any  of  the  metals  of  the  al- 
kalies or  alkaline  earths  may,  with  heat,  if  not  without,  be 
directly  combined  with  any  of  the  halogen  bodies.     The 
same  combinations  may  be  obtained  in  the  wet  way  by 
complex  affinity,  on  presenting  their  oxides  to  the  acids 
formed  by  these  bodies  with  hydrogen. 

1540.  The  chlorides  of  the  metals  of  the  alkalies,  and 
of  the  alkaline  earths,  are  all  soluble,  and  some  of  them 
deliquescent.     When  in  solution,  they  contain  the  same 
elements  as  if  they  were  chlorohydrates  of  oxybases;  and 
are,  therefore,  considered  as  such  by  some  chemists. 

1541.  The  difference  between  a  chloride  in  solution  and 
such  a  chlorohydrate,  is  rendered  evident  by  setting  down 
the   ingredients  agreeably  to   both   suppositions,  as  fol- 
lows:— 

Chlorine,  hydrogen.  Oxygen,  metal. 


Chlorohydric  acid.  Oxide. 


Chlorohydrate. 

Oxygen,  hydrogen.  Chlorine,  metal. 

Water.  Chloride. 

~v  — 

Dissolved  Chloride. 


286  INORGANIC  CHEMISTRY. 

1542.  The  soluble  chlorides  produce  white  precipitates 
in  solutions  of  silver,  lead,  or  black  oxide  of  mercury. 
They  do  not  deflagrate  with  charcoal,  nor  do  they,  like 
sulphates,  after  being  heated  with  it,  yield  the  odour  of 
sulphuretted  hydrogen  on  being  moistened. 

1543.  The  soluble  chlorides  of  the  metals  of  the  alkaline 
earths  and  alkalies,  excepting  that  of  magnesium,  are,  by 
heat,  converted  into  anhydrous  chlorides,  easily  detected 
by  the  fumes  which  they  give  with  sulphuric  acid. 

1544.  Bromine,  like  chlorine,  when  heated  with  any  of 
the  fixed  alkalies,  or  alkaline  earths,  except  magnesia,  dis- 
places the  oxygen  and  combines  with  the  metallic  radical. 
Like  chlorine  also,  it  does  not,  per  se,  produce  this  effect 
either  with  magnesia  or  the  earths  proper. 

1545.  The  affinities  of  iodine  are,  in  most  cases,  less 
energetic  than  those  of  chlorine  or  bromine.     Potash  and 
soda  are  the  only  oxides  of  the  metals  of  the  earths  and 
alkalies,  from  which  iodine  can,  with  the  assistance  of 
heat,  expel  the  oxygen,    in  order  to  combine  with  their 
metals. 

1546.  The  bromides  and  iodides,  when  combined  with 
water,  may,  like  the  chlorides,  be  regarded  either  as  in  a 
state  of  solution,  or  as  bromohydrates  and  iodohydrates. 
The  bromides  may  be  recognised  by  the  red  vapours  which 
arise,  when  they  are  heated  in  a  tube  with  the  bisulphate 
of  potash.     Similar  vapours  would  be  given  out  by  the 
nitrites,  if  treated  in  the  same  way;  but  the  bromides  may 
be  distinguished  from  those  salts,  by  their  not  deflagrating 
when  thrown  on  incandescent  coals. 

1547.  An  iodide  may  be  detected  by  dropping  a  portion 
into  sulphuric  acid,  heated  nearly  to  the  point  of  ebullition. 
(738.)    By  these  means  iodine,  if  present,  will  be  made  ap- 
parent in  the  form  of  a  violet  vapour.     Iodine  is  also  dis- 
placed from  its  combinations  by  chlorine;  and,  when  these, 
previously  to  the  addition  of  chlorine,  are  mingled  with  a 
paste  made  of  starch,  a  blue  colour  is  produced.     It  is 
alleged  that  sea  salt  sometimes  contains  a  quantity  of 
iodine  adequate  to  produce  this  result. 

1548.  Berzelius  states  that,  when  potassium  is  heated  in 
cyanogen,  it  is  converted  into  a  cyanide;  also  that  the 
habitudes  of  sodium  are  in  this  respect  similar.     It  is  pro- 
bable that  the  same  result  would  ensue  with  all  the  metals 


LITHIUM.  287 

of  the  alkalies  and  alkaline  earths.  Cyanogen  is  usually 
generated  by  the  reaction  of  potash  with  animal  matter, 
which  deoxidizes  the  alkali,  and  at  the  same  time  furnishes 
to  it  the  elements  of  cyanogen,  which,  in  consequence, 
simultaneously  unite  with  each  other  and  with  the  metal, 
forming  a  cyanide  of  potassium. 

1549.  When  the  cyanoferrite  of  potassium  (ferroprus- 
siate  of  potash)  is  intensely  heated,  the  cyanoferric  acid  is 
decomposed.     The  cyanide  of  potassium  remains  mingled 
with  a  carburet  of  iron,  and  may  be  extricated  by  solution, 
filtration,  evaporation,  and  crystallization.     Subjecting  the 
cyanoferrite  of  sodium  to  a  similar  process,  the  cyanide  of 
sodium  may  be  obtained.  (1299,  &c.) 

1550.  The  cyanides  may  be  detected  by  their  power  of 
producing  a  blue  colour  with  solutions  of  the  peroxide  of 
iron;  also  by  evolving  the  odour  of  peach  blossoms,  when 
subjected  to  chlorohydric  acid. 

1551.  It  is  highly  probable  that  the  reaction  of  fluorine 
with  the  metals  of  the  earths  and  alkalies,  will  prove  to  be 
analogous  to  that  of  chlorine.     The  fluorides,  however, 
differ  much  from  the  chlorides  in  solubility.     Some  varie- 
ties of  the  fluoride  of  calcium  constitute  Derbyshire  spar, 
while  the  chloride  of  calcium  is  a  deliquescent  salt. 

1552.  The  presence  of  fluorine  in  a  mineral  may,  in  a 
majority  of  instances,  be  detected  by  the  following  process. 
Let  a  small  portion  of  it  be  pulverized,  and  subjected  to 
heat  with  about  twice  its  weight  of  concentrated  sulphuric 
acid,  in  a  leaden,  silver,  or  platinum  cup.     Let  this  cup  be 
covered  by  a  glass  plate,  coated  with  beeswax,  through 
which  some  letters  have  been  traced  so  as  to  denude  the 
vitreous  surface.     After  exposure  for  half  an  hour,  aided 
by  as  much  heat  as  can  be  used  without  melting  the  wax, 
the  glass  should  be  relieved  from  its  coating  and  examined. 
Then,  if  the  portions  of  the  vitreous  surface,  exposed  to 
the  fumes,  prove  to  be  so  corroded  as  to  render  the  cha- 
racters traced  through  the  wax  distinguishable,  the  pre- 
sence of  fluorine  may  be  inferred. 

1553.  Berzelius  informs  us  that  when  this  principle  is  in 
combination  with  silicon,  it  will  not  act  on  glass.     Hence 
he  advises  that  the  mineral,  suspected  of  containing  fluo- 
silicic  acid,  should  be  subjected  to  the  flame  of  the  blow- 
pipe, at  one  end  of  a  glass  tube,  of  which  both  ends  are 
open ;  so  that  the  fumes  produced  may  be  impelled  by  the 


288  INORGANIC  CHEMISTRY. 

blast  through  the  tube  from  one  orifice  towards  the  other. 
By  these  means,  milky  spots  will  appear  on  the  glass,  in 
consequence  of  the  condensation  of  water  containing  fluo- 
silicic  acid,  if  this  be  an  ingredient  in  the  mineral. 

Of  the  Reaction  of  Sulphur,  Selenium,  and  Tellurium,  with 
the  Metals  of  the  Earths  and  Alkalies. 

1554.  Sulphur  unites  with  all  the  metals  of  the  alkalies 
and  alkaline  earths,  so  far  as  the  experiment  has  been 
tried,  whether  presented  to  them  in  the  metallic  state,  or 
in  that  of  oxide.     Its  power  of  reducing  their  oxides  is 
greater  than  that  of  any  other  basacigen  body;  as  when 
present  in  excess,  it  acts  by  its  affinity  for  the  oxygen  and 
the  metal.  (523,  &c.)    The  affinity  of  the  halogen  bodies 
for  oxygen,  is  so  inferior  to  that  of  sulphur,  that  when 
oxygen  is  expelled  from  oxides  by  one  portion  of  them,  it 
does  not  combine  with  another,  however  great  the  excess 
in  which  they  may  be  present. 

1555.  Sulphides  (sulphurets)  are  also  formed  by  deoxi- 
dizing the  sulphates  by  carbon  or  hydrogen  with  the  aid 
of  heat,  (1436,  1437,)  by   boiling   in  water   equivalent 
weights  of  sulphur  and  the  earth  or  alkali  to  be  com- 
bined; or  by  passing  sulphydric  acid  into  water,  holding 
the  oxide  in  solution  or  suspension.     When  this  is  done 
under  favourable  circumstances,  the  metal  is  converted 
into  a  sulphobase  by  the  sulphur  of  one  portion  of  the 
acid ;  while  the  compound  thus  formed  unites  with  another 
portion  of  the  acid,  forming  a  sulphosalt,  denominated  a 
sulphydrate.    This  view  of  the  subject  we  owe  to  Berzelius, 
who  has  shown  that  sulphur,  selenium,  and  tellurium,  all 
have  the  property  of  forming  acids  with  one  set  of  radicals, 
and  bases  with  another;  and  that  the  sulphacids  and.  sul- 
phobases  thus  formed,  are  capable,  like  oxacids  and  oxy- 
bases,  of  forming  compounds  which  he  considers  as  sulpho- 
salts,  or  salts  in  which  sulphur  performs  a  part  analogous 
to  that  which  oxygen  performs  in  oxysalts,  such  as  the 
sulphate  or  nitrate  of  potash. 

1556.  Formerly  it  was  supposed  that,  when  absorbed  by 
an  alkaline  solution,  sulphydric  acid  (sulphuretted  hydro- 
gen) combined  with  the  oxybase,  forming  what  was  called 
a  hydrosulphuret.    It  was  also  supposed  that  a  sulphide  of 
an  alkalifiable  metal,  by  solution  in  water,  would  be  con- 
verted into  an  oxybase  by  the  oxygen  of  the  water;  while 


LITHIUM.  289 

the  hydrogen,  with  a  double  proportion  of  sulphur,  form- 
ing hisulphuretted  hydrogen,  would  combine  with  the  oxy- 
base. 

1557.  Through  the  sagacity  and  industry  of  Berzelius, 
much  knowledge  has  of  late  years  been  acquired  respect- 
ing the  combinations  of  sulphur  with  the  alkaline  metals. 
He  mentions  seven  compounds,  in  which,  supposing  the 
quantity  of  the  potassium  in  each  to  be  the  same,  the  quan- 
tities of  the  sulphur  are  severally  1,  2,  3,  3£,  4,  4^,  5. 

1558.  To  remember  the  details  respecting  the  prepara- 
tion and  characteristics  of  these  sulphides,  would  be  too 
great  a  burthen  for  the  memory  of  those  who  are  not  so 
situated  as  to  take  a  particular  interest  in  them. 

1559.  Sulphides  of  the  metals  of  the  earths  and  alkalies, 
on  being  moistened  with  water,  evolve  sulphydric  acid,  and 
produce  this  result  still  more  actively  on  being  subjected 
to  chlorohydric  acid. 

1560.  The  selenides  of  the  metals  of  the  earths  and 
alkalies  may,  in  most  cases,  be  produced  by  heating  the 
metal  with  selenium.     The  selenides  of  these  metals  bear 
a  great  resemblance  to  the  sulphides,  and  when  heated  are 
reduced  to  the  metallic  state,  producing  the  smell  of  horse- 
radish. 

1561.  The  tellurides  are  but  little  known,  and,  except 
so  far  as  they  act  as  telluracids  or  telluribases,  so  as  to 
give  pretensions  to  tellurium  to  be  placed  among  the  basa- 
cigen  elements,  they  are  uninteresting. 

Experimental  Illustrations. 

1562.  Sulphides  in  solution  exhibited.     Earths  precipi- 
tated by  acids. 

OF  METALS  PROPER. 

1563.  The  metals  included  under  this  head,  are  gold, 
platinum,  silver,  mercury,  copper,  lead,  tin,  bismuth,  iron,  zinc, 
arsenic,    antimony,  palladium,  rhodium,    iridium,    osmium, 
nickel,  cadmium,  chromium,  cobalt,  columbium,  manganese, 
molybdenum,  titanium,  tungsten,  uranium,  cerium,  and  va- 
nadium. 

37 


290  INORGANIC  CHEMISTRY. 

SECTION  I. 

OF  GOLD. 

1564.  Gold  is  usually  found  in  nature  nearly  pure.     It  is  not  liable,  like 
other  metals,  to  be  disguised  by  a  union  with  oxygen  or  sulphur.     The 
precipitate  obtained  from  a  solution  of  gold  coin  in  aqua  regia,  by  the  green 
sulphate  of  iron,  is  pure'  gold.     This  metal  is  also  purified  by  exposure  to 
heat  and  air,  or  by  nitric  acid,  by  which  means  baser  metals  are  oxidized; 
as  in  the  processes  of  cupellation  and  parting. 

1565.  From  the  sands,  or  ores,  in  which  they  exist  naturally,  minute 
portions  of  gold  are  collected  by  trituration  with  mercury,  with  which  they 
amalgamate.     The  mercury  is  distilled  from  the  amalgam  thus  obtained, 
by  means  of  an  iron  alembic. 

1566.  Properties. — The  specific  gravity  of  gold  is  19.3,  and  its  equiva- 
lent 200.    Its  colour  and  lustre  are  too  well  known  to  need  description.    It  is 
the  most  malleable  and  ductile  metal,  and  suffers  the  least  by  exposure  to  air 
and  moisture.     Gold  leaf,  which  is  about  1000  times  thinner  than  printing 
paper,  retains  its  lustre  in  the  air.     Gold  leaf  transmits  a  greenish  light, 
but  it  is  questionable  whether  it  be  truly  translucent.     Placed  on  glass,  and 
viewed  by  transmitted  light,  it  appears  like  a  retina.     It  is  erroneously 
spoken  of  as  a  continuous  superfices. 

1567.  Gold  fuses  at  a  low  white-heat,  but  requires  the  temperature  pro- 
duced by  the  compound  blowpipe,  by  galvanism,  or  by  the  explosive  power 
of  electricity,  to  volatilize  or  oxidize  it.     Its  not  being  liable  to  tarnish  by 
exposure,  is  due  to  the  weakness  of  its  affinity  for  oxygen  or  sulphur. 

1568.  When   a  solution   of  chloride  of  gold  is   mixed  with  sulphuric 
ether,  the  ether  takes  the  metal  from  the  chlorine,  retaining  it  in  solution. 
If  iron  or  steel  be  moistened  with  this  ethereal  liquid,  it  is  productive  of  a 
slight  gilding. 

1569.  Phosphorus,  carbon,  and  the  baser  metals,  also  hydrogen  gas  and 
its  compounds,  by  a  superior  affinity  for  oxygen  or  chlorine,  precipitate 
gold  from  the  solution  of  its  chloride  in  the  metallic  form. 

1570.  The  abstraction  of  oxygen  precipitates  gold,  by  liberating  the 
hydrogen  of  water.      The  hydrogen  thus  liberated,  takes  chlorine  from 
gold,  forming  of  course  chlorohydric  acid,  which  has  no  affinity  for  this 
metal,  unless  in  the  state  of  chloride.    As  oxygen  is  necessary  to  the  base  of 
an  oxysalt,  so  chlorine  is  indispensable  to  the  constitution  of  a  chlorosalt. 

1571.  The  union  of  gold  with  mercury,  was  adduced  as  an  exemplifica- 
tion of  simple  chemical  combination.  (515.)     The  compound  thus  formed, 
when  the  ingredients  are  in  due  proportion,  is  of  great  use  as  the  mean  of 
that  kind  of  gilding  which  is  the  most  firm  and  durable.     The  affinity 
between  the  mercury  and  copper,  renders  it  easy  to  coat  with  the  amalgam 
the  surface  of  any  mass  formed  of  this  metal.     Subsequently,  the  mercury 
may  be  driven  off  by  heat,  leaving  a  pellicle  of  gold  upon  the  cupreous  sur- 
face, which  only  requires  burnishing,  in  order  to  display  the  colour  and 
brilliancy  of  gold. 

1572.  With  arsenic,  gold  combines  energetically,  absorbing  this  metal 
in  the  form  of  vapour,  at  a  red-heat,  without  changing  colour.     Gold  loses 
its  malleability  by  acquiring  yjo"th  of  its  weight  of  arsenic.     Probably  gold 
may  be  united  with  all  the  metals.     Phosphorus  forms  with  it  a  brittle 
compound. 


GOLD.  291 

1573.  The  affinity  between  chlorine  and  gold  is  pre-eminently  energetic. 
A  combination  ensues,  whether  the  metal  be  heated  in  the  gas,  or  presented 
to  it  in  aqueous  solution,  or  in  aqua  rrgia,  which  is  essentially  a  solution  of 
chlorine  in  water.     Aqua  rogia  is  produced  by  the  mixture  of  chlorohydric 
with  nitric  acid.     It  ought  not,  however,  to  be  considered  as  a  combination 
of  them.    As  soon  as  the  mixture  is  effected,  a  decomposition  of  both  of  the 
acids  commences. 

1574.  One  atom  of  nitric  acid,  by  yielding  three  out  of  its  five  atoms  of 
oxygen,  (957,)  can  take  all  the  hydrogen  from  three  atoms  of  chlorine.  (874.) 
Of  course,  three  atoms  of  chlorine  and  one  of  nitric  oxide  are  emancipated. 
If  the  acids  employed  be  concentrated,  both  the  nitric  oxide  and  the  chlo- 
rine are  evolved ;  but  if  there  be  a  sufficiency  of  water,  the  chlorine  remains 
in  union  with  it,  forming  a  more  concentrated  aqueous  solution  of  chlorine 
than  can  otherwise  be  made.     Excepting  that  it  contains  chlorine  in  a 
higher  degree  of  concentration,  which  of  course  enables  it  to  act  with  more 
energy,  aqua  regia  does  not  differ,  in  its  solvent  powers,  from  a  solution  of 
chlorine  in  water.     It  cannot  properly  be  considered  as  a  distinct  acid; 
since  it  only  acts  by  imparting  chlorine,  being  incapable,  as  an  aggregate, 
of  entering  into  combination. 

1575.  The  name  of  aqua  regia,  or  royal  water,  was  given  to  this  solvent, 
on  account  of  its  property  of  dissolving  gold,  the  alleged  king  of  metals. 
Since  the  promulgation  of  the  French  nomenclature,  it  has  been  called 
nitro-muriatic  acid;  but  as  this  conveys  a  false  idea  of  its  nature,  I  would 
call  it  by  its  old  name,  aqua  regia,  or,  if  a  new  name  be  necessary,  I 
would  suggest  that  of  nitrohydrous  chlorine.     Latterly  Gay-Lussac  has 
alleged  that  iodic  acid  is  a  solvent  of  gold ;  and  by  Mitscherlich,  the  same 
power  is  ascribed  to  selenic  acid.    When  boiled  with  three  parts  of  sulphur, 
and  one  of  potash,  one  part  of  gold  is  dissolved  as  an  ingredient  in  a  solu- 
ble sulphosalt.  (1541.) 

Of  the  Compounds  of  Gold  icith  Oxygen. 

157G.  By  subjecting  a  protochloride  of  gold  to  a  solution  of  caustic  potash,  oxide 
of  potassium,  the  chlorine  and  oxygen  exchange  places;  so  that  a  protoxide  of  gold, 
and  chloride  of  potassium  result.  The  trioxide  of  gold  is  obtained  by  digesting  an 
aqueous  solution  of  the  bichloride  with  magnesia  in  slight  excess.  This  oxide,  which 
is  capable  of  acting  both  as  an  oxacid  and  as  an  oxybase,  in  this  instance  acting  in 
the  former  capacity,  combines  with  the  magnesia,  and  constitutes  an  aurate,  of  which 
the  greater  part  precipitates,  while  the  remainder  continues  in  solution.  The  preci- 
pitate should  be  washed  with  water  until  it  ceases  to  acquire  a  yellow  colour  by  the 
addition  of  chlorohydric  acid.  It  should  then  be  digested  with  nitric  acid,  which 
combines  with  the  magnesia,  and  thus  isolates  the  trioxide.  If  the  nitric  acid  em- 
ployed, be  concentrated,  we  obtain  the  trioxide  in  an  anhydrous  state,  and  of  a  brown 
colour;  but  if  dilute,  as  a  yellowish-red  hydrate. 

1577.  The  protoxide  consists  of  one  atom  of  gold  and  one  of  oxygen,  the  trioxide, 
of  one  of  gold  and  three  of  oxygen.     Hence,  agreeably  to  the  example  of  Thenard, 
I  designate  it  as  a  frzoxide.  (756.)     Acting  as  a  base,  this  oxide  combines  with  nitric 
or  sulphuric  acid.     It  is  precipitated  from  these  combinations  by  water,  which  acts, 
probably,  in  this  case,  as  an  oxybase  of  hydrogen.  (826.) 

1578.  As  an  oxacid,  trioxide  of  gold  unites  with  all  the  alkalies  and  alkaline  earths. 
The  aurate  of  ammonia,  a  compound  which  explodes  by  percussion,  has  long  been 
known  under  the  name  of  fulminating  gold.     Berzelius  alleges  that  there  are  two 
kinds;  one,  containing  an  excess  of  ammonia,  detonates  more  powerfully  ;  the  other, 
formed  with  a  lesser  quantity  of  the  alkali,  contains  chloride  of  gold,  by  which  its 
power  is  enfeebled. 

1579.  A  precipitate,  of  a  beautiful  purple  colour,  may  be  obtained  either  by  mixing 
diluted  solutions  of  the  chlorides  of  tin  and  gold ;  or  by  immersing  an  ingot  of  tin, 
or  tin  foil,  in  a  solution  of  chloride  of  gold,  containing  some  free  chlorohydric  acid. 
To  this  precipitate  the  name  of  purple  powder  of  Cassius  has  been  given.     I  infer 
from  the  account  of  this  compound,  given  by  Berzelius,  that  it  consists  of  gold,  tin, 


292  INORGANIC  CHEMISTRY. 

hydrogen,  and  oxygen.     Respecting  the  mode  of  combination  there  is  some  ob- 
scurity. 

1580.  In  consequence  of  this  property  of  producing  the  purple  of  Cassius,  tin, 
whether  in  the  metallic  state  or  that  of  dissolved  protochloride,  is  the  best  test  for 
gold. 

1581.  Berzelius  does  not  consider  the  purple  powder  into  which  gold  is  reduced 
by  successive  electric  discharges,  as  any  thing  more  than  metallic  gold  in  a  state  of 
minute  division. 

Of  the  Compounds  of  Gold  with  the  Halogen  Bodies. 

1582.  The  protochloride  of  gold  is  obtained  by  exposing  the  trichloride  to  a  gentle 
heat,  which  drives  off  two  atoms  of  chlorine,  leaving  the  gold  in  combination  with 
the  remainder.     If  the  heat  be  carried  too  far,  it  is  apt  to  decompose  the  protochlo- 
ride into  metallic  gold  and  chlorine.     On  this  account  it  is  better  to  stop  the  opera- 
tion before  the  trichloride  is  entirely  decomposed,  and  to  wash  the  resulting  mass 
with  water,  which  removes  the  trichloride,  and  leaves  the  protochloride,  which  is 
insoluble  in  that  fluid  when  cold.     A  solution  of  the  trichloride  of  gold  is  obtained 
when  gold  is  dissolved  in  aqua  regia,  any  excess  of  chlorohydric  acid  is  expelled 
by  heat.     It  is  of  a  pale  yellow  colour,  and  has  an  astringent  and  disagreeable  taste. 
This  chloride  combines  as  an  acid  with  the  chlorides  of  the  alkaline  metals,  forming 
chloroaurates.     Hence  I  consider  this  as  entitled  to  the  appellation  of  chloroauric 
acid.     The  trichloride  of  gold,  as  its  name  implies,  is  composed  of  one  atom  of  gold, 
and  three  atoms  of  chlorine. 

1583.  Bromine  forms  with  gold  a  tribromide,  which  corresponds  in  composition 
and  chemical  properties  with  the  trichloride  of  the  same  metal.     The  iodide  of  gold 
agrees,  in  composition  and  chemical  relations,  with  the  protochloride  of  gold.     The 
cyanide  of  gold  appears  to  act  as  an  acid. 

Of  the  Compounds  of  Gold  with  Sulphur. 

1584.  Gold  forms  with  sulphur  a  protosulphide  and  a  trisulphide.     The  protosul- 
phide  is  formed  by  passing  a  current  of  sulphydric  acid  gas  through  a  boiling  solution 
of  the  trichloride.     It  is  of  a  deep  brown  colour,  and  is  decomposed  by  heat  into 
metallic  gold  and  sulphur.  The  trisulphide  may  be  precipitated  by  passing  a  current 
of  sulphydric  acid  into  a  dilute  solution  of  the  trichloride,  or  by  adding  an  acid  to  a 
solution  of  the  sulphurate  of  potassium.     The  trisulphide  is  of  a  deep  yellow  colour, 
and  is  decomposed  by  heat.     With  sulphobases  it  acts  as  an  acid,  but  with  the  more 
powerful  sulphacids  as  a  base. 

Experimental  Illustrations. 

1585.  Some  gold  leaf  is  placed  in  two  glass  vessels. 
Nitric  acid  being  poured  into  one,  and  chlorohydric  acid 
into  the  other,  the  gold  is  not  acted  upon;  but  when  the 
contents  of  the  two  vessels  are  united,  the  gold  disap- 
pears. 

1586.  Gold,  dissolved  by  aqua  regia,  and  precipitated 
by  sulphate  of  iron,  or  by  chloride  of  tin.     A  cylinder  of 
phosphorus,  immersed  in  a  solution  of  the  metal,  acquires 
the  appearance  of  a  cylinder  of  gold.     Separation  of  gold 
from  its  solution  by  ether.     Effects  of  the  ethereal  solu- 
tion exhibited.     Action  of  mercury  on  gold  leaf. 


PLATINUM.  293 

SECTION  II. 

OF   PLATINUM. 

1587.  This  metal  is  found  in  South  America,  and  in  Russia,  in  an  im- 
pure granular  form,  known  as  the  native  grains  of  platinum.     In  addition 
to  this  metal,  the  native  grains  contain  several  other  metallic  substances  in 
a  state  of  combination  or  mixture.    The  aggregate  thus  described  is,  for  the 
most  part,  soluble  in  aqua  regia;  the  habitudes  of  platinum,  in  this  respect, 
as  well  as  in  others,  being  more  analogous  to  those  of  gold  than  any  other 
body  in  nature.    On  adding  to  a  solution  of  the  native  grains  of  platinum,  in 
aqua  regia,  a  solution  of  sal-ammoniac,  an  orange-yellow  precipitates,  but 
little  soluble  in  water,  is  obtained.     This  being  carefully  washed  and  desic- 
cated, and  finally  exposed  to  a  red-heat,  in  a  platina,  porcelain,  or  black 
lead  crucible,  the  metal  is  isolated  in  a  mass  so  porous,  as  to  have  received 
the  name  of  platina  sponge,  from  its  resemblance  in  structure  to  the  well 
known  substance  to  which  this  name  belongs.     By  extreme  mechanical 
pressure  the  platina  sponge  is  so  far  consolidated  that  by  intense  heat  and 
hammering  it  is  welded  into  a  perfectly  tenacious  mass,  having,  in  a  high 
degree,  all  the  attributes  of  a  noble  metal.  (1404.) 

1588.  I  have  lately  been  enabled,  by  an  improvement  in  my  hydro-oxy- 
gen blowpipe,  to  fuse  twenty-five  ounces  of  platinum  into  a  malleable  mass. 
The  metal  thus  obtained,  is  less  liable  to  flaws  than  that  produced  by  the 
welding  process  above  described.     My  process  is  especially  important  as 
enabling  us  to  unite  old  platina  ware,  or  clippings,  into  malleable  masses  of 
convenient  dimensions,  without  re-solution  in  aqua  regia.    The  necessity  of 
taking  this  last  mentioned  course,  reduce^  platina  in  that  state,  to  a  value 
not  more  than  £  higher  than  that  of  the  native  grains.  (394.) 

1589.  According  to   Berzelius,   platinum,  as  obtained   by  the   process 
above-mentioned,  is  alloyed  with  iridium,  and  inferior  to  the  pure  metal  in 
colour,  brilliancy,  ductility,  and  malleability ;  while  at  the  same  time  it  is 
stronger  and  more  suitable  for  the  purposes  for  which  it  is  usually  em- 
ployed.    It  may  be   obtained   pure,    by  precipitating   chloroplatinic  acid 
from  its  aqueous  solution  by  chloride  of  potassium,  igniting  the  precipitate, 
redissolving  it,  and  precipitating  again  by  sal-ammoniac;  and  lastly,  by  re- 
ducing the  precipitate  by  ignition  to  the  spongy  form,  from  which  by  pres- 
sure and  the  welding  process,  it  may  be  made  coherent  and  malleable,  as 
in  the  abovementioned  process  for  obtaining  the  metal. 

1590.  Properties. — The  colour  of  this  metal,  as  ordinarily  obtained,  is 
intermediate  between  that  of  silver  and  steel;  but  when  pure,  as  above 
stated,  it  resembles  silver  both  in  colour  and  softness,  more  than  when 
alloyed  with  iridium.     Its  specific  gravity  is  21.53.     A  cubic  inch  of  it 
weighs  more  than  three-fourths  of  a  pound.  It  is  nearly  twice  as  heavy  as  lead, 
being  the  heaviest  body  known.     It  is  less  ductile  and  malleable  than  gold, 
but  harder  and  more  tenacious;  though,  in  these  respects,  inferior  to  iron, 
Like  iron,  it  is  susceptible  of  being  hammered  and  welded  at  a  white-heat. 
It  can  neither  be  oxidized  nor  melted  by  the  highest  temperatures  of  the  air- 
furnace,  or  forge.     It  was  first  fused  in  a  focus  of  the  solar  rays,  afterwards 
by  means  of  a  stream  of  oxygen  gas  on  ignited  charcoal,  but  much  more 
easily  by  the  compound  blowpipe,  under  which  it  was  first  oxidized  and  dis- 
sipated by  heat.     It  fuses  and  burns  «\-isi]\  in  the  Voltaic  circuit,  and  is 


294  INORGANIC  CHEMISTRY. 

dispersed  and  oxidized  by  mechanical  electricity.     It  is  one  of  the  worst 
conductors  of  heat  among  metals. 

1591.  In  its  habitudes  with  oxygen,  chlorine,  and  the  acids,  it  is  analo- 
gous to  gold,  being,  like  that  metal,  detected  by  protochloride  of  tin,  which 
produces  with  it  a  claret  colour.     It  unites  so  energetically  with  tin  at  a 
red-heat,  as  to  occasion  the  phenomena  of  combustion.  (348.)     When  in  a 
divided  state,  as  obtained  by  igniting  the  chloroplatinate  of  ammonium,  it 
amalgamates  with  mercury  by  trituration. 

1592.  Platinum  combines  with  boron,  silicon,  and  phosphorus.     On  ac- 
count of  its  infusibility  at  the  highest  temperatures  produced  by  the  air-fur- 
nace, or  forge,  and  its  insusceptibility  of  being  corroded  by  the  acids  usually 
employed  in  chemical  processes,  it  is  much  used  by  chemists  for  crucibles, 
evaporating  vessels,  and  spoons;  also  in  experiments  in  which  Voltaic  series 
are  resorted  to  as  a  means  of  decomposition.     I  employ  it  in  my  galvano- 
ignition  apparatus.  (335.)     At  high  temperatures,  it  is  acted  upon  by  the 
alkaline  hydrates,  and  by  almost  all  metals,  especially  tin  and  lead.     I  had 
a  platinum  crucible  perforated,  by  fusing  in  it  some  flint  glass,  which  con- 
sists mainly  of  lead,  silicic  acid,  and  potash. 

1593.  The  equivalent  of  platinum  is  99. 

Of  the  Compounds  of  Platinum  with  Oxygen. 

1594.  Platinum  forms  a  protoxide,  consisting  of  one  atom  of  metal  and  one  atom 
of  oxygen,  which  may  be  obtained  from  the  chloride,  by  the  addition  of  potash.     It 
forms  also  a  bioxide,  containing  two  atoms  of  oxygen  to  one  of  metal,  as  the  name 
implies.     The  protoxide  acts  as  an  oxybase  only ;  the  bioxide,  both  as  an  oxybase 
and  oxacid.     In  the  last  mentioned  capacity  it  enters  into  combination  with  ammo- 
nia, in  the  compound  called  fulminating  platinum,  and  which  we  may  with  propriety 
call  platinate  of  ammonia,  or  ammonium.     Dr.  Thomson  alleges  the  existence  of 
some  other  oxides  of  platinum. 

Of  the  Compounds  of  Platinum  with  the  Halogen  Class, 

1595.  Of  Chloroplatinic  Acid. — The  platinum,  in  the  solution  of  aqua 
regia  above  described,  being  in  the  state  of  a  bichloride  and  acting  as  an  acid 
agreeably  to  my  fundamental  definition,  (631,)  is  capable  of  combining 
with  other  chlorides  acting  as  chlorobases.     With  either  the  chloride  of 
potassium,  or  the  chloride  of  ammonium,  (sal  ammoniac,  1109,)  it  forms 
compounds  which  are  but  very  sparingly  soluble  in  water.      Hence  the 
precipitate  resulting  from  the  addition  of  the  last  mentioned  chlorobase,  and 
the  employment  of  the  chloride  (or  chlorobase)  of  potassium,  in  the  process 
recommended  by  Berzelius.  (1589.)      But  since  the  bichloride  of  platinum 
acts  as  an  acid,  it  is  proper  to  designate  it  as  a  chloroplatinic  acid.     In  this 
I  am  supported  by  the  authority  of  Dr.  Thomson.     It  follows  that  the  pre- 
cipitates obtained  as  above  described,  are  severally  chloroplatinates  of  am- 
monium, and  potassium. 

1596.  The  superior  solubility  of  the  chloroplatinate  of  sodium,  enables 
us  to  distinguish  solutions  in  which  this  metal  exists  as  the  radical,  from 
those  in  which  potassium  performs  the  same  part;  as  with  the  latter  only 
is  orange-coloured  precipitate  obtained,  on  adding  chloroplatinic  acid. 

1597.  Of  Chloroplatinous  Acid. — This  name  is  given  to  the  protochlo- 
ride of  platinum,  as  it  is,  according  to  Berzelius,  capable  of  combining  with 
the  same  chlorobases  as  chloroplatinic  acid.     Chloroplatinous  acid  is  ob- 
tained by  exposing  the  bichloride  (chloroplatinic  acid)  to  heat.    It  is  alleged 
to  have  a  grayish  colour,  and  to  be  insoluble  in  water.     Its  compounds 
with  chlorobases  must  consistent^  be  called  chloroplatinites. 


PLATINUM.  295 

Experimental  Illustrations. 

1598.  Platinum  exhibited  in  the  state  of  native  grains, 
and  in  the  malleable  state.  Precipitated  from  its  solution 
by  chloride  of  ammonium,  and  chloride  of  tin.  A  precipi- 
tate produced  in  salts  of  potash  by  chloride  of  platinum, 
distinguishes  them  from  salts  of  soda.  Combustion  of  pla- 
tinum with  tinfoil. 

Of  the  Nomenclature  of  Compounds  formed  with  Halogen  Bodies,  called 
Double  Salts  by  Berzelius. 

1599.  In  order  to  present  an  intelligible  view  of  the  discordant  names  of 
the  salts  above  described,  I  will  here  subjoin  a  table  of  the  names  of  some 
compounds  formed  with  chlorine  by  platina,  of  which  mention  has  been 
made.  (1596.) 

Table  of  the  various  Names  given  to  the  Double  Chlorides,  such  as  those 
described  in  the  case  of  Platina. 

Names  according  to  the  old  Theory  of  the  Muriates. 

Potash,  } 

Soda,  Muriate  of  <J  Platinum. 

Ammoniacal,  or  Ammonia,  S 


5  Platii 


Names  according  to  Brande. 

t  Potassium. 
Platino  bichloride  of  -  <  Sodium. 

(  Ammonium. 
Berzelian  Names. 

t  Ammonique. 
Chlorure  platinico,  <  Sodique. 

f  Ammonique. 

Names  according  to  Thomson  adopted  by  me,  before  I  was  aware  of  their 
adoption  by  this  distinguished  Author. 

C  Potassium. 
Chloroplatinate  of  <  Sodium. 

(  Ammonium. 

The  Compounds  formed  with  the  Protochloride, 
are  by  Berzelius  designated  as  follows  : 

i  Potassique. 
Chlorure  platinoso,  -  -  <  Sodique. 

(  Ammonique. 

and  are  in  this  Compendium  designated  by  me, — 

C  Potassium. 
Chloroplatinite  of  <  Sodium. 

f  Ammonium. 


296  INORGANIC  CHEMISTRY. 

1600.  In  order  to  have  the  nomenclature  of  the  analogous  compounds, 
in  which  other  chlorobases  or  chloracids  are  introduced,  it  is  only  requisite 
to  change  the  corresponding  epithet  m  the  formula. 

1601.  By  changing  the  syllables  indicating  the  halogen  ingredient,  the 
nomenclatures  of  any  of  the  double  salts  formed  by  any  of  the  halogen 
bodies,  may  be  seen,  agreeably  to  the  language  of  Brande,  of  Berzelius,  or  of 
Thomson  and  myself. 

Of  Bromides,  Iodides,  and  Cyanides. 

1602.  Bromine  forms  with  platinum  a  compound  analogous  in  composition  to  the 
bichloride  of  that  metal,  and  which,  from  its  chemical  properties,  is  entitled  to  the 
appellation  of  bromoplatinic  acid. 

1603.  Iodine  and  fluorine  both  form  compounds  with  platinum.     The  fluoride  of 
platinum  acts  as  an  acid ;  the  properties  of  the  iodide  in  this  respect  are  unknown. 

1604.  Cyanogen  forms  two  compounds  with  platinum.     The  percyanide  combines 
with  cyanobases  as  an  acid,  and  of  course  may  be  designated  as  cyanoplatinicacid. 

Of  the  Compounds  of  Platinum  icith  Sulphur. 

1605.  Platinum  combines  with  sulphur  in  two  proportions.     Both  sulphides  com- 
bine as  sulphobases  with  sulphacids,  but  the  persulphide  unites  as  a  sulphacid  with 
sulphobases  of  the  alkalifiable  metals. 

Of  the  Power  of  Platinum,  and  other  Metals  in  a  divided  or  spongy  form,  to  induce 

Chemical  Reaction. 

1606.  In  the  spongy  form  in  which  platinum  remains  after  the  chlorine  and  am- 
monia of  the  chloroplatinate  are  expelled,  it  has  the  wonderful  power  of  causing  the 
inflammation  of  a  mixture  of  hydrogen  and  oxygen  gas.     I  have  ascertained  that 
this  power  is  acquired  by  asbestos,  porcelain  earth,  and  charcoal,  merely  by  soaking 
them  in  a  solution  of  platinum,  in  aqua  regia,  and  subsequent  desiccation  and  ignition. 
Thenard  states,  that  platinum  filings,  platinum  leaf,  or  an  association  of  fine  plati- 
num wires,  exercise,  in  a  greater  or  less  degree,  the  same  power  as  platinum  sponge. 

1607.  The  pulverulent  mass,  obtained  by  precipitating  platinum  by  zinc,  becomes 
incandescent  in  the  vapour  of  alcohol.     As  the  best  means  of  obtaining  platinum  in 
that  state  of  minute  division  in  which  it  is  most  efficacious  in  producing  this  result, 
Liebig  recommends  that  the  chloride  should  be  dissolved  in  a  lixivium  of  caustic 
potash  with  heat;  and  that  while  the  resulting  liquid  is  still  hot,  alcohol  should  be 
added  in  small  quantities,  stirring  the  mixture  until  an  effervescence  arises  from  the 
extrication  of  carbonic  acid.     This,  however,  becomes  so  active  as  to  render  a  very 
capacious  vessel  necessary  for  the  process.   The  platinum  precipitates  in  the  form  of 
a  black  powder,  which  is  to  be  separated  from  the  liquid,  and  washed  successively 
with  alcohol,  with  a  solution  of  potash,  with  chlorohydric  acid,  and  four  or  five  times 
with  water.     When  dried,  the  powder  resembles  lampblack,  and  soils  the  fingers. 
Nevertheless,  it  consists  only  of  platinum  in  a  state  of  minute  division,  since  it  may 
be  heated  to  a  cherry-red  in  the  air  or  in  oxygen,  without  losing  weight  or  undergo- 
ing any  change  in  its  properties.     These  are,  however,  destroyed  by  incandescence, 
which  restores  its  metallic  appearance.     Under  the  burnisher,  it  becomes  slightly  of 
a  metallic  gray.     In  aqua  regia,  it  dissolves  without  leaving  any  residue. 

1608.  Its  properties  are  as  follows :  like  charcoal,  it  condenses  the  gases  in  its  pores, 
with  a  development  of  heat;  and  if,  after  being  deprived  of  air  and  moisture  by  ex- 
posure to  a  vacuum  over  sulphuric  acid,  the  atmosphere  be  rapidly  admitted,  it  be- 
comes red-hot.     It  causes  the  combustion  of  hydrogen  or  alcoholic  vapour,  when  in 
contact  with  them  with  access  of  air,  and  becomes  incandescent  on  falling  on  a  sur- 
face wet  with  alcohol.     If  moistened  with  alcohol,  it  converts  it,  at  the  expense  of 
the  oxygen  of  the  air,  into  acetic  acid  and  acetic  ether.     Platinum,  however  pre- 
pared, gradually  loses  the  property  of  causing  a  union  between  oxygen  and  hydro- 
gen; but  this  property  disappears  much  more  rapidly  when  exposed  to  the  action  of 
the  air,  than  when  protected  from  its  influence.    Spongy  platinum,  moreover,  re- 
mains effective  longer  than  platinum  under  any  other  state;  unless  that  in  which  it 
is  procured  by  precipitation  by  zinc  be  an  exception.     Platinum  leaf,  which  in  the 
air  is  rendered  powerless  in  a  few  minutes,  when  in  the  form  of  a  scroll  and  in- 
cluded in  a  close  vessel,  remains  effective  for  twenty-four  hours.     The  power  of 
producing  a  union  between  hydrogen  and  oxygen,  may  be  restored  by  immersion  in 
an  acid,  or  by  incandescence. 


SILVER.  297 

1609.  Strips  of  sheet  platinum,  after  being  well  cleansed  by  exposure  as  the  elec- 
trodes of  a  Voltaic  series  ;  or  by  exposure,  with  certain  precautions  to  acids,  were 
found  by  Faraday  to  cause  the  union  of  the  elements  of  water. 

1610.  Platinum  is  not  the  only  substance  which  possesses  the  property  of  pro- 
ducing  the  combination  of  oxygen  and  hydrogen.     Gold,  precipitated  from  its  solu- 
tion by  means  of  zinc  and  subsequently  heated  to  redness,  if  assisted  by  a  tempera- 
ture of  122°,  causes  the  union  of  hydrogen  and  oxygen.     Osmium  slowly  produces 
the  same  effect,  at  a  heat  a  little  below  that  which  is  necessary  in  the  case  of  gold. 
Spongy  nickel  acts  slowly  at  the  ordinary  temperature  of  the  atmosphere.  Palladium, 
rhodium,  and  iridium  produce  the  same  effect  on  a  mixture  of  hydrogen  and  oxygen 
as  platinum,  though  with  less  intensity.    Charcoal,  porcelain,  glass,  and  rock  crystal 
produce  a  union  between  hydrogen  and  oxygen,  at  temperatures  lower  than  that  at 
which  it  would  otherwise  take  place. 

Experimental  Illustrations. 

1611.  A  mixture  of  hydrogen  and  oxygen  inflamed  by 
platinum  sponge,  or  platinated  asbestos.  Incandescence 
of  platinum  powder  produced  by  moistening  it  with  al- 
cohol. 


III. 

OF  SILVER. 

1612.  Silver  exists  in  nature  nearly  pure,  but  usually  containing  a  mi- 
nute quantity  of  gold,  copper,  arsenic,  or  iron.  It  also  exists  in  alloys, 
containing  various  equivalent  proportions  of  arsenic,  antimony,  tellurium, 
or  gold.  It  is  found,  likewise,  in  the  state  of  chloride,  iodide,  sulphide,* 
and  carbonate,  and  in  a  variety  of  galena,  the  native  sulphide  of  lead,  call- 
ed, in  consequence,  argentiferous  galena.  In  consequence  of  its  fusibility 
and  insusceptibility  of  oxidizement,  —  when  any  metallic  alloy,  containing 
it,  is  exposed  to  intense  ignition  with  access  of  air,  the  silver  is  separated 
from  any  metal  which,  when  thus  exposed,  is  liable  to  be  converted  into  an 
oxide.  In  the  small  way,  this  object  is  effected  upon  the  cupel,  in  the  ope- 
ration called  cupellation.  A  cupel  is  a  small  flat  cylinder,  made  of  bone 
earth  obtained  by  calcination,  in  the  upper  surface  of  which  there  is  a  he- 
mispherical cavity.  In  this  cavity  any  gold  or  silver  to  be  refined  is  placed 
with  a  portion  of  lead.  The  cupel  is  then  placed  in  a  small  earthenware 
oven,  called  a  muffle,  and  exposed  to  a  heat  sufficient  to  render  and  keep 
the  metals  fluid.  Under  these  circumstances,  the  lead  is  oxidized  and  vitri- 
fied, and  promotes  a  similar  change  in  any  other  metals  present,  which  are 
susceptible  of  oxidizement  under  the  circumstances  in  question.  The  vitre- 
ous matter,  thus  produced,  is  absorbed  by  the  bone  earth.  After  the  process 
has  endured  sufficiently,  only  the  gold  and  silver,  or  other  noble  metals, 
should  any  be  present,  can  remain  upon  the  cupel.  This  stage  of  the  pro- 
cess is  indicated  by  the  metallic  surface  being  no  longer  obscured  by  any 
film  of  oxidized  matter.  As  in  the  cases  in  which  this  process  is  employed, 
no  other  noble  metals  are  liable  to  be  present  besides  gold  and  silver,  I  shall 
treat  of  it  only  in  reference  to  them. 

*  The  student  is  requested  to  recollect  that  sulphide  and  sulphuret  are  synony- 
mous. (686). 
38 


298  INORGANIC  CHEMISTRY. 

1613.  From  the  alloy  purified  upon  the  cupel,  the  silver  maybe  removed 
by  nitric  acid,  when  the  gold  does  not  exceed  a  fourth  of  the  whole.     In 
order,  therefore,  to  enable  the  nitric  acid  to  dissolve  the  silver,  the  mass  is 
fused  with  the  addition  of  as  much  of  this  metal,  as  will  establish  the  re- 
quisite ratio  between  it  and  the  gold.     This  is  called  quartation.     The 
process  of  separating  the  metals  afterwards  by  nitric  acid,  is  called  parting. 

1614.  If  the  alloy  be  subjected  to  aqua  regia,  the  gold  only  will  be  taken 
up,    The  silver  will  precipitate  as  a  chloride,  and  the  parting  will  be  effected 
the  easier,  in  proportion  as  the  quantity  present  of  the  last  mentioned  metal 
is  less. 

1615.  Silver,  contained  in  argentiferous  copper,  is  extracted  by  means 
of  lead,  in  the  process  called  liquation.     The  alloy  is  fused  with  two  and  a 
half  parts  of  the  metal  last  mentioned,  and  cast  into  thick  round  cakes. 
These  are  subsequently  exposed  in  a  reverberating  furnace,  to  a  heat  suffi- 
cient to  melt  the  silver  and  lead,  leaving  the  copper,  which  has  scarcely 
any  affinity  for  lead.     The  silver  is  afterwards  separated  from  the  lead  by 
cupellation. 

1616.  Pure  silver  may  be  obtained  from  silver  coin  by  various  means. 
The  white  crystals  spontaneously  afforded  by  a  solution  of  the  coin  in  nitric 
acid,  cautiously  drained,  and  washed  with  a  portion  of  water  barely  suffi- 
cient to  remove  every  vestige  of  green,  yield  a  solution  of  pure  silver.    The 
residual  liquid  may  be  decomposed  by  copper,  and  the  precipitate  redis- 
solved,  and  crystallized  by  evaporation;  and  thus  a  fresh  crop  of  white 
crystals  may  be  procured.     The  whiteness  of  the  crystals  may  be  deemed 
the  criterion  of  their  purity.    Silver  precipitated  by  mercury,  as  in  the  case 
of  the  arbor  Dianas,  only  requires  ignition  to  render  it  pure. 

1617.  Properties. — Excepting  steel,  silver  is  susceptible  of  the  highest 
degree  of  metallic  brilliancy;  and  next  to  gold,  it  is  the  most  malleable  and 
ductile  metal.     In  metallic  whiteness,  it  is  pre-eminently  beautiful,  and  in 
tenacity  inferior  only  to  iron,  copper,  and  platinum.     Its  specific  gravity  is 
10.5,  and  equivalent  108.     It  is  the  best  conductor  of  caloric,  fuses  at  a 
low  white  heat,  is  as  difficult  to  oxidize  in  the  fire  as  gold,  but  is  more  liable 
to  tarnish  when  exposed  to  the  atmosphere,  from  its  susceptibility  to  the 
action  of  sulphur  and  chlorine.     Hence  it  is  blackened  by  eggs  and  by  salt 
water. 

1618.  By  the  compound  blowpipe,  electricity,  or  galvanism,  silver  is 
fused,  oxidized  and  dissipated. 

1619.  Exposed  to  nitric  acid,  it  is  oxidized  by  one  portion,  and  dissolved 
by  the  other.    In  fact  this  acid  is  its  proper  solvent.    The  resulting  nitrate, 
when  fused  and  cast  into  sticks,  forms  the  lunar  caustic  of  the  shops.     It 
consists  of  one  atom  of  acid  54,  and  one  of  oxide  116,  =  170. 

1620.  Sulphuric  acid,  when  cold,  has  no  reaction  with  silver.     At  a 
boiling  heat,  the  metal  is  oxidized  at  the  expense  of  one  portion  of  the  acid; 
and  the  oxide,  thus  formed,  is  dissolved  by  another  portion,  as  in  the  case 
of  nitric  acid. 

1621.  Silver  combines  with  phosphorus,  and  in  minute  proportion  with 
carbon  and  silicon. 

Of  the  Compounds  of  Silver  with  Oxygen. 

1622.  Silver  forms  two  oxides.     The  protoxide  is  obtained  by  decomposing  the 
nitrate  by  potash  or  soda.     It  is  of  a  deep  olive  colour,  slightly  soluble  in  water, 
and,  according  to  Thenard,  sufficiently  alkaline  to  render  syrup  of  violets  green.    It 
revives  simply  by  the  influence  of  heat,  and  of  course  is  reducible  when  heated  with 
those  radicals,  which,  under  the  same  circumstances,  combine,  per  se,  with  oxygen. 


SILVER.  299 

When  thus  reduced,  it  must  of  course  produce  the  vivid  ignition  which  is  consequent 
to  the  presence  of  pure  oxygen. 

1623.  This  oxide,  by  uniting  with  ammonia,  produces  a  fulminating  compound,  so 
dangerous  that  few  persons  have  been  willing  to  encounter  the  risk  of  making  it. 
This  should  not  be  confounded  with  the  fulminate  of  silver,  consisting  of  the  same 
metal  and  fulminic  acid.  (1312,  &c.) 

16<J4.  The  peroxide  of  silver  is  formed  around  the  wire,  proceeding  from  the  posi- 
tive pole  of  the  Voltaic  series,  when  a  weak  solution  of  nitrate  of  silver  is  placed  in 
the  circuit.  It  crystallizes  in  long  needles,  endowed  with  a  metallic  brilliancy.  It 
does  not  combine  with  acids,  but  when  presented  to  them,  by  a  partial  relinquish- 
ment  of  oxygen,  passes  to  the  state  of  protoxide.  This  oxide  does  not  act  either  as 
a  base  or  an  acid.  It  detonates  with  phosphorus,  if  struck  with  a  hammer  while  in 
contact  with  that  substance ;  and  when  subjected  to  ammonia,  disengages  nitrogen 
from  it  by  oxidizing  the  hydrogen. 

1625.  The  protoxide  of  silver  consists  of  one  atom  of  silver,  equivalent  108,  and 
one  of  oxygen,  equivalent  8  =  116. 

1626.  Some  chemists  suppose  the  existence  of  a  suboxide  of  silver. 

Of  the  Compounds  of  Silver  with  the  Halogen  Class. 

1627.  Silver  unites  with  chlorine  when  heated  in  it,  or  presented  to  it  in  solution. 
The  resulting  chloride  is  one  of  the  most  insoluble  combinations.     Hence,  silver 
is  not  soluble  in  aqua  regia,  or  any  other  liquid  containing  chlorine;  and  on  this 
account,  soluble  chlorides  yield  a  precipitate,  when  solutions  of  silver  are  added  to 
them. 

1628.  The  chloride  of  silver  is  white  and  tasteless,  and,  according  to  Thenard, 
when  exposed  to  light,  is  decomposed,  forming  a  subchloride.    It  combines  as  a  base 
with  the  electro-negative,  and  as  an  acid  with  the  electro-positive  chlorides. 

1629.  It  is  susceptible  of  fusion  without  decomposition,  forming  what  was  called 
by  the  old  chemists,  luna  cornea,  or  horn  silver. 

1630.  Chloride  of  silver  is  soluble  in  liquid  ammonia,  forming  chloroargentate  of 
ammonium.     It  may  be  decomposed  by  hydrogen,  if  brought  into  contact  with  this 
gas  in  its  nascent  state,  as  when  evolved  from  zinc  or  iron  by  a  diluted  acid.     It  is 
easily  decomposed  by  the  compound  blowpipe,  supplied  with  hydrogen  and  atmos- 
pheric air;  also  by  fusion  with  the  fixed  alkalies,  or  when  boiled  in  water  with 
shreds  of  iron.     The  formation  and  subsequent  decomposition  of  the  chloride,  is  one 
of  the  modes  of  obtaining  pure  silver. 

1631.  The  chloride  of  silver  is  composed  of  one  atom  of  silver,  and  one  atom  of 
chlorine. 

1632.  Bromine  and  iodine  form,  with  silver,  compounds  analogous  in  composition 
to  the  chloride.    The  bromide  and  iodide,  acting  as  acids,  combine  with  the  bromides 
and  iodides  of  the  alkalifiable  metals,  acting  as  bases.     A  native  iodide  of  silver  has 
been  found  in  Mexico. 

1633.  Fluorine  and  cyanogen  both  combine  with  silver;   the  fluoride  acts  as  a 
base,  the  cyanide  as  an  acid- 

Of  the  Compound  of  Silver  with  Sulphur. 

1634.  The  sulphide  of  silver  is  solid,  ductile,  easy  to  cut,  of  a  lead-gray  colour, 
with  a  metallic  brilliancy,  more  fusible  than  silver,  crystallizable  in  cubes  or  octo- 
hedra,  and  indecomposable  by  fire.     It  acts  as  a  powerful  sulphobase. 

1635.  This  sulphide  is  produced  whenever  silver  is  exposed  to  sulphur,  or  sulphy- 
dric  acid.     The  blackening  of  silver  spoons  by  eggs,  is  ascribed  to  the  existence  of 
a  minute  portion  of  sulphur  in  the  albumen.     The  impression  has  been  entertained 
that  persons,  who  use  the  water  of  the  white  sulphur  springs  freely,  find  silver  coin, 
carried  about  them,  blackened  by  the  sulphur  introduced  into  the  blood.    This,  how- 
ever, may  arise  from  their  frequenting  the  spring,  and  thus  exposing  the  silver  about 
their  persons  to  the  action  of  the  sulphydric  acid  gas  which  is  continually  evolved 
from  the  water.     I  am,  however,  far  from  deeming  the  fact  improbable.     It  would, 
a  priori,  be  no  more  surprising  that  the  animal  frame  should  be  imbued  with  sulphur 
than  with  mercury. 

Experimental  Illustrations. 

1636.  Exhibition  of  an  assay  furnace  and  muffle;  also 
of  a  cupel.     Oxidizement  and  solution  of  silver  in  nitric 


300  INORGANIC  CHEMISTRY. 

acid  exemplified;  also  its  precipitation  by  chlorides,  phos- 
phates, arsenites,  arseniates,  copper,  and  mercury.  Fused 
subnitrate  of  silver,  or  lunar  caustic,  exhibited.  (1619.) 


SECTION   IV. 

OF  MERCURY. 

1637.  This  well  known  metal  is  found  in  nature  in  the 
metallic  state,  pure,  and  in  union  with  silver;  also  in  the 
states  of  sulphide  and  of  chloride.     It  is  obtained  princi- 
pally from  the  native  sulphide,  cinnabar,  the  most  abun- 
dant and  prolific  of  its  ores,  by  distillation  with  the  hy- 
drate of  lime.     In  this  country  it  may  always  be  procured 
nearly  pure,  in   the  iron  bottles  in  which  it  is  import- 
ed.    It  is  alleged  that  mercury  may  be  purified  by  distil- 
lations from  iron  filings.     I  once  distilled  several  hundred 
pounds  in  this  way  for  my  mercurial  reservoir,  but  did  not 
find  it  to  be  quite  pure  afterwards.    A  better  mode  is  to  di- 
gest it  at  a  heat  below  the  boiling  point,  with  dilute  sulphu- 
ric acid  in  a  glass,  porcelain,  or  stoneware  vessel.    Under 
these  circumstances,  any  metal  having  a  greater  affinity  for 
oxygen  than  mercury,  will  be  taken  up  by  the  acid. 

1638.  If  on  being  agitated  in  a  cup  of  white  porcelain 
mercury  does  not  soil  the  surface,  it  may  be  considered  as 
pure. 

1639.  When  triturated  or  violently  shaken  with  other 
matter,  so  that  this  may  be  sufficiently  interposed  between 
its  particles  to  prevent  them  from  touching,  it  is  liable  to 
be  comminuted  into  a  black  or  deep  blue  powder.    Accord- 
ing to  Berzelius,  it  is  in  this  form  that  mercury  exists  in 
blue  ointment.     It  follows  that  the  method  which  has  been 
recommended  for  the  purification  of  this  metal  by  agitating 
it  so  as  to  cause  the  oxidizement  of  the  more  electro-posi- 
tive metal  which  it  may  contain,  is  pregnant  with  the  evil 
that  a  portion  of  the  metal  separates  with  the  resulting 
oxides.     There  is  a  large  proportion  of  mercury  separates 
with  the   lime,  during  the  oxidizement  of  the  radical  of 
this  earth  in  the  amalgam  of  calcium. 

1640.  Properties. — Mercury  is  the  only  metal  which  is 
liquid  at  the  ordinary  temperature  of  the  atmosphere.     In 


MERCURY.  301 

colour  and  brilliancy  it  resembles  and  rivals  silver.  It 
freezes  into  a  malleable  solid  at  — 39°,  and  boils  at  665°. 
From  some  experiments  by  Faraday,  it  would  appear  that 
mercury  vaporizes  to  a  minute  extent,  whenever  the  tem- 
perature of  the  air  is  above  70°.  At  the  temperature  of 
60,  its  specific  gravity  is  13.6;  but  in  freezing,  it  is  in- 
creased to  14.4. 

1641.  Mercurial  compounds  are  all  volatilizable  by  heat; 
and  mercurial  salts,  when  moistened  and  rubbed  upon  cop- 
per, cover  it  with  a  film  of  mercury. 

1642.  It  is  alleged  that  if  a  drop  of  any  liquid  contain- 
ing mercury  be  placed  upon  gold,  and  touched  with  the 
blade  of  a  knife,  or  a  piece  of  iron  wire,  the  mercury  will 
be  precipitated  upon  the  gold. 

Of  the  Alloys  of  Mercury  with  other  Metals,  called 
Amalgams. 

o 

1643.  All  metals  combine  with  mercury,  directly  or  in- 
directly.    Its  compounds  have  the  generic  name  of  amal- 
gams.    In  the  case  of  gold,  silver,  zinc,  lead,  tin,  and  bis- 
muth, the  amalgamation  is  rapidly  effected.      It  is   less 
easily  produced  with  copper,  unless  when  this  metal  sepa- 
rates mercury  from  the  acids.     It  is  difficult  to  unite  mer- 
cury with  platinum,  and  still  more  so  with  iron,  owing, 
probably,  to  the  great  difference  in  fusibility. 

1644.  Mercury  unites  energetically  with  the  metals  of 
the  alkalies.     In  the  case  of  sodium,  a  species  of  combus- 
tion ensues,  so  that  the  mass  becomes  red-hot;  and  when 
sodium  is  thrown  upon  mercury,  it  is  repelled  with  vio- 
lence, and  with  a  disengagement  of  light. 

1645.  The  amalgam  of  potassium  is  an  efficient  instru- 
ment  in  the   evolution  of  the  amalgam  of  ammonium. 
(1112.) 

1646.  The  equivalents  of  mercury,  and  of  its  compounds 
with  oxygen,  chlorine,  and  sulphur,  are  as  follows: — 

Mercury,  equivalent  202 

Protoxide,  1  atom  mercury  with  1  atom  oxygen  210 

Bioxide,  1  „  ,,2  atoms     „  2l'8 

Protochloride,  1  „  „    1  atom  chlorine  238 

Bichloride,  1  „  ,,2  atoms     „  274 

Protosulphide,  1  „  ,,1  atom  sulphur,  218 

Bisulphide,  1  „  ,,2  atoms      „  234 


302  INORGANIC   CHEMISTRY. 

Of  the  Compounds  of  Mercury  with  Oxygen. 

1647.  There  is  still  some  discordancy  in  the  opinions 
and  language  of  chemists  respecting  the  oxides  of  mer- 
cury.  It  has  been  generally  held  that  there  are  two  oxides 
of  this  metal;  one  black,  the  other  red.    According  to  the 
table  of  equivalents  in  the  Appendix,  the  atom  of  mercury 
=  202,  with  one  atom  of  oxygen,  forms  the  black  oxide  or 
protoxide,  =  210,  and  with  two  atoms  of  oxygen  forms  the 
red  oxide,  peroxide,  deutoxide,  or  bioxide,  =  218.     Dr. 
Thomson,  conceiving  the  atom  of  mercury  to  have  only 
half  the  weight  here  assigned  to  it,  considers  the  black 
oxide  as  consisting  of  two  atoms  of  metal,  and  one  of  oxy- 
gen, and  consequently  designates  it  as  a  suboxide.     The 
difference  in   this   case,    therefore,   is  only  hypothetical. 
But  Guibourt  has  advanced  that  there  is  only  one  oxide  of 
mercury,  the  black  oxide  being  composed,   according  to 
him,  of  the  red  oxide  and  metallic  mercury.     Donovan,  on 
the  other  hand,  has  shown  that,  when  a  small  quantity  of 
calomel   is   added  to   a  comparatively  large   quantity  of 
potash,  a  pure  protoxide  or  suboxide  is  obtained. 

1648.  The  protoxide  of  mercury  may  be  obtained  by 
digesting  the  protochloride  with  an  excess  of  potash.   The 
oxygen  and  chlorine  exchange  places,  and  the  chloride  of 
potassium,  and  protoxide  of  mercury  are  formed.     This 
oxide  may  be  precipitated  from  a  solution  of  the  nitrate 
of  the  protoxide,  by  the  addition  of  an  alkaline  solution. 
It  has  likewise  been  supposed  to  be  produced  when  mer- 
cury is  subjected  to  long  continued  agitation,  in  contact 
with  air.     It  is,  however,  alleged  by  Berzelius,  that  the 
black  powder,  thus  obtained,  is  metallic  mercury  in  a  state 
of  extreme   division,    to  which  it  could   not  be  reduced 
without  the  interposition  of  the  oxide,  resulting  from  the 
presence  of  a  more  oxidizable  metal;  that,  when  the  metal 
is  quite  pure,  and  free  from  the  interposition  of  heteroge- 
neous particles,  it  undergoes  no  change  by  agitation  ;  but 
that  if,  under  the  same  circumstances,  it  be  triturated  with 
grease,  gum,  powdered  glass,  or  sand,  it  may  be  reduced 
to  a  black  metallic   powder.     He  conceives  that  all  the 
preparations   made   by  triturating  mercury  with  grease, 
gum,  or  other  viscid  substances,  contain  the  metal  in  a  di- 
vided state,  but  not  oxidized. 

1649.  The  protoxide  of  mercury  is  a  black  powder,  which, 


MERCURY.  303 

by  exposure  to  light,  or  to  the  heat  of  boiling  water,  is 
converted  into  metallic  mercury  and  bioxide. 

1650.  The  bioxide  may  be  procured  by  long  exposure  of 
mercury  to  a  heat  sufficient  to  cause  a  gentle  ebullition, 
the  air  having  free  access.     It  may  likewise  be  obtained 
by  expelling  the  acid  from  the  nitrate  by  heat.     Berzelius 
informs  us,  that,  agreeably  to  the  opinion  of  some  respect- 
able physicians,  it  is  only  when  procured  by  the  former 
method  that  it  is  fit  to  be  used  internally.     He  attributes 
this  difference  to  the  fact  of  its  sometimes  retaining,  when 
obtained  from  the  nitrate,  a  small  portion  of  nitric  acid. 
This  oxide,  when  in  mass,  is  of  a  beautiful  red  colour,  but, 
when  powdered,  assumes  a  yellowish  appearance.     It  is 
decomposed  into  metallic  mercury  and  oxygen  at  a  heat 
a  little  below  redness.     In  water  it  is  slightly  soluble,  and 
its  solution  has  the  property  of  rendering  syrup  of  violets 
green. 

1651.  Both  the  oxides  of  mercury  act  as  bases.     The 
bioxide  forms  with  ammonia  a  fulminating  compound. 

Of  the  Reaction  of  Acids  with  Mercury  and  its  Oxides. 

1652.  When  nitric  acid,  whether  cold  or  hot,  concen- 
trated or  dilute,  is  brought  into  contact  with  mercury,  one 
portion  of  the  acid  is  decomposed,  imparting  oxygen  to  the 
metal ;  the  oxide  thus  formed  being  dissolved  by  the  re- 
mainder of  the  acid.     When  the  metal  is  in  excess,  the 
protoxide  is  principally  formed.     When  the  acid  is  in  ex- 
cess, the  bioxide  predominates.     Usually,  more  or  less  of 
each  oxide  is  formed. 

1653.  Whether  concentrated  or  dilute,  cold  sulphuric 
acid  does  not  react  with  mercury ;  but  when  the  concen- 
trated acid  is  boiled  on  the  metal,  the  phenomena  are  ana- 
logous to  those  which  ensue  in  the  case  of  nitric  acid.   One 
portion  of  the  acid  yields  oxygen  to  the  metal ;  another 
combines  with  the  oxide  thus  created. 

1654.  As  in  the  case  of  nitric  acid,  we  may  have  the 
oxybase  of  mercury  in  the  state  of  bioxide,  or  of  protoxide, 
accordingly  as  the  acid  or  the  metal  is  in  excess,  or  as  the 
time  allowed  for  oxidizement  is  greater  or  less. 

1655.  Each  oxide  of  mercury  forms  three  salts  with 
nitric  acid.     When  washed  with  hot  water,  the  bisulphate 
of  the  bioxide  yields  a  yellow  compound  known  under  the 
name  of  turpeth  mineral,  which,  according  to  a  recent  ana- 


304  INORGANIC  CHEMISTRY. 

lysis  by  Kane,  is  a  subsulphate,  consisting  of  one  atom  of 
neutral  sulphate,  and  two  atoms  of  protoxide,  the  formula 
being  HGO  SO3  +  HGO. 

1656.  Although  in  the  metallic  state,  mercury  has  ge- 
nerally no  reaction  with  acids ;  yet  in  the  state  of  an  oxide, 
it  is  no  doubt  liable  to  be  combined  with  any  of  them. 
About  one  hundred  mercurial  salts  are  mentioned  in  Thom- 
son's Inorganic  Chemistry.  -  With  these  compounds,  with- 
out a  special  motive,  it  would  be  worse  than  useless  for  a 
medical  student  to  burthen  his  memory.  But  it  is  fortunate 
that,  in  this  branch  of  our  knowledge,  we  are  aided  by 
analogy,  and  that  we  are  enabled,  when  we  hear  of  an 
oxacid,   to   infer  that  the  formation   of  a  corresponding 
salt  with  each  oxide  of  mercury  is  possible.     Moreover, 
agreeably  to  the  received  principles  of  chemical  nomen- 
clature, we  are  enabled  to  assign  to  the  compound  thus 
imagined,  a  name  which  would  be  recognised  by  another 
chemist. 

1657.  In  the  metallic  state,   mercury  has  no  reaction 
with  acids,  having  hydrogen  for  their  radical,  called  hydra- 
cids,  by  some  chemists ;  but  which  are,  in  this  book,  de- 
signated as  halohydric,  or  amphydric  acids.  (660.)     Yet, 
excepting  in  the  case  of  the  earths  proper,  it  may  be  as- 
sumed that,  when  any  metallic  oxide  is  presented  to  any  of 
the  hydracids,  water  will  be  formed  by  the  oxygen  of  the 
one,  and  the  hydrogen  of  the  other ;  while  the  metal  and 
basacigen  body  will  unite,  and,  in  a  majority  of  instances, 
the  metal  will  acquire  the  same  number  of  atoms  of  the 
basacigen  body,  as  it  relinquishes  of  oxygen.     It  follows, 
of  course,  that  on  subjecting  a  mercurial  oxide  to  chloro- 
hydric,  bromohydric,  iodohydric,  fluohydric,  cyanhydric, 
sulphydric,  selenhydric,  or  telluhydric  acid,  a  chloride,  bro- 
mide, iodide,  fluoride,  cyanide,  sulphide,  selenide,  or  tel- 
luride,  will  generally,  if  not  universally,  result. 

Of  the  Chlorides  of  Mercury. 

1658.  When  a  solution  of  chloride  of  sodium  and  of 
nitrate  of  the  protoxide  of  mercury  are  mingled,  the  oxy- 
gen of  the  oxide,  and  chlorine  of  the  chloride  exchange 
places;  so  that  protochloride  of  mercury  (calomel)  pre- 
cipitates, while  the  oxygen  and  sodium  uniting,  remain  in 
solution,  and  in  union  with  the  nitric  acid. 

1659.  If  the  solution  of  chloride  of  sodium  be  added  to 


MERCURY.  305 

a  solution  of  the  nitrate  of  the  bioxide,  the  two  atoms  of 
oxygen  in  this  oxide  will  exchange  places  with  the  chlo- 
rine in  two  atoms  of  the  chloride;  so  that  the  mercury  will, 
for  two  atoms  of  oxygen,  acquire  a  like  number  of  atoms 
of  chlorine,  and  be  thus  converted  into  one  atom  of  bi- 
chloride, or  corrosive  sublimate,  which  will  remain  in  solu- 
tion, if  there  be  enough  water  present.  Thus  the  quantity 
of  chlorine  transferred  is  regulated  by  the  quantity  of  oxy- 
gen in  the  oxide  employed;  the  protoxide  producing  the 
protochloride,  the  bioxide  the  bichloride.  (1657.) 

1660.  The  complex  affinity  which  causes  these  changes, 
operates  either  in  the  wet  or  dry  way;  that  is,  whether 
the  substances  be  mixed  in  solution,  or  sublimed  together. 
The  bisulphate  of  the  bioxide  of  mercury  produces  these 
results,  when  sublimed  with  certain  compounds  of  chlo- 
rine, as  chloride  of  sodium  for  instance.     Corrosive  sub- 
limate is  thus  procured;  and,  by  trituration  with  mercury, 
a  second  sublimation,  and  washing  in  boiling  water,  may 
be  converted  into  calomel;  or  the  bisulphate,  by  trituration 
with  a  further  portion  of  the  metal,  being  converted  into 
protosulphate,  forms  calomel  directly  by  sublimation  with 
common  salt. 

1661.  The  process  for  the  manufacture  of  the  proto- 
chloride, has  been  improved  by  causing  its  nascent  vapour 
to  be  mingled  with  steam,  which,  interposing  between  the 
particles,  prevents  them  from  adhering  as  they  condense. 
They  are  thus  obtained  in  a  -state  of  more  minute  divi- 
sion than  could  be  effected  by  trituration,  and  the  aqueous 
particles,  in  condensing,  combine  with  and  remove  any 
particles  of  corrosive  sublimate  which  may  be  generated 
simultaneously  with  those  of  the  calomel.     Calomel  thus 
prepared,  has  been  distinguished  as  Howard's  hydrosub- 
limate. 

1662.  Chlorine  does  not  combine  with  mercury  in  the  in- 
direct mode  abovementioned  only.    A  jet  of  chlorine  burns 
spontaneously  in  mercurial  vapour,  forming  a  bichloride. 

1663.  The  chlorides  of  mercury  may  likewise  be  ob- 
tained by  subjecting  the  oxides  to  chlorohydric  acid;  in 
which  case  the  hydrogen  of  the  acid,  and  oxygen  of  the 
oxide  form  water,  while  the  mercury  and  chlorine  unite; 
the  protoxide  giving  rise  to  the  protochloride,  the  bioxide 
to  the  bichloride,  as  already  explained.  (1657.) 

1664.  The  processes  for  manufacturing  these  important 

39 


306  INORGANIC  CHEMISTRY. 

compounds  of  mercury,  are  very  numerous.  They  have, 
however,  but  one  object — that  of  presenting  chlorine  and 
mercury  to  each  other  in  due  quantities,  and  intimately 
mingled.  When  the  chlorine  is  in  excess,  corrosive  subli- 
mate is  formed;  when  the  metal  predominates,  calomel. 

1665.  The  protochloride  is  white  and  crystalline,  but 
usually  more  compact  than  corrosive  sublimate.     It  is 
tasteless,  inodorous,  and  unalterable  by  exposure  to  the 
atmosphere  if  protected  from  light;  but  by  this  it  is  black- 
ened, and  partially  reduced  to  the  metallic  state.     It  is 
blackened  by  alkaline  solutions,  by  the  generation  of  prot- 
oxide; and  when  the  surface  is  removed,  it  appears  yel- 
low, so  that  a  scratch  made  with  the  nail,  is  productive  of 
a  yellow  streak.     It  is  less  volatile  than  the  bichloride. 
This  chloride  acts  as  a  base. 

1666.  The  bichloride  or  corrosive  sublimate  is  white, 
more  or  less  crystalline,  and  transparent.     It  is  soluble  in 
about  twenty  parts  of  cold  water,  but  more  so  in  hot 
water,  whence  crystals  are  obtained  by  refrigeration.     It 
dissolves  in  two  parts  of  alcohol,  and  in  three  parts  of 
ether,  by  weight.     It  is  not  soluble  either  in  sulphuric  or 
nitric  acid.     On  the  application  of  heat,  it  sublimes  un- 
changed.    When  added  to  an  alkaline  solution  in  excess, 
a  yellow  hydrated  bioxide  of  mercury  precipitates.     The 
proportions  being  reversed,  as  when  an  alkaline  solution  is 
dropped  into  the  solution  of  this  chloride,  a  compound  of 
the  bioxide  and  bichloride  is  precipitated,  which  is  of  a 
brick-red  colour.     Berzelius  designates  this  compound  as 
the  chlorure  mercnrigue  basique,  while  Thenard  gives  it  the 
name  of  bioxido-chlorure.     The  latter  appellation,  changed 
to  oxychloride*  in  order  to  render  it  consistent  with  the 
nomenclature  adopted  in  this  work,  and  more  easy  to  pro- 
nounce, I  shall  employ  for  this,  and  for  analogous  com- 
pounds formed  with  other  metals.t 

1667.  Ammonia  throws  down  from  a  solution  of  the 
bichloride,  a  compound  called  ammoniated  mercury  in  the 

*  I  believe  this  name  is  now  generally  preferred. 

t  This  compound  probably  furnishes  one  among  many  other  instances,  in  which 
an  electro-positive  compound  of  one  basacigen  body,  unites  with  an  electro-negative 
compound  of  another. 

It  might  indeed  be  alleged,  that  in  this  case  the  metal  acts  the  part  of  a  basacigen 
body,  agreeably  to  my  definition,  (628,)  as  it  enters  into  two  compounds,  one  electro- 
negative,  the  other  electro-positive,  which  form  a  tertium  quid.  This  view  of  the 
subject  corroborates  the  remark,  which  I  have  elsewhere  made,  that  nature  has  not 
fitted  her  bodies  for  distinct  classification;  and  that  consequently  there  will  be  cases, 
in  which  some  of  the  bodies  associated  in  one  class,  will  appear  to  belong  to  another. 


MERCURY.  307 

United  States'  Pharmacopoeia,  but  more  generally  known 
as  hydrargyrum  precipitatum  alburn,  or  white  precipitate. 
Some  light,  derived  from  organic  chemistry,  has  lately  led 
to  a  new  view  of  this  preparation,  which  it  will  be  more 
convenient  to  present,  in  treating  of  that  branch  of  the 
science. 

1668.  The  bichloride  of  mercury  has  a  most  nauseous 
metallic  taste,  and  is  a  virulent  poison.    The  best  antidote 
for  it  is  albumen,  which  may  be  given  in  the  form  of  the 
white  of  eggs,  diluted  with  water.     This  chloride,  acting 
as  an  acid,  combines  with  the  chlorides  of  ammonium, 
potassium,  sodium,  barium,  and  magnesium.     As  a  base  it 
combines  with   chlorohydric  acid,  forming   a  crystalline 
compound,  which  effloresces  and  is  decomposed  when  ex- 
posed to  the  air. 

1669.  The  salt,  long  known  under  the  antiquated  appel- 
lation of  sal  alembroth,  and  formed  by  mixing  solutions  of 
sal  ammoniac  and  corrosive  sublimate,  is  now  by  Berzelius 
considered  as  a  double  salt,  and  by  Bonsdorf,  a  chlorohy- 
drargyrate.     This  last  mentioned  name  accords  with  the 
definition  of  acidity  and  basidity  which  I  have  proposed. 

Of  the  Bromides,  Iodides,  Fluorides,  and  Cyanides  of  Mercury. 

1670.  As  respects  the  means  of  their  production,  the  ratio  of  their  con- 
stituent atoms,  and  their  qualities  in  general,  there  is  the  greatest  analogy 
between  the  compounds  formed  by  mercury  with  the  halogen  class.    Hence, 
having  treated  particularly  of  the  chlorides,  I  shall  treat  with  the  utmost 
brevity  of  the  compounds  named  at  the  head  of  this  article. 

1671.  Bromine  forms  two  compounds  with  mercury.    The  protobromide 
is  white,  pulverulent,  and  insoluble.     It  is  obtained  by  the  reaction  of  the 
bromide  of  potassium  with  the  nitrate  of  the  protoxide  of  mercury. 

1672.  The  bibromide  is  formed  by  subjecting  mercury  to  the  action  of 
bromine  and  water.     It  is  soluble,  crystallizable,  fusible,  capable  of  volatili- 
zation, and  colourless.     With  the  alkaline  bromides  it  acts  as  an  acid. 

1673.  The  protiodide  of  mercury  is  obtained  by  the  reaction  of  the 
iodide  of  potassium  with  the  nitrate  of  the  protoxide  of  mercury.    It  is  olive 
coloured,  insoluble  in  water,  and  corresponds  in  composition  with  the  prot- 
oxide. 

1674.  The  biiodide  may  be  procured  by  adding  the  iodide  of  potassium 
to  a  solution  of  the  bichloride  of  mercury.     A  reciprocal  decomposition 
takes  place,  and  the  biiodide  of  mercury  and  the  chloride  of  potassium  are 
formed.     The  biiodide  is  fusible,  volatile,  and  of  a  transcendently  beautiful 
scarlet  colour.     As  an  acid  it  combines  with  the  iodides  of  many  of  the 
earths  and  alkalies,  and  with  the  iodides  of  zinc  and  iron.     As  a  base  it 
unites  with  iodohydric  acid.     It  consists  of  one  atom  of  mercury,  com- 
bined with  two  atoms  of  iodine 


308  INORGANIC  CHEMISTRY. 

1675.  Another  iodide  exists,  containing  less  iodine  than  the  biiodide,  but 
more  than  the  protiodide. 

1676.  Although  cyanogen  does  not  combine  with  mercury  directly,  a 
bicyanide  is  obtained  when  the  bioxide  of  this  metal  is  digested  in  water 
with  Prussian  blue.     I  shall  more  fully  explain  this  process  when  treating 
of  iron. 

1677.  The  employment  of  the  bicyanide  in  the  evolution  of  cyanogen 
and  cyanhydric  acid,  has  already  been  mentioned.  (1296).    The  bicyanide 
of  mercury  forms  combinations  with  the  alkaline  cyanides,  in  which  it  plays 
the  part  of  an  acid. 

1678.  The  fluoride  of  mercury  is  obtained  by  the  action  of  fluohydric 
acid  on  the  bioxide.     It  acts  both  as  an  acid  and  base.     It  is  yellow,  vola- 
tile, and  when  volatilized  in  platinum  or  glass  vessels,  corrodes  them. 
If  subjected  to  water,  it  is  resolved  into  a  soluble  and  an  insoluble  com- 
pound. 

Of  the  Compounds  of  Mercury  with  Sulphur. 

1679.  Agreeably  to  the  list  of  equivalents  near  the  beginning  of  this 
section,  mercury  forms  with  sulphur,  a  protosulphide  and  a  bisulphide. 
When  a  weak  solution  of  the  nitrate  of  the  protoxide  of  mercury  is  im- 
pregnated with  sulphydric  acid,  the  protosulphide  is  produced  in  the  form 
of  a  black  precipitate.     It  appears  to  be  an  unimportant  compound.     The 
protosulphide  acts  as  a  sulphobase.* 

1680.  The  bisulphide  may  be  generated  by  impregnating  with  the  same 
gas  a  solution  of  the  bichloride.     Thus  obtained,  it  resembles  the  protosul- 
phide in  assuming  a  black  colour,  which,  however,  may  be  changed  to  red 
by  sublimation. 

1681.  The  bisulphide  (artificial  cinnabar)  is  procured  in  the  large  way, 
by  fusing  one  part  of  sulphur,  stirring  in  gradually  six  or  seven  of  mercury, 
and  subjecting  the  resulting  black  mass  to  the  process  of  sublimation  in 
close  vessels. 

1682.  KirchofF  procured  cinnabar  by  a  long  continued  trituration  of 
mercury  and  sulphur  with  a  solution  of  caustic  potash,  aided  by  a  gentle 
heat. 

1683.  Bisulphide  of  mercury  is  attacked  neither  by  sulphuric,  nitric 
nor  chlorohydric  acid,  nor  by  caustic  alkaline  solutions ;  but  when  subject- 
ed to  chlorine,   either  in  aqueous  solution  as  in  aqua  regia,  or  in  the 
gaseous  form,  it  is  converted  into  bichloride  of  mercury,  and  bichloride  of 
sulphur. 

1684.  Berzelius  alleges  that  this  bisulphide  performs  the  part  of  a  base 
in  combining  with  the  aeriform  sulphacids.     It  also  forms  compounds  with 
the  bichloride,  bibromide,  biiodide,  and  bifluoride  of  mercury. 

1685.  Equal  parts  by  weight  of  mercury  and  sulphur,  triturated  to- 
gether, form  a  black  mass,  called,  from  its  colour,  Ethiops  mineral,  which 
is  now  considered  as  a  mixture  of  bisulphide  of  mercury  and  sulphur. 

*  Guibourt,  who  has  been  mentioned  as  questioning  the  existence  of  more  than 
one  oxide  of  mercury,  has  alleged  his  disbelief  in  the  existence  of  more  than  one 
mercurial  sulphide ;  the  black  sulphide  being,  in  his  opinion,  a  mixture  of  the  red 
with  the  metal.  Seftstrom  controverts  this  allegation,  and  Thenard,  citing  his 
opinions  and  that  of  Guibourt,  inclines  in  favour  of  those  of  Seftstrom.  Thenard 
alleges  that  at  least  the  protosulphide,  exists  as  a  base,  in  combination  with  sulphides, 
acting  of  course  as  sulphacids  agreeably  to  my  definition.  (631.) 


MERCURY.  309 

Of  the  Phosphurets  of  Mercury. 

1686.  In  its  habitudes  with  mercury,  phosphorus  displays  that  analogy 
with  sulphur  which  is  in  general  so  remarkable.     It  forms,  according  to 
Berzelius,  a  red  and  a  black  phosphuret.     The  latter  results  from  the  diges- 
tion of  bioxide  of  mercury  with  phosphorus  and  water;  the  former,  from 
exposing  phosphorus  to  the  vapours  of 'the  bichloride  of  mercury. 

Experimental  Illustrations. 

1687.  Ebullition  and  distillation  of  mercury.     Its  com- 
pounds with  oxygen  and  sulphur,  exhibited.     Action  of 
nitric  acid  and  of  sulphuric  acid  on  the  metal.     Resulting 
salts,  subjected  to  hot  water.     Black  oxide  and  red  oxide, 
severally  dissolved  in  nitric  acid.     Chlorohydric  acid  pre- 
cipitates calomel  from  the  one,  but  occasions  no  precipitate 
in  the  other.     Fixed  alkalies  and  alkaline  earths  produce 
a  black  precipitate  in  the  nitrate  of  the  black  oxide  or  prot- 
oxide, an  orange  precipitate  in  the   nitrate  of  the  red 
oxide  or  bioxide.     Similar  results  obtained  by  adding  them 
to  calomel  and  corrosive  sublimate ;  the  former  giving  the 
black,  the  latter  the  red  oxide.     Hydrargyrum  precipita- 
tum  album,  precipitated  from  solution  of  bichloride  by  am- 
monia.   Solutions  of  the  different  mercurial  oxides  precipi- 
tated by  iodide  of  potassium.     Inflammation  of  chlorine 
with  mercurial  vapour.    Explosion  of  fulminating  mercury. 
Diversity  of  precipitates  produced  by  adding  bichloride  to 
an  excess  of  alkali,  or  adding  the  latter  to  an  excess  of  bi- 
chloride. (1666.) 

Combustion  of  Mercury  with  Chlorine. 

1688.  This  experiment  may  be  performed  by  means  of  the  apparatus  represented 
by  the  following  cut.     Let  there  be  a  glass  globe,  furnished  with  a  neck  and  tubu- 
lure,  and  holding  about  two  gallons  of  chlorine.    Into  the  neck,  let  a  trumpet-shaped 
tube,  B,  reaching  to  the  bottom,  be  fastened  air-tight  by  means  of  a  cork. 

1689.  Let  another  tube,  about  fifteen  inches  in  length,  and  tapering  towards  one 
end,  so  as  to  form  a  capillary  orifice,  be  fastened,  at  the  other  end,  into  the  lateral 
tubulure  of  the  globe.     Provide  a  globular  receiver,  R,  with  a  neck  on  one  side,  and 
a  perforation  on  the  other,  opposite  the  neck. 

1690.  Let  the  lower  part  of  this  vessel  be  occupied  by  about  a  gill  of  mercury,  and 
exposed  to  a  chauffer  of  coals,  so  as  to  fill  the  whole  cavity  of  the  vessel  with  the 
vaporized  metal.     Under  these  circumstances,  introduce  the  pipe,  D,  proceeding  from 
the  lateral  tubulure,  into  the  neck  of  the  receiver,  so  that  the  capillary  orifice  may  be 
near  the  perforation  ;  and   immediately  afterwards  pour  chlorohydric  acid  into  the 
tube,  B.     This  will  subject  the  chlorine  to  pressure  without  absorbing  it,  and  conse- 
quently cause  it  to  escape  in  a  jet  from  the  capillary  orifice  in  the  pipe.     Hence, 
mingling  with  the  vaporized  mercury,  it  will  produce  a  feebly  luminous  flame. 

1691.  Instead  of  using  the  globe  and  its  appendages,  I  have,  in  a  majority  of 
instances,  employed  a  tubulated  retort,  with  a  long  narrow  beak,  for  the  production 
of  the  jet  of  chlorine.    The  retort  being  sufficiently  supplied  with  manganese,  and  a 


310  INORGANIC  CHEMISTRY. 


glass  funnel  with  a  cock  being  fastened  into  the  tubulure,  as  much  chlorohydric 
acid  is  allowed  to  enter  through  the  funnel,  as  will  generate  a  sufficient  quantity  of 
chlorine  to  produce  a  jet  from  the  capillary  orifice,  in  which  the  beak  of  the  retort 
is  purposely  made  to  terminate.  The  beak  of  the  retort  being  made  to  occupy  the 
place  of  the  tube,  represented  in  the  figure  as  proceeding  from  the  globe,  the  expe- 
riment is,  in  other  respects,  the  same  as  that  above  described. 

1692.  Since  this  engraving  was  made,  for  the  purpose  of  supplying  chlorine,  I 
have  found  my  self-  regulating  reservoir  of  chlorine,  to  render  the  performance  of 
this  experiment  more  convenient  and  less  precarious  than  the  apparatus  above  re- 
presented. (788,  975.) 


SECTION  V. 
OF  COPPER. 

1693.  Copper  is  occasionally  found  in  nature  in  the  me- 
tallic state;  also  in  those  of  oxide,  carbonate  and  sulphide. 
It  is  obtained  principally  from  the  sulphide.     The  sulphide 
being  acidified  and  volatilized,  and  the  metal  oxidized  by 
torrefaction,  the  resulting   oxide  is  decomposed   by  heat 
and  charcoal. 

1694.  The  copper  of  commerce  contains,  according  to 
Berzelius,  a  minute  portion  of  sulphur  and  carbon.      It 
may  be  purified  by  solution  in  concentrated  and  boiling 
chlorohydric  acid,  and  subsequent  precipitation  by  a  bright 
plate  of  iron. 

1695.  Properties.  —  The  lustre   and  peculiar  colour  of 
this  metal*  are  too  well  known  to  need  description.     Ex- 


COPPER.  311 

cepting  titanium,  it  is  the  only  red  metal.  It  is  very  mal- 
leable and  ductile,  and  next  to  iron  in  tenacity.  It  fuses 
at  a  white  heat.  Alloyed  with  a  small  quantity  of  tin, 
copper  forms  bronze;  with  a  larger  quantity,  bell  metal. 
Fused  with  zinc,  or  subjected  to  the  vapour  of  this  metal, 
as  evolved  from  calamine  when  heated  with  charcoal,  it  is 
converted  into  brass. 

1696.  If  a  current  of  ammoniacal  gas  be  passed  over 
copper,  heated  to  bright  redness  in  a  tube,  the  gas  is  de- 
composed, and  the  copper  becomes  brittle,  although  its 
weight  is  but  slightly,  if  at  all  increased.     This  change  is 
supposed  to  be  due  to  a  different  aggregation  of  the  parti- 
cles of  the  copper,  induced  by  the  formation  and  subse- 
quent decomposition  of  a  nitruret  of  copper. 

1697.  The  blade  of  a  knife,  or  any  bright  piece  of  iron 
or  steel,  is  a  test  for  copper  in  solution;  as  a  film  of  this 
metal  will  be  precipitated  upon  the  iron  or  steel  and  com- 
municate  to   it   the   appearance   of  copper.     Ammonia, 
when  added  in  excess,  produces  a  blue  colour  in  water 
containing  a  very  minute  quantity  of  copper,  (523,  &c.) 
but  I  have  ascertained  that  it  requires  twice  as  much  cop- 
per to  produce  a  blue  tinge  with  ammonia,  as  to  produce 
with  the  cyanoferrous  acid  of  the  cyanoferrite  of  potas- 
sium, the  appropriate  hue  of  the  cyanoferrite  of  copper, 
which  is  a  peculiar  rich  reddish-brown.     With  this  test  I 
have  detected  copper  in  the  rain  water,  proceeding  from 
the  spout  of  a  copper  roof. 

1698.  Phosphorus  combines  with  copper  in  various  pro- 
portions, forming  unimportant  compounds.     When  present 
in  small  quantity,  it  has  an  effect  upon  this  metal  similar 
to  that  which  carbon  has  on  iron,  rendering  the  copper 
hard  enough  for  cutting  instruments.     Carbon  and  silicon 
both  combine  with  copper. 

1699.  The  specific  gravity  of'copper  is  nearly  9. 

1700.  The  equivalents  of  copper,  and  of  its  compounds 
with  oxygen,  chlorine,  and  sulphur,  are  as  follows: — 

Copper,                                       .  32 

Red  or  dioxide,  2  atoms  copper  with  1  atom  oxygen,  72 

Black  or  protoxide,  1  atom       „               1  atom       „  40 

Peroxide,  1  atom  copper  with  2  atoms  oxygen,  48 

Bichloride,  2  atoms      „                1  atom  chlorine,  100 

Protochloride,  1  atom       „                I  atom       „  68 

Disulphide,  2  atoms     „               I  atom  sulphur,        ,    -  80 

Protosulphide,  1  atom      „               1  atom       „  48 


312  INORGANIC  CHEMISTRY. 

Of  the  Compounds  of  Copper  with  Oxygen. 

1701.  There  are  three  oxides  of  copper,  a  dioxide,  a 
protoxide,  and  a  peroxide. 

1702.  Every  one  is  familiar  with  the  appearance  of  the 
dioxide;  since  it  forms  the  dull  red  exterior  coating  of 
copper,  as  it  comes  to  us  from  the  manufacturer.    When 
this  oxide  is  subjected  to  liquid  chlorohydric  acid,  a  double 
decomposition  ensues,  and  water  and  a  dichloride  of  copper 
are  formed,  the  latter  remaining  in  solution.     Subjected  to 
nitric  acid,  the  dioxide  is  converted  into  protoxide  by  one 
portion  of  the  acid,  and  dissolved  by  the  other.     By  ig- 
niting the  protoxide  with  metallic  copper,  the  anhydrous 
dioxide  is  produced.     On  mingling  solutions  of  potash  and 
of  the  dichloride,  an  orange-coloured  hydrate  of  the  diox- 
ide precipitates.     It  is  difficult  to  wash  and  dry  this  com- 
pound without  partially  converting  it  into  protoxide. 

1703.  The  protoxide  of  copper  is  of  a  brownish-black 
colour.     It  is  formed  upon  sheet  copper,  when  exposed  to 
a  bright  red-heat  with  access  of  air.     To  obtain  it,  how- 
ever, Thenard  recommends  that  the  nitrate  or  sulphate  be 
intensely  ignited  in  a  stoneware  retort,  by  which  means 
the  acid  is  volatilized,  and  the  protoxide  remains.     This 
oxide  is  formed  when  copper  is  dissolved  in  nitric  or  sul- 
phuric acid,  and  enters  into  combination  with  them,  form- 
ing a  nitrate,  or  sulphate. 

1704.  Thenard  alleges  that  it  is  soluble  in  ammonia, 
only  when  combined  with  water  or  some  acid;  and  that  it 
is  insoluble  in  the  fixed  alkalies,  whether  hydrous  or  an- 
hydrous. 

1705.  That  the  fixed  alkalies  promote  its  oxidizement, 
is  evident;  since  sheet  copper,  or  brass,  moistened  with 
alkaline  solutions,  always  becomes  green  in  the  air.     I 
think  it  probable,  that  carbonic  acid  co-operates  in  pro- 
ducing this  result. 

1706.  The  peroxide  of  copper  is  formed  by  mingling 
the  bioxide  (deutoxide)  of  hydrogen  with  a  weak  solution 
of  nitrate  of  copper,  and  adding  just  enough  alkali  to  de- 
compose all  the  nitrate.     These  conditions  being  realized, 
a  brownish-yellow  gelatinous  mass  subsides,  which,  after 
being  washed  upon  a  filter  with  cold  water,  and  dried  in 
the  vacuum  of  an  air  pump  over  sulphuric  acid,  forms  the 
peroxide.     This  oxide  has  no  taste  or  smell. 


COPPER.  313 

1707.  The  dioxide  of  copper  acts  feebly  as  a  base,  the 
protoxide  energetically,  and  the  peroxide  plays  the  part 
neither  of  a  base  nor  of  an  acid. 

1708.  Nitric  acid  diluted  nearly  to  the  specific  gravity 
of  1.2,  protoxidizes  and  dissolves  copper,  producing  a  blue 
solution,  which  yields,  by  evaporation,  elegant  blue  crys- 
tals.    The  ignition  which  ensues  when  these  crystals  are 
pulverized,  moistened,  and  rolled  up  in  tinfoil,  has  been  ad- 
duced as  an  exemplification  of  the  influence  of  water  in 
promoting  chemical  reaction.  (829.) 

1709.  The  crystals  of  nitrate  of  copper  are  of  a  deeper 
blue  than  those  of  the  sulphate,  and  are  deliquescent.     At 
a  moderate  temperature,  these  crystals  fuse,  and  lose  a  part 
of  their  water  of  crystallization. 

1710.  Sulphuric  acid,  boiled  on  copper,  oxidizes  and  dis- 
solves it  without  heat,  as  nitric  acid  does.     The  resulting 
compound  forms  the  blue  crystals  of  the  sulphate,  called  in 
commerce  blue  vitriol  or  blue  stone.  (494.) 

1711.  A  compound  is  obtained  by  triturating  sulphate 
of  copper  with  carbonate  of  ammonia,  called  cuprum  am- 
moniatum  (ammoniated  copper)  in  the  Pharmacoposias. 

1712.  This  contains  the  ammoniacal  sulphate  of  copper, 
with  some  portion  of  the  carbonate  undecomposed.  It  may 
be  a  mixture  of  ammoniacal  sulphate,  and  ammoniacal 
carbonate  of  copper.     It   is  designated  as  ammoniated 
copper  in  the  United  States'  Dispensatory;  and  the  authors 
allege  that  there  is   some    obscurity  as  to  the   mode  in 
which  its  ingredients  are  associated.     It  has  been  stated 
above,  that  the  protoxide  of  copper  is  not  soluble  in  am- 
monia, unless  when  united  with  water  acting  as   hydric 
acid,  or  with  some  other  substance  capable  of  performing 
the  part  of  an  acid.     Berzelius  mentions  that  the  protox- 
ide of  copper  may  be  kept  in  a  bottle  containing  liquid 
ammonia,  without  tinging  it  blue ;  but  that  the  introduc- 
tion of  only  a  few  drops  of  any  ammoniacal  salt,  the  car- 
bonate for  instance,  causes  the  well  known  striking  blue 
colour  of  the  cupreous  solution,  formerly  called  aqua  sap- 
phirina.     He  also  alleges  that  cuprum  ammoniatum  con- 
tains the  ingredients  in  such  proportion,  that  the  alkali 
saturates  twice  as  much  acid  as  the  copper. 

40 


314  INORGANIC  CHEMISTRY. 


Of  the  Compounds  of  the  Oxides  of  Copper  with  Acetic 

Acid. 

1713.  The  oxides  of  copper  form  salts  with  almost  every 
acid,  whether  mineral  or  vegetable.     Among  these,  none 
are  better  known  than  its  combinations  with  acetic  acid,  of 
which  one  is  designated   in   commerce  as  verdigris,  the 
other  as  crystals  of  Venus. 

1714.  Crude  verdigris  is  a  mixture  of  neutral  acetate 
and  subacetate  of  copper,  with  some  impurities. 

1715.  The  neutral  acetate  crystallizes  readily,  and  in  the 
crystalline  form  has  received  the  name  of  crystals  of  Ve- 
nus ;  Venus  having  been  one  of  the  names  given  to  cop- 
per by  the  old  chemists. 

1716.  The  subacetate  consists  of  one  atom  of  acid  with 
two  of  protoxide,  while  the  neutral  acetate  consists  of  one 
atom  of  each  constituent. 

1717.  The  salts  of  the  protoxide  of  copper  are  all  of  an 
intensely  blue  or  green  colour.     This  does  not  appear  to 
be  true  in  the  case  of  the  dioxide ;  since,  according  to  Ber- 
zelius,  when  verdigris  is  subjected  to  heat,  colourless  crys- 
tals of  the  acetate  of  the  dioxide  sublime,  so  as  nearly  to 
fill  the  beak  of  the  retort.     Thenard  alleges  that  when  the 
hydrated  dioxide  is  subjected  to  liquid  ammonia,  a  colour- 
less solution  of  it  results. 

Of  the  Compounds  of  Copper  with  the  Halogen  Class. 

1718.  A  chlorohydrate  of  the  dichloride  of  copper,  acting  as  a  chlorobase,  may  be 
prepared  by  the  action  of  chlorohydric  acid  on  a  mixture  of  the  protoxide  of  copper, 
and  finely  divided  metallic  copper.     From  this  chlorohydrate,  the  dichloride  may  be 
precipitated  by  water.     It  is  likewise  produced  by  heating  the  protochloride  in  close 
vessels,  by  which  one-half  of  the  chlorine  is  expelled.     This  chloride  may  also  be 
obtained  from  the  protochloride,  by  digestion  in  chlorohydric  acid  with  copper  shreds 
or  filings.     When  thus  evolved,  it  subsides  in  crystals,  which  can  only  be  dried  in 
vacuo  over  sulphuric  acid ;  as  in  the  air  they  are  converted  into  a  compound  of  the 
dioxide  with  the  protochloride,  forming  of  course  an  oxychloride. 

1719.  The  dichloride  is  soluble,  crystallizable,  and  fusible  by  heat.     It  consists  of 
two  atoms  of  copper,  and  one  of  chlorine. 

1720.  The  protochloride  may  be  formed  either  by  the  reaction  of  chlorohydric  acid 
with  the  protoxide,  or  by  the  combustion  of  copper  wire  or  leaves  in  chlorine.     It  is 
of  a  bluish-green  colour,  and  an  astringent  taste.     It  is  crystallizable,  fusible,  and 
decomposable  by  heat.  This  chloride  attracts  moisture,  and  is  very  soluble  in  water. 
Characters  written  with  a  solution  of  it,  remain  invisible  until  heated,  when  they 
become  yellow.     It  constitutes,  of  course,  a  species  of  sympathetic  ink.     The  proto- 
chloride  acts  as  an  acid  with  the  chlorides  of  potassium  and  ammonium,  and  with 
other  chlorobases,  forming  with  them  chlorocuprates. 

1721.  No  compound  of  copper  with  bromine  is  mentioned  by  Berzelius  or  The- 
nard.     Those  formed  with  iodine  appear  feeble  and  unimportant.     With  fluorine, 
copper  forms  two  compounds,  a  protofluoride,  and  a  perfluoride.     The  protofluoride 
acts  as  a  base,  the  perfluoride  both  as  a  base  and  an  acid.  Cyanogen  enters  into  com- 
bination with  copper  in  two  different  proportions. 


LEAD.  315 

Of  the  Compounds  of  Copper  with  Sulphur  and  Selenium. 

1722.  A  disulphide  of  copper  may  be  produced  by  the  fusion  of  the  metal,  or  its 
oxide  with  sulphur.     It  is  found  pure  in  nature,  and  likewise  combined  in  definite 
proportions  with  the  sulphides  of  antimony,  arsenic,  bismuth,  and  iron,  in  which 
case  the  sulphur  is  usually  divided  equally  between  the  metals.     Berzelius  alleges 
this  sulphide  to  be  a  powerful  sulphobase.   Yet,  in  its  combination  with  the  sulphide 
of  iron,  it  cannot  be  supposed  to  act  as  a  base,  as  iron  is  more  electro-positive  than 
copper.     The  affinity  between  the  last  mentioned  sulphides  is  so  energetic,  that  the 
resulting  sulphocuprate  of  iron  cannot  be  decomposed  by  the  united  action  of  carbon 
and  a  fixed  alkali. 

1723.  Protosulphide  of  copper  is  formed  when  this  metal  is  precipitated  from  its 
solutions  by  sulphydric  acid. 

1724.  Copper,  by  fusion  with  various  sulphides  of  the  alkalifiable  metals,  is  made 
to  unite  with  several  proportions  of  sulphur,  but  the  resulting  compounds  are  unim- 
portant. 

1725.  The  union  of  copper  with  selenium  is  productive  of  heat  and  light;  in  which 
respect,  as  in  others,  the  analogy  between  selenium  and  sulphur  is  sustained.     The 
resulting  compound  is  a  diselenide.     It  is  found  in  nature,  but  does  not  appear  to 
have  any  interesting  properties.     A  protoselenide  is  formed  when  copper  is  precipi- 
tated by  selenhydric  acid. 

Experimental  Illustrations. 

1726.  Solution  of  copper  in  nitric  acid,  and  its  precipi- 
tation by  iron.     Effects  of  ammonia ;  also  of  cyanoferrite 
of  potassium,  on  solutions  of  copper.     Crystals  of  the 
sulphate,  nitrate,  acetate,  and  subacetate,  exhibited ;  also 
their  solutions.    Exhibition  of  the  protoxide,  and  of  copper 
sheets  superficially  dioxidized. 

SECTION  VI. 

OF  LEAD. 

1727.  Lead  is  found  in  nature,  in  union  with  sulphur  and  with  oxygen, 
and  likewise  united,  in  the  state  of  an  oxybase,  severally  with  chromic, 
sulphuric,  phosphoric,  molybdic,  carbonic,  and  arsenic  acids. 

1728.  Lead  is  procured  chiefly  from  the  native  sulphide,  known  among 
miners  and  mineralogists  under  the  name  of  galena,  which  is  the  most  abun- 
dant and  prolific  of  its  ores.    The  metal  is  liberated  from  galena  by  exposing 
it  to  the  flame  of  a  reverberatory  furnace,  which,  oxidizing  and  expelling  the 
sulphur,  liberates  the  lead,  partially  in  the  state  of  oxide,  principally  in  the 
metallic  state.     The  protoxide  of  this  metal  in  a  semivitrified  state,  called 
litharge,  is  largely  obtained  in  the  process  of  cupellation,  already  described 
as  the  means  of  procuring  silver  from  argentiferous  galena,  or  from  alloys 
in  which  it  exists  in  union  with  more  oxidizable  metals.  (1612.) 

1729.  From  any  of  its  oxides,  the  metal  is  easily  obtained  by  heat  and 
charcoal. 

1730.  In  the  small  way,  a  great  majority  of  its  combinations  will  yield  a 
metallic  globule,  by  exposure,  on  charcoal,  to  the  deoxidizing  or  carbo- 
naceous flame  of  the  blowpipe. 


316  INORGANIC  CHEMISTRY. 

1731.  Properties. — The  colour,  lustre,  and  malleability  of  lead  are  well 
known.     It  fuses  at  about  600°  F.     Its  specific  gravity  is  11.352.     In 
large  masses  it  is  pre-eminently  ductile,  as  it  may  be  drawn  into  pipes  of 
four  inches  bore;  but  it  is  too  deficient  in  tenacity  to  be  drawn  into  fine 
wire.    It  is  very  useful  to  chemists,  being  employed  to  construct  the  cham- 
bers and  vessels  used  in  the  manufacture  of  sulphuric  acid,  of  chlorine, 
and  of  the  bleaching  and  disinfecting  salts. 

Of  the  Compounds  of  Lead  with  Oxygen. 

1732.  The  following  are  the  only  known  compounds  of 
lead  with  oxygen,  with  equivalents  of  the  metal,  and  of 
those  oxides: — 

Dioxide,  or  dross,  probably     2  atoms  lead,  208 

1  atom  oxygen,  8 

216 

Protoxide,  1  atom  lead,  104 

1  atom  oxygen,  8 

112 

Bioxide,  1  atom  lead,  104 

2  atoms  oxygen,          16 

120 

Red  oxide,  or  minium,  3  atoms  lead,  312 

4  atoms  oxygen,          32 

344 

1733.  The  protoxide  of  lead,  as  we  find  it  in  the  shops 
under  the  appellation  of  litharge,  is  of  a  yellow  colour 
when  in  mass,  but  reddish-yellow  when  pulverized.    In  the 
pulverulent  form  it  is  known  in  commerce  by  the  name  of 
massicot.     It  appears  to  be  soluble  in  pure  water,  but  is 
rendered  insoluble  by  the  presence  of  the  smallest  quantity 
of  chloride  of  sodium  or  of  any  earthy  matter.     The  prot- 
oxide of  lead  acts  both  as  an  acid  and  a  base.     In  the  lat- 
ter capacity,  it  unites  with  the  more  powerful  acids;  in 
the  former,  with  the  earths  and  alkalies. 

1734.  When  the  protoxide  of  lead  is   powdered  and 
heated  nearly  to  redness,  and  then  suffered  to  cool  slowly, 
it  is  converted  into  a  substance  called  minium  or  red  lead, 
which  is  largely  consumed  as  one  of  the  materials  of  flint 
glass.     Formerly  minium  was  considered  as  a   distinct 
oxide,  and  to  this  view  of  its  composition  Berzelius  in- 
clines.    Thenard  alleges,  upon  the  authority  of  experi- 
ments made  by  Dumas,  that  it  consists  of  three  atoms  of 
lead  united  to  four  of  oxygen,  and  infers  that  it  is  a  com- 
pound of  one  atom  of  the  bioxide,  and  two  of  the  protoxide. 


LEAD.  317 

1735.  When  minium  is  exposed  to  a  red  heat,  it  evolves 
oxygen,  and  is  converted  into  the  protoxide. 

1736.  The  bioxide  of  lead  is  obtained  by  the  action  of 
nitric  acid  on  minium.     If  minium  be  a  sesquioxide,  one 
portion  of  it  yields  half  of  an  equivalent  of  oxygen  to  an- 
other portion,  and  forms  a  bioxide,  while  it  passes  to  the 
state  of  protoxide,  and  is  taken  up  by  the  acid.    But  if  the 
opinion  of  Thenard  and  Damas  be  correct,  it  must  be  in- 
ferred that  nitric  acid  dissolves  the  protoxide,  and  thus  ex- 
tricates the  bioxide  previously  existing  in  the  mass. 

1737.  The  bioxide  is  of  a  flea-colour,  and  is  convertible 
by  heat,  first  into  minium,  and  then  into  protoxide.    When 
triturated  with  sulphur,  inflammation  ensues.     According 
to  Thenard,  this  oxide  never  acts  as  a  base,  and  but  sel- 
dom as  an  acid. 

1738.  Berzelius  alleges  that  the  gray  pellicle  or  dross, 
which  forms  on  the  surface  of  lead  when  exposed  to  the 
air,  and  which  accumulates  in  greater  quantities  when  the 
metal  is  heated,  is  a  dioxide  of  lead.     He  also  states  that 
this  oxide  may  be  obtained  by  the  decomposition  of  oxalate 
of  lead  by  heat.    Some  recent  experiments  of  Mr.  Boussin- 
gault  tend  to  confirm  this  opinion. 

1739.  The  habitudes  of  lead  with  nitric,  sulphuric,  and 
chlorohydric  acid,  are  so  analogous  to  those  of  mercury 
with  the  same  acids,  that  I  do  not  deem  it  necessary  to  do 
more  than  point  out  the  analogy;  at  the  same  time  men- 
tioning that,  in  the  case  of  lead,  no  compounds  are  formed 
by  oxacids  with  any  oxide  besides  the  protoxide;  and  that  the 
resulting  compounds  have  an  insolubility  more  marked  and 
invariable.     Of  all  the  important  acids,  only  nitric  and 
acetic  acid  form  soluble  compounds  with  lead.     Conse- 
quently, as  in  any  mixture,  those  ingredients  which  form 
insoluble  combinations,  always  exercise  a  superior  affinity, 
it  follows  that,  from  its  solutions,  this  metal  will  be  preci- 
pitated by  any  of  the  important  salts,  excepting  the  nitrates 
or  acetates.     Thus  it  will  be  precipitated  by  sulphates, 
phosphates,  carbonates,  borates,  oxalates,  chromates,  ar- 
seniates,  arsenites,  tartrates,  citrates,  mallates,  meconates, 
benzoates;  also  by  any  of  the  soluble  compounds  of  the 
halogen  bodies,  or  any  of  the  amphydric  or  halohydric 
acids.  (860.) 


318  INORGANIC  CHEMISTRY. 

x 

Of  the  Compounds  of  the  Protoxide  of  Lead  with  Acetic 

Acid. 

1740.  Lead  is  oxidized  and  dissolved  by  acetic  acid, 
and  forms  the  acetate,  called  in  commerce  sugar  of  lead. 
This  name  was  given  to  the  acetate  of  lead  in  consequence 
of  its  taste,  which  is  sweet  and  astringent.     It  is  crystalli- 
zable,  soluble  in  water,  and  decomposable  by  heat. 

1741.  The  acetate  of  lead,  consisting  of  one  atom  of 
oxide,  and  one  atom  of  acetic  acid,  by  digestion  with  the 
protoxide,  whether  in  the  form  of  litharge  or  of  massicot, 
may  talke  either  one  or  two  additional  atoms  of  oxide, 
forming  a  diacetate  consisting  of  two  atoms  of  oxide  and 
one  of  acid,  or  a  triacetate,  consisting  of  three  atoms  of 
oxide  and  one  of  acid. 

1742.  By  boiling  a  solution  of  the  acetate  upon  an 
excess  of  the  protoxide,  a  hexacetate  may  be  obtained,  con- 
sisting of  six  atoms  of  oxide  and  one  of  acid.     This  com- 
pound may  be  produced  also,  by  decomposing  the  acetate 
by  an  excess  of  ammonia.     It  forms,  when  dried,  a  white 
powder,  slightly  soluble  in  boiling,  but  insoluble  in  cold 
water. 

1743.  Goulard's   extract,  of  which  one  "fluidrachm" 
agreeably  to  the  U.  S.  Pharmacopoeia,  is  to  be  added  to  a 
pint  of  distilled  water  to  make  lead-water,  is  usually  con- 
sidered as  a  diacetate,  and  called  the  subacetate ;  but  from 
the  formula,  it  must  be  evident  that  it  may  contain  enough 
oxide  to  make  it  partially,  if  not  wholly,  a  triacetate. 

1744.  It  appears  to  me  that  medical  practitioners,  if 
not  ignorant  of  the  difference  which  exists  in  composition 
between  these  acetates,  are  too  inattentive  to  the  possible 
diversity  of  their  effects. 

1745.  When  an  acetate,  containing  more  than  the  pro- 
portion of  one  atom  of  oxide  to  one  of  acid,  is  brought 
into  contact  with  carbonic  acid  gas,  a  precipitate  ensues 
of  carbonate  of  lead.    Hence  lead- water  may  be  used  as  a 
test  for  carbonic  acid,  producing  results  on  breathing  into 
it,  or  upon  adding  it  to  a  solution  of  any  carbonate,  analo- 
gous to  those  produced  by  lime-water  under  like  circum- 
stances. 

Of  Carbonate  of  Lead. 

1746.  When  exposed  to  the  fumes  of  vinegar,  which 
consist  of  acetic  acid  and  carbonic  acid  gas,  lead  is  oxi- 


LEAD.  319 

dized  by  the  acetic  acid,  and  combines  with  the  carbonic 
acid,  forming  ceruse,  or  the  white  lead  of  commerce. 

1747.  According  to  Thenard,  the  best  process  for  ob- 
taining the  carbonate  of  lead,  is  to  pass  carbonic  acid 
through  a  solution  of  the  diacetate.  Half  the  lead  is  preci- 
pitated in  the  state  of  carbonate,  and  the  remainder  con- 
tinues in  solution  as  an  acetate.  The  solution  /)f  acetate 
is  reduced  to  a  diacetate  by  boiling  it  with  oxide  of  lead, 
and  subjected  to  carbonic  acid  as  before.  In  this  way  car- 
bonate of  lead  of  the  best  quality  is  procured,  with  com- 
paratively little  waste  of  the  acetic  acid.  Carbonate  of 
lead  is  found  in  nature. 

Of  the  Compounds  of  Lead  with  the  Halogen  Class. 

1743.  The  analogy  between  the  habitudes  of  lead  and  mercury  with  acids,  alluded 
to  above,  is  not  greater  than  that  which  exists  between  their  habitudes  with  the  halo- 
gen bodies.  Analogous  reciprocal  decompositions  ensue,  whether  solutions  of  the 
soluble  oxysalts  of  lead  or  mercury  be  mingled  with  solutions  of  chlorides,  bromides, 
iodides,  fluorides,  or  cyanides  of  the  alkalifiable  metals. 

1749.  The  chloride  of  lead  is  white,  crystallizable,  soluble  in  thirty  times  its  weight 
of  water,  and  has  a  sweet  and  astringent  taste.  When  exposed  to  a  red  heat  it  melts, 
and  forms  a  mass  formerly  called  plumbum  corneum,  from  its  resemblance  to  horn. 
If  the  heat  be  pushed  to  redness,  and  the  access  of  air  be  permitted,  the  chlorine  is 
partially  volatilized ;  and  the  remainder  is  found  to  constitute  an  oxychloride.     Seve- 
ral other  oxychlorides  exist,  containing  the  oxide  of  lead,  united  to  the  chloride  in 
various  proportions.     One  of  these  is  found  native  in  England. 

1750.  The  bromide,  iodide,  fluoride,  and  cyanide  of  lead,  which  may,  as  abovemen- 
tioned,  be  generated  by  means  analogous  to  those  by  which  the  chloride  is  obtained, 
are  of  too  little  practical  importance  to  make  it  expedient  to  notice  them  particularly. 

1751.  The  fluoride  acts  as  a  fluobase,  the  cyanide  as  a  cyanobase.     The  former 
combines  with  the  fluacids  of  boron  and  silicon,  the  latter  with  cyanoferrous  (fer- 
roprussic)  acid.  (1299,  &c.) 


s      Of  the  Compounds  of  Lead  with  Sulphur  and  Selenium. 

1752.  Sirfphuj  forms  three  .compounds  with  lead,  a  disulphide,  a  protosulphide, 
and  a  persulphide.     Of  thage;,  the  only  compound  which  I  deern  it  proper  to  notice, 
is  the  protosulphide,  which  "has  already  been  adverted  to  as  the  principal  ore  of  lead, 
called  galena.    This  sulphide  may  be  formed  artificially  by  heating  lead  and  sulphur 
together.     The  protosulphide  of  lead  is  tasteless,  inodorous,  indecomposable  by  heat, 
and  less  fusible  than  lead.     It  acts  as  a  sulphobase,  and  is  composed  of  one  atom  of 
lead,  united  to  one  atom  of  sulphur. 

1753.  The  selenide  of  lead  may  be  procured  by  exposing  lead,  mingled  with  sele- 
nium, to  heat.     When  thus  obtained  it  is  gray,  but  by  friction  it  becomes  polished 
and  white  like  silver.     It  is  found  in  nature. 

/ 

Experimental  Illustrations. 

1754.  Solution  of  lead  in  nitric  acid.  Its  solutions  pre- 
cipitated by  sulphates,  chlorides,  phosphates,  and  chro- 
mates.  Also  by  sulphydric  acid.  Precipitation  of  carbonate 
of  lead  from  the  subacetate  by  the  carbonic  acid  of  the 
breath.  Galena  decomposed  by  the  blowpipe  flame. 


320  INORGANIC  CHEMISTRY. 

SECTION   VII. 

OF  TIN. 

1755.  This  metal  is  found  in  the  state  of  oxide,  and  in  that  of  sulphide. 
The  sulphide  is  rare,  and  contains  much  copper.     The  ore  of  tin,  which  is 
the  principal  ^ource  of  the  metal,  is  the  bioxide  which  is  reduced  by  heat 
and  charcoal.     Tin  is  sold  in  commerce  under  the  name  of  block  tin,  to 
distinguish  it  from  tinned  iron  plates,  vulgarly  called  tin. 

1756.  Properties. — The  colour  and  lustre  of  tin  may  be  seen  in  uten- 
sils newly  made  of  tinned  iron.     It  is  very  malleable  and  ductile;  tinfoil 
being  only  p^-th  of  an  inch  thick.     Tin  tarnishes  slightly  by  exposure  to 
the  air.     It  is  distinguished  by  producing  a  peculiar  crackling  noise,  when 
its  ingots  are  bent  to  and  fro.     It  melts  at  442°  F.     Its  specific  gravity  is 
7.9. 

1757.  The  equivalents  of  tin,  and  of  its  compounds  with  oxygen,  chlo- 
rine, and  sulphur,  are  as  follows  : — 

Tin        -  ....  59 

Protoxide  1  atom  metal,  1  oxygen,  67 

Bioxide  1  „           2  "„  75 

Protochloride  1  „           1  chlorine,  95 

Bichloride  1  „           2  „  131 

Protosulphide  1  „           1  sulphur,  75 

Bisulphide  1  „          2  „  91 

Of  the  Compounds  of  Tin  with  Oxygen. 

1758.  The  protoxide  of  tin,  may  be  procured  by  adding  potash  to  the  protochloride. 
A  reciprocal  decomposition  takes  place  between  the  oxide  of  potassium  and  proto- 
chloride of  tin,  which  results  in  the  formation  of  the  chloride  of  potassium,  and  prot- 
oxide of  tin.    The  former  remains  in  solution,  and  the  latter  precipitates  in  the  state 
of  a  white  hydrate.     From  this  hydrate  the  water  may  be  expelled  by  heat ;  and  a 
grayish  black  anhydrous  protoxide  is  thus  obtained,  which  is  liable,  by  contact  with 
an  ignited  body,  to  take  fire,  and  consequently  to  be  converted  into  the  bioxide.  The 
hydrate  is  likewise  combustible,  though  in  a  less  degree. 

1759.  The  hydrated  bioxide  of  tin  may  be  speedily  obtained  by  the  reaction  of  tin- 
foil or  tin  powder  with  concentrated  nitric  acid,  which  is  decomposed  with  great 
violence,  bioxidizing  the  metal  without  dissolving  it.     This  oxide  may  be  obtained 
in  the  same  hydrated  state,  by  precipitation  from  the  bichloride  by  an  alkali.     The 
hydrates  thus  obtained,  though  in  composition  the  same,  are  different  in  properties. 
Both  are  soluble  in  alkalies,  but  only  the  latter  is  soluble  in  acids.     This  diversity 
continues  even  after  they  are  severally  dissolved  by  alkaline  solutions,  and  subse- 
quently precipitated  by  acids.     These  hydrated  bioxides  of  tin  are,  therefore,  con- 
ceived to  present  a  case  of  isomerism.  (1153.) 

1760.  We  may  convert  the  bioxide,  as  obtained  by  means  of  nitric  acid,  into  the 
other  modification,  by  first  changing  it  into  a  chloride,  and  then  precipitating  it  by 
potash.     According  to  Thenard,  if  the  precipitated  bioxide  be  subjected  to  heat,  it 
becomes  insoluble  in  acids. 

1761.  Jin  anhydrous  bioxide  of  tin  may  be  obtained  by  subjecting  tin  to  intense 
heat  in  contact  with  air.     It  is  white,  infusible,  and  indecomposable  by  heat.     It 
reddens  moistened  litmus  paper  when  placed  on  it.     This  oxide  is  frequently  found 
crystallized  in  nature.     It  is  employed  in  the  arts  for  the  manufacture  of  enamel, 
and,  under  the  name  of  putty,  in  grinding  glass,  and  in  making  a  paste  for  hones. 
The  bioxide  of,  tin  acts  both  as  an  oxacid  and  an  oxybase,  combining,  under  favoura- 
ble circumstances,  with  either  acids  or  alkalies. 

1762.  Concentrated  sulphuric  add,  when  cold,  has  no  action  on  tin,  but  with  the 
assistance  of  heat  dissolves  it,  disengaging  sulphurous  acid  gas,  and  forming  a  sul- 
phate of  the  protoxide  or  bioxide. 


TIN.  321 

17G3.  The  reaction  above  alluded  to,  between  concentrated  nitric  acid  and  tin, 
when  the  tin  is  in  a  state  of  minute  division,  is  followed  by  a  rise  of  temperature,  a 
decomposition  of  the  acid,  the  evolution  of  nitrogen  nearly  pure,  and  the  forma- 
tion of  the  bioxide  of  tin.  If  the  nitric  acid  be  diluted  so  as  to  have  a  specific 
gravity  of  1.114,  and  the  temperature  be  prevented  from  rising  by  cold  water,  or 
other  refrigerating  applications,  no  gas  is  disengaged  ;  since,  water  being  decom- 
posed simultaneously  with  a  portion  of  the  acid,  the  nitrogen  and  hydrogen  which 
are  thus  liberated,  unite  to  form  ammonia.  This  combines  with  part  of  the  nitric 
acid ;  so  that  at  the  close  of  the  operation  we  obtain  nitrate  of  ammonia,  mingled 
with  the  nitrate  of  the  protoxide  of  tin. 

Of  the  Compounds  of  Tin  with  the  Halogen  Class. 

1764.  A  crystalline  hydrate  of  the  Protochloride  of  tin,  may  be  obtained  by  subject- 
ing the  metal,  in  a  divided  state,  to  the  action  of  chlorohydric  acid,  and  then  crystal- 
lizing the  resulting  solution  by  evaporation.  The  protochloride  may  be  procured  in 
an  anhydrous  state,  either  by  subjecting  this  hydrate  to  a  temperature  sufficiently 
high  to  drive  off  the  water,  or  by  exposing  a  mixture  of  the  bichloride  of  mercury 
and  metallic  tin  to  a  red-heat.  When  exposed,  either  in  the  solid  state  or  in  that  of 
solution,  to  the  action  of  the  air,  or  of  liquids  containing  oxygen,  the  protochloride 
attracts  that  gas,  and  is  converted  into  an  oxychloride.  (T666.)  It  is  probable  that  in 
this  case  a  portion  of  the  protochloride  is  decomposed,  the  chlorine  forming  a  bichlo- 
ride with  the  remainder  and  the  liberated  metal  uniting  with  the  oxygen. 

1705.  The  protochloride  of  tin  acts  as  an  acid.  It  is  composed  of  one  atom  of  tin, 
and  one  of  chlorine. 

176(3.  The  bichloride  of  tin  may  be  obtained  in  the  anhydrous  state,  by  gently  heat- 
ing a  mixture  of  metallic  tin  with  the  bichloride  of  mercury.  The  bichloride  is  a 
colourless  liquid,  very  acrid  to  the  taste.  It  is  volatile,  and  when  exposed  to  the 
air  produces  dense  and  suffocating  fumes.  It  is  still  occasionally  called  by  its  ancient 
name  of  the  fuming  liquor  of  Lilamus.  By  the  addition  of  one-third  of  its  weight  of 
water,  this  bichloride  forms  a  solid  crystallizable  hydrate,  which,  nevertheless,  dis- 
solves on  the  addition  of  a  sufficient  quantity  of  water. 

1767.  I  have  been  enabled  to  form  the  bichloride  of  tin  by  the  direct  reaction  of 
the  metal  with  a  current  of  chlorine,  supplied  by  a  self-regulating  reservoir.     (798.) 
An  ingot,  of  as  much  as  three  or  four  ounces  in  weight,  was  introduced  into  a  tube  of 
about  an  inch  in  bore,  previously  drawn  into  a  capillary  perforation  at  one  end. 
(1372,  &c.)    The  smaller  portion  of  the  tube  was  curved  upwards,  nearly  so  as  to  form 
a  right  angle,  and  being  inclined  towards  the  bend,  any  liquid  generated  within 
the  tube,  had  inevitably  to  flow  into  and  occupy  the  cavity  at  the  curvature.     By 
these  means  the  operator  was  furnished  with  an  index  by  which  to  regulate  the 
supply  of  chlorine.     The  apparatus  being  thus  constructed  and  arranged,  the  tube 
had,  at  the  commencement  of  the  process,  to  be  filled  with  chlorine,  and  the  supply  of 
this  gas  afterwards  so  regulated  as  to  prevent  any  more  from  reaching  the  included 
metal,  than  it  was  competent  to  absorb.     Under  these  circumstances,  the  reaction 
proceeded  with  so  much  energy  as  actually  to  cause  the  fusion  of  the  ingot,  while  an 
ounce  measure  of  the  bichloride  was  soon  generated. 

1768.  Iodine,  bromine,  and  fluorine  severally  combine  with  tin  in  two  proportions. 
The  perfiuoride  of  tin  acts  as  a  base. 

1769.  The  cyanides  of  tin  have  never  been  isolated.     Berzelius,  however,  states, 
that  they  exist  in  combination  with  those  of  iron,  in  which  case  they  probably  play 
the  part  of  cyanobases. 

Of  the  Compounds  of  Tin  with  Sulphur  and  Selenium. 

1770.  The  protosulphidc  of  tin  is  obtained  by  heating,  in  a  crucible,  three  parts  of 
finely  divided  tin,  and  two  of  flowers  of  sulphur.     This  sulphide  is  solid,  crystalliza- 
ble, indecomposable  by  heat,  less  fusible  than  tin,  and  acts  as  a  sulphobase.     It  is 
composed  of  an  atom  of  tin,  united  to  an  atom  of  sulphur. 

1771.  The  bisulphide  of  tin  I  have  obtained  by  exposing  to  heat  in  a  coated  glass 
matrass,  a  mixture  of  two  parts  of  tin,  one  and  a  half  of  sulphur,  one  of  mercury, 
and  one  of  sal-aminoniac.*    This  compound,  generally  known  as  aurum  musivum,  or 

*  Ber/elius  suggests  that  the  mercury  probably  acts  by  bringing  the  tin  into  a 
state  of  more  intimate  mixture  with  the  sulphur;  and  the  sal-ammoniac,  by  carrying 
off,  in  consequence  of  its  volatility ,  the  heat  which  is  evolved  during  the  union  of  the 
sulphur  with  the  tin,  and  which  would  otherwise  be  sufficient  to  decompose  the 
bisulphide,  were  it  already  formed. 
41 


322  INORGANIC  CHEMISTRY. 

mosaic  gold,  is  of  a  beautiful  golden  yellow.  "When  exposed  to  a  red  heat,  it  is  de- 
composed. It  acts  feebly  as  a  sulphobase,  and  powerfully  as  a  sulphacid.  This 
sulphide,  when  spread  on  the  surface  of  the  cushions  of  electrical  machines,  has  been 
found  to  increase  their  exciting  power. 

1772.  According  to  Berzelius  there  is  a  third  sulphide,  which  contains  a  quantity 
of  sulphur,  intermediate  between  those  which  exist  in  the  protosulphide  and  the 
bisulphide. 

1773.  A  gray  selenide  of  tin  may  be  procured  by  gently  heating  finely  divided  tin 
with  selenium. 

Experimental  Illustrations. 

1774.  Exhibition  of  tin  and  of  tin  foil;  also  of  the  fum- 
ing liquor  of  Libavius,  and  the  process  for  the  generation 
of  this  chloride  in  which  an  ingot  of  tin  is  made  to  react 
with  chlorine.  Reaction  of  nitric  acid  or  nitrate  of  cop- 
per with  tin  powder.  Solution  of  tin  by  chlorohydric  acid, 
and  effects  of  the  chloride  thus,  obtained  on  some  other 
metallic  solutions.  Decoloration  of  ink  and  Prussian  blue. 
Ammonia  evolved  by  a  solution  of  tin  in  dilute  nitric  acid. 


SECTION  VIII. 

OF  BISMUTH. 

1775.  This  metal  is  found  in  nature  in  the  metallic  state;  usually,  how- 
ever, containing  a  little  cobalt  and  arsenic,  and  sometimes  sulphur.     It  is 
also  found  in  the  state  of  sulphide. 

1776.  The  only  ore  of  bismuth  which  is  explored,  is  that  in  which  it 
exists  in  the  metallic  state.     From  this  it  is  evolved  by  exposure  to  a  wood 
fire,  under  which  a  hole  is  made  to  receive  the  melted  metal. 

1777.  According  to  Berzelius,  the  bismuth  of  commerce  contains  iron 
and  arsenic,  and  perhaps  other  metals.     In  order  to  purify  it,  it  should  be 
dissolved  in  nitric  acid;  the  resulting  clear  solution  should  be  mingled  with 
water,  by  which  a  pure  hydrated  subnitrate  of  bismuth  is  precipitated. 
The  precipitate  being  dried,  is  reduced  by  the  aid  of  black  flux*  and  a 
gentle  heat. 

1778.  Properties.  —  Bismuth  is  brittle,  easily  reduced  to  powder,  and  of 
a  silvery  white  colour,  very  slightly  tinged  with  red.     It  is  pre-eminent  for 

*  The  word  flux  is  employed  to  signify  a  substance,  which,  being  added  to  a  mix-' 
ture  which  is  fusible,  or  which  contains  a  fusible  body,  promotes  the  fusion  of  the 
whole  or  a  part  of  the  aggregate.  Crude  flux  is  a  mixture  of  nitre  and  cream  of 
tartar,  or  crude  tartrate  of  potash.  White  flux  is  the  product  obtained  by  defla- 
grating the  same  mixture  in  a  crucible,  by  a  red-heat;  whereas,  when  there  is  a 
double  proportion  of  the  bitartrate,  an  excess  of  carbon,  causing  the  residue  to  be 
black,  it  receives  the  corresponding  designation.  Black  flux  is  resorted  to,  where  it 
is  an  object  to  deoxidize,  as  well  as  induce  fusion.  The  fusion  of  the  materials 
enables  them  more  readily  to  move  among  each  other,  in  obedience  to  their  respec- 
tive affinities,  and  renders  it  easier  for  metallic  globules,  as  they  are  formed,  to 
descend  to  the  bottom  of  the  vessel,  so  as  to  unite  in  one  mass. 


BISMUTH.  323 

the  facility  and  regularity  with  which  it  crystallizes.  Its  fracture  is  always 
crystalline.  Thenard  alleges  that,  when  quite  pure,  its  crystals  are  cubes, 
which  are  so  associated  as  to  form  a  four-sided  inverted  pyramid,  in  which 
the  faces  resemble  stairs.  Its  specific  gravity  is  9.82.  It  is  usually  con- 
sidered as  unmalleable ;  yet  Turner  alleges  that  it  may  be  hammered  into 
plates  while  warm.  Excepting  mercury  and  tin,  it  is  the  most  fusible  of 
the  metals  proper.  Its  fusing  point  is  476°.  It  is  oxidized  when  kept  in 
fusion  in  the  air ;  but  not  otherwise,  unless  the  air  be  moist,  in  which  case 
it  is  tarnished.  Bismuth  combines  with  phosphorus,  and  probably  in  a 
minute  proportion  with  hydrogen.  Its' equivalent  is  71. 

1779.  Bismuth  has  of  late  proved  to  be  a  most  valuable  material  for 
the  construction  of  thermo-electric  batteries.    See  my  Treatise  on  Electro- 
magnetism,  page  63. 

1780.  The  reaction  of  sulphuric  or  nitric  acid  with  bismuth,  is  very  simi- 
lar to  that  of  the  same  acids  with  tin.     Nitric  acid,  perhaps,  reacts  more 
violently  with  the  former  metal  than  with  the  latter;  since  the  addition  of  a 
small  quantity  of  concentrated  nitric  acid  to  powdered  bismuth,  causes  the 
evolution  of  so  much  heat  as  to  raise  the  temperature  of  the  mass  to  red- 
ness.    The  hydrated  subnitrate  of  bismuth,  obtained  as  abovementioned  by 
subjecting  the  nitrate  to  water,  is  of  a  fine  white  colour,  and  has  been  called 
magistery  of  bismuth.     If  chlorohydric  acid  be  present  in  the  solution,  the 
precipitate  assumes  the  form  of  minute  scales,  of  a  pearly  lustre,  called 
pearl  white.     These  precipitates  have  been  used  as  pigments  to  improve 
the  complexion,  but  are  liable  to  be  rendered  black  by  sulphydric  acid. 

Of  the  Compounds  of  Bismuth  with  Oxygen. 

1781.  There  are  two  oxides  of  bismuth;  one  is  a  protoxide,  consisting 
of  one  atom  of  metal,  and  one  of  oxygen;  the  other  a  sesquioxide,  com- 
posed, consequently,  of  two  atoms  of  metal,  and  three  of  oxygen. 

1782.  The  protoxide  may  be  obtained  by  heating  bismuth  with  access 
of  atmospheric  oxygen,  or  by  the  calcination  of  the  nitrate.    When  the  sub- 
nitrate  (magistery)  of  bismuth  is  subjected  successively  to  a  caustic  alka- 
line solution,  and  to  cold  water,  it  forms  a  white  hydrated  protoxide  of 
bismuth.     This  oxide,  when  anhydrous,  is  yellowish,  fusible  at  a  red-heat, 
devoid  of  affinity  for  atmospheric  oxygen,  and  easily  reducible  when  heated 
with  carbon  or  hydrogen.     It  acts  as  a  base. 

1783.  The  sesquioxide  of  bismuth  is  obtained  by  boiling  the  protoxide 
with  a  solution  of  the  chloride  of  potash  or  soda.*     It  is  of  a  deep  brown 
colour,  and,  at  a  temperature  a  little  below  the  boiling  point  of  mercury,  is 
decomposed.     The  sesquioxide  of  bismuth  acts  neither  as  a  base  nor  as  an 
acid. 

Of  the  Compounds  of  Bismuth  with  the  Halogen  Class. 

1784.  Either  directly  or  indirectly,  compounds  of  bismuth  may  be  produced  with 
all  the  halogen  bodies. 

17<>.  In  chlorine,  this  metal  takes  fire  spontaneously,  forming  a  protochloride, 
which,  from  the  butyraceous  consistency  assumed  in  melting,  received  from  the  old 
chemists  the  appellation  of  the  butter  of  bismuth.  This  compound  may  also  be  ob- 
tained in  the  anhydrous  state,  by  heating  three  parts  of  the  bichloride  of  mercury 
with  one  of  bismuth.  When  anhydrous,  the  protochloride  is  white,  volatile,  and 
deliquescent:  when  subjected  to  water,  a  white  insoluble  oxychloride  is  formed. 

1786.  A  crystalline  hydrate  of  the  protochloride  of  bismuth  may  be  formed  by  dis- 
solving bismuth  in  aqua  regia,  and  evaporating  the  solution. 

*  Thenard,  Traite  de  Chimie,  6eme  ed.  ii.  484. 


324  INORGANIC   CHEMISTRY. 

1787.  Bromides  of  bismuth  may  be  obtained  by  heating  bismuth  with  bromine. 
Iodides  may  be  produced  in  like  manner. 

1788.  Fluorine  and  cyanogen  both  combine  with  bismuth.    The  cyanide,  however, 
is  known  only  in  a  state  of  combination. 

Of  the  Compounds  of  Bismuth  with  Sulphur  and  Selenium. 

1789.  Bismuth  forms  a  bisulphide  when  heated  with  sulphur.     At  the  moment 
when  the  combination  takes  place,'  a  great  deal  of  heat  is  evolved.     It  is  crystalliza- 
ble,  less  fusible  than  bismuth,  and  possesses  the  metallic  lustre  and  a  grayish-yellow 
colour. 

1790.  When  selenium  is  heated  with  bismuth,  a  crystalline  selenide  is  formed  of 
a  silvery  white  colour. 

Experimental  Illustrations. 

1791.  Bismuth  and  its  oxide,  exhibited.  Its  hue  and 
habitudes  with  the  blowpipe,  compared  with  those  of  zinc, 
antimony,  and  arsenic. 


SECTION  IX. 

OF  IRON. 

1792.  This  metal  is  found  abundantly  in  nature,  principally  in  union 
with  sulphur  or  oxygen. 

1793.  Large  masses  of  iron  have  been .  observed  to  fall  to  the  earth  at 
different  times,  and  in  various  countries.     Besides  these  metallic  masses,  a 
great  number  of  stony  bodies,  called  meteorolites,  or  aerolites,  have  fallen 
in  like  manner.     In  the  latter,  iron  always  exists  both  in  the  state  of  prot- 
oxide, and  in  that  of  metallic  globules.     The  iron  in  these  globules,  and  in 
the  masses  abovementioned,  always  contains  nickel  or  cobalt,  or   both. 
Native  metallic  iron  has  also  been  found  in  small  quantities,  but  does  not 
contain  nickel  or  cobalt.     Iron  is  one  of  the  most  generally  distributed 
substances  in  the  creation,  and,  in  the  state  of  oxide,  probably  the  most 
universal  colouring  matter. 

1794.  Four  species  of  ferruginous  minerals  are  very  abundant  in  nature; 
magnetic  oxides  and  sulphides,  and  sulphides  and  oxides  which  are  not 
magnetic. 

1795.  Since  ferruginous  minerals,  if  not  magnetic  in  the  first  instance, 
becomes  so  by  exposure  to  the  flame  of  the  blowpipe,  the  magnet  is  a  most 
useful  test  for  iron.    The  ores  of  iron  consist  principally  of  the  sesquioxide, 
or  of  a  compound  of  this  oxide  with  the  protoxide,  called  the  black  or  mag- 
netic oxide.   The  means  of  extricating  iron  from  its  ores,  will  be  mentioned 
in  treating  of  the  compounds  of  iron  with  carbon,  which  will  on  that  ac- 
count be  treated  of  first. 

1796.  Properties. — The  mechanical  properties   of  iron   are   too  well 
known  to  need  description.     It  is  the  most  tenacious  substance  in  nature, 
especially  as  steel,  and  the  hardest  among  the  malleable  metals.     In  ducti- 
lity it  has  a  still  higher  pre-eminence.    Few  metals  are  more  easily  oxidized 
by  the  joint  agency  of  air  and  moisture.    In  the  pulverulent  form,  in  which 
it  is  reduced  from  the  sesquioxide  by  means  of  hydrogen,  iron  is  liable  to 
become  ignited  by  the  access  of  atmospheric  oxygen,  even  after  it  has  been 


IRON.  325 

completely  refrigerated.  This  result  is  more  likely  to  ensue,  if  a  little  alu- 
mina has  been  previously  mixed  with  the  oxide ;  since  this  prevents  the 
union  of  the  particles,  and  thus  keeps  them  in  that  state  of  minute  division 
which  is  favourable  to  the  success  of  the  experiment.  Iron  is  nearly  as 
difficult  to  fuse  as  platinum.  Its  specific  gravity  is  7.788. 

1797.  The  equivalents  of  iron,  and  of  its  compounds  with  oxygen,  chlo- 
rine, and  sulphur,  are  as  follows  : — 

Iron               -               ......  28 

Protoxide,  1  atom  metal,  1  atom  oxygen  36 
Sesquioxide, 

or          ^  2  atoms     „      3  atoms     „                           80 
Red  oxide, 
Magnetic 

or             V  3  atoms     „      4  atoms      „      v 
Black  oxide, l 

Or  1  atom  protoxide  and  1  atom  sesquioxide  } 

Protochlovide,  1  atom  metal,  1  atom  chlorine                    64 

Sesquichloride,  2  atoms    „       3  atoms     „                         164 

Protosulphide,  1  atom      ,,       1  atom  sulphur                     44 

Sesquisulphide,  2  atoms    „       3  atoms     „                          104 

Bisulphide,  1  atom      „       2  atoms     „                           60 

Of  the  Compounds  of  Iron  with  Carbon,  Boron,  Silicon,  and  Phosphorus. 

1798.  When  ferruginous  salts,  containing  carbon  as  a  constituent,  are  exposed  to 
heat  without  access  of  air,  the  iron  and  carbon  are  left  in  a  state  of  combination  in 
various  proportions.    Some  of  these  carburets,  that  from  the  oxalate,  or  from  the  tanno 
gallate  or  Prussian  blue,  for  instance,  are  liable  to  take  fire  when  exposed  to  the  air. 

1799.  The  process  of  evolving  iron  from  its  ores,  comes  under  the  fourth  case  of 
affinity,  in  which  one  body  in  excess,  combines  with  two  others  previously  united. 
The  carbon  with  which  the  ore  is  ignited,  combines  both  with  the  oxygen  and  metal, 
converting  the  one  into  a  fusible  carburet,  called  cast  iron,  the  other  into  carbonic 
acid.    The  proportion  of  carbon  in  cast  iron  varies  from  1  part  in  25,  to  1  in  15.     In 
commerce,  there  are  four  varieties  of  cast  iron;  the  ichite,  the  black,  the  gray,  and 
the  mottled.     In  the  white,  there  is  the  least  carbon,  in  the  black,  the  most;  and 
probably,  in  the  other  kinds,  less  than  in  the  black,  and  more  than  in  the  white  kind. 

1800.  It  should,  however,  be  understood,  that  cast  iron  is  probably  never  a  pure 
carburet.     Usually,  it  contains  silicon  and  manganese,  and  frequently  magnesium 
and  phosphorus.     This  last  mentioned  element  renders  the  iron  less  malleable  at  a 
high  temperature.     From  cast  iron,  the  malleable  metal  is  extricated  by  exposure  to 
heat  and  air;  by  which  carbon,  and  silicon  when  present,  are  oxidized;  the  one 
being  separated  as  a  silicate  of  iron  with  the  scoria,  the  other  escaping  as  carbonic 
acid. 

1801.  In  some  cases,  malleable  iron  is  obtained  directly  from  the  ore,  by  means  of 
heat  and  charcoal. 

1802.  Pure  malleable  iron  is  converted  into  steel,  by  being  heated  in  contact  with 
charcoal  in  ovens  without  access  of  air.    The  process  is  called  cementation.  By  these 
means,  iron  acquires  from  l-50th  to  l-120th  of  its  weight  of  carbon.     The  bars  are 
blistered  by  the  operation  as  they  are   seen  in  commerce.     Broken  up  and  welded, 
they  form  shear  steel.    Fused,  they  constitute  cast  steel. 

1803.  It  would  appear  that  silicon  is  a  frequent,  if  not  a  necessary  ingredient  in 
steel.     According  to  Berzelius,  the  presence  of  manganese  and  phosphorus  is  essen- 
tial to  the  formation  of  good  steel.     Damask  steel  is  a  peculiar  species,  which  pos. 
sesses  the  property  of  exhibiting  waving  lines  on  its  surface,  when  acted  on  by  an 
acid.     It  is  alleged  by  Thenard,  that  some  experiments  which  have  recently  been 
made,  tend  to  prove  that  this  is  owing  to  the  presence  of  two  carburets  of  iron ;  one 
of  which  is  blackened  by  the  acid,  while  the  other  resists  its  action.    I  think  it  more 
probable,  that  the  appearance  in  question  is  owing  to  a  mixture  of  iron  and  steel. 
It  has,  however,  been  ascertained  that  a  peculiar  variety  of  this  steel  called  wootz, 
which  comes  from  India,  contains  aluminium,  and  may  be  imitated  by  the  introduc- 
tion, into  steel,  of  a  minute  portion  of  that  metal. 


326  INORGANIC    CHEMISTRY. 

1804.  A  silicuret,  and  probably  a  boruret  of  iron,  maybe  obtained  by,  heating  iron 
with  a  mixture  of  charcoal  and  silicic  or  boric  acid. 

1805.  A  phosphuret  of  iron  is  produced,  when  phosphate  of  iron  is  heated  with 
lampblack.     It  resembles  iron  in  colour,  but  is  brittle,  and  fusible  by  the  blowpipe. 

Of  the  Compounds  of  Iron  with  Oxygen. 

1806.  Iron  forms  two  oxides,  a  protoxide  and  a  sesquiox- 
ide:-  the  former,  consisting  of  an  atom  of  each  constituent; 
the  latter,  of  two  atoms  of  metal,  and  three  atoms  of  oxy- 
gen.    Both  these  oxides  act  as  bases. 

1807.  The  protoxide  is  formed  during  the  solution  of 
the  metal  in  diluted  sulphuric  acid.     The  reaction  which 
ensues  under  these  circumstances,  is  always  attended  by 
the  evolution  of  hydrogen,  arising  from  the  decomposition 
of  the  water  in  combination  with  the  acid,  the  oxidation  of 
the  metal,  and  the  formation  of  a  sulphate  of  the  protoxide. 

1808.  I  infer  that  the  atom  of  water,  which,  by  a  union 
with  the  anhydrous  acid,  constitutes  the  aqueous  sulphuric 
acid  of  Berzelius,  or  in  other  words  the  acid  of  the  shops 
of  sp.  gr.  1.850,  acts  as  an  oxybase.     So  that  the  result 
may  be  ascribed  to  the  exchange  of  one  radical  for  ano- 
ther; an  atom  of  iron  taking  the  place  of  an  atom  of  hy- 
drogen.    Agreeably  to  this  view  of  the  subject,  the  aqueous 
acid  should  be  regarded  as  a  sulphate  of  hydrogen. 

1809.  The  protoxide  of  iron,  forms  with  sulphuric  acid, 
a  green  solution,  which,  by  evaporation,  yields  crystals  of 
the  same  colour,  known  in  pharmacy  as  green  vitriol,  or 
green  sulphate  of  iron.     From  a  solution  of  this  salt,  the 
protoxide  may  be  precipitated  by  an  alkaline  solution  in 
the  state  of  a  white  hydrate.     From  this  hydrate  the  water 
cannot  be  expelled  either  by  heat  or  desiccation,  without 
causing  the  protoxide  to  acquire  oxygen,  either  from  the 
water  in  union  with  it,  or  from  the  air. 

1810.  In  consequence  of  this  avidity  for  oxygen,  solu- 
tions of  this  oxide  become  gradually  more  or  less  solution3 
of  the  sesquioxide;   exchanging  their  grass  green  colour 
for  that  of  red  wine. 

1811.  The   protoxide   appears   to   exist  in   chalybeate 
springs,  and,  in  its  nascent  state,  to  be  soluble  in  water; 
although  I  do  not  find  that  other  chemists  are  aware  of 
the  fact.     Its  existence  in  them  is  ascribed  usually  to  the 
presence  of  carbonic  acid;  but  I  have  observed  it  in  the 
water  of  the  Yellow  Springs,  which  gave  no  precipitate 
with  lime-water. 


IRON.  327 

1812.  We  have  only  to  make  a  pile  of  silver  coin,  alter- 
nated with  disks  of  sheet  iron,  in  a  glass  tumbler,  supplied 
with  water,  in  order  to  impart  to  the  latter  the  property 
of  chalybeate  spring  water.     In  the  tumbler,  as  in  those 
springs,  the  red  oxide  will  soon  be  seen  precipitating,  and 
tinging,  with  its  appropriate  hue,  both  the  liquid  and  the 
vessel. 

1813.  As  light  promotes  the  further  oxidation  and  con- 
sequent precipitation  of  the  iron,  the  solution  of  the  prot- 
oxide, by  the  means  which  I  have  described,  will  be  more 
permanent  in  an  opake  vessel. 

1814.  There  does  not  appear  to  be  any  mode  in  \vhich 
the  protoxide  of  iron  can  be  isolated. 

1815.  The  sesqnioxide,  or  peroxide  of  iron,  also  called 
the  red  oxide  from  its  colour,  which  is  of  a  dingy  blood-red, 
exists  in  nature  in  great  abundance,  forming,  sometimes, 
large  beds  or  masses,  at  other  times,  botryoidal,  or  mam- 
millary  concretions. 

1816.  Ochres  consist  of  alumina,  mixed  with  the  sesqui- 
oxide  of  iron,  either  uncombined  with  water,  or  in  the  state 
of  hydrate. 

1817.  The  sesquioxide,  as  we  have  already  stated,  is 
spontaneously  produced  by  the  absorption  of  oxygen  by 
the  protoxide,  when  exposed  to  the  air.     In  fact,  by  the 
addition  of  nitric  acid  to  any  ferruginous  solution,  the  iron 
becomes  more  or  less  sesquioxidized.   On  the  other  hand,  it 
may  be  partially  deoxidized,  and  restored  to  the  state  of 
protoxide,  by  digestion  with  iron  filings,  or  by  the  addition 
of  protochloride  of  tin.     Hence,  the  black  colour  of  the 
tanno  gallate  of  iron,  which,  when  suspended  in  water, 
constitutes  common  writing  ink,  is  removed  by  the  addi- 
tion of  this  protochloride.     It  appears  probable,  that  the 
tin  passes  to  the  state  of  oxychloride  in  the  following  way. 
One  portion  of  this  metal  takes  chlorine  from  another  por- 
tion to  form  a  bichloride,  while  the  other  portion  abstracts 
oxygen  from  the  iron,  forming  of  course  an  oxide.     The 
resulting  oxide  combining  with  the  bichloride,  an  oxychlo- 
ride is  produced.     In  the  state  of  protoxide,  to  which  the 
iron  is  brought  by  the  partial  deprivation  of  oxygen,  it 
forms  a  colourless  compound  with  the  tanno  gallic  acid.* 

*  Protochloride  of  tin  is  the  most  efficient  remedy  for  removing  ink  stains,  or  iron 
mould.  It  is  made  by  the  reaction  of  chlorohydric  acid  with  an  excess  of  tin  in 
powder  or  in  tinfoil,  or  otherwise  sufficiently  comminuted.  It  is  better  to  use  it 


328  INORGANIC  CHEMISTRY. 

1818.  When  a  solution  of  the  protoxide  of  iron  is  added 
to  a  solution  of  the  chloride  of  gold,  this  metal  probably 
relinquishes  its  chlorine  to  one  portion  of  the  iron  in  the 
protoxide.     The  oxygen,  consequently  displaced,  sesqui- 
oxidizes  another  portion  of  the  iron ;   so  that  metallic  gold 
precipitates,  and  the  chloride  and  oxide  of  iron,  combining 
in  the  state  of  an  oxychloride,  remain  in  solution. 

1819.  By  intense  heat  the  acid  may  be  expelled  either 
from  a  nitrate  or  sulphate  of  iron,  and  the  sesquioxide 
consequently  obtained.     It  has  been  stated,  in  treating  of 
sulphuric  acid,  that  it  was  originally  distilled  from  copperas 
or  green  vitriol,  the  sulphate  of  the  protoxide  of  iron.    The 
oxide  which  remains  after  the  expulsion  of  the  acid,  has 
long  been  known  under  the  name  of  colcothar  of  vitriol.  The 
metal  necessarily  becomes  peroxidized  during  this  process 
by  the  partial  decomposition  of  the  acid.  (771.)     To  ren- 
render  it  free  from  all  remains  of  acid,  it  should  be  washed 
with  water. 

1820.  The  protoxide  and  sesquioxide  of  iron  combine 
in  various  proportions.     The  scales,  called  finery  cinder, 
which  fly  off  during  the  forging  of  incandescent  iron,  con- 
sist of  protoxide  and  sesquioxide.     The  oxide  formed  by 
subjecting  iron  at  a  red-heat  to  steam,  is  the  black  oxide, 
composed  of  one  atom  of  protoxide  and  one  of  sesquioxide. 

1821.  The  native  magnetic  oxide  of  the  mineralogists, 
is,  according  to  Thenard,  the  same  as  that  obtained  when 
iron  is  oxidized  by  steam. 

1822.  The  same  author  alleges  that  neither  the  hydrate 
of  the  protoxide  nor  sesquioxide  are  magnetic ;  this  quality 
being  exhibited  only  when  the  two  oxides  are  associated 
in  the  proportion  of  one  atom  of  protoxide  to  one  of  ses- 
quioxide. 

Of  the  Reaction  of  Iron  with  Acids. 

1823.  The  reaction  of  iron  with  sulphuric  acid  when  hot 
and  concentrated,  is  quite  analogous  to  that  already  de- 
scribed as  taking  place  between  that  acid,  and  mercury, 
copper,  lead,  &c.     The  reaction  of  iron  with  this  acid 

with  an  equal  portion  of  acetic  acid,  and  the  addition  of  its  volume  of  water.  The 
spot  to  be  operated  upon  should  be  first  moistened  with  water,  to  prevent  the  chlo- 
ride from  spreading  unnecessarily.  After  the  stain  disappears,  the  remains  of  the 
solution  should  be  well  washed,  as-otherwise  corrosion  might  ensue. 


IRON.  329 

when  dilute,  has  been  mentioned   and  explained  above. 
(1807.) 

1824.  In  its  habitudes  with  nitric  acid,  iron  resembles 
tin  and  bismuth.     If  the  acid  employed  be  concentrated, 
and  the  iron  minutely  divided,  the  reaction  is  liable  to  be- 
come explosive. 

1825.  With  gallic  and  tannic  acids,  as  existing  in  the 
infusion  of  galls,  the  sesquioxide  of  iron  produces  a  purple 
or  black  colour,  in  other  words,  ink.*     With  succinic  acid 
the  sesquioxide  yields  a  brown  precipitate;  with  benzoic 
acid,  an  olive  coloured  precipitate;  and  with  meconic  and 
sulphocyanhydric  acid,  a  blood-red  colour. 

Of  the  Compounds  of  Iron  with  the  Halogen  Class. 

1826.  Chlorine  forms  with   iron  a   protochloride   and 
sesquichloride,  which  correspond  in  composition  with  the 
oxides. 

1827.  The  anhydrous  protochloride  may  be  obtained  by 
passing  chlorohydric  acid  gas  over  iron  filings  heated  to 
redness  in  a  glass  tube. 

1828.  The  hydrous  protochloride  may  be  procured  by  the 
action  of  liquid  chlorohydric  acid  on  iron  filings.     The 
protochloride,  in  its  anhydrous  state,  is  of  a  pale  green 
colour,  astringent,  crystallizable,  very  soluble  in  water,  and 
volatilizable  by  heat.     When  exposed  to  the  action  of  the 
air,  it  absorbs  oxygen,  and  forms  an  oxychloride,  consist- 
ing of  the  sesquioxide,  and  sesquichloride. 

1829.  The  hydrous  sesquichloride  of  iron  is  produced, 

*  The  materials  for  common  writing  ink  are  an  infusion  of  galls,  sometimes  with 
the  addition  of  a  small  proportion  of  an  infusion  of  logwood,  and  green  sulphate  of 
iron,  which,  in  its  ordinary  state,  contains  more  or  less  of  the  sesquioxide  of  that 
metal.  The  black  hue  of  the  liquid  resulting  from  these  infusions,  increases  in  in- 
tensity by  exposure  to  the  atmospheric  oxygen,  and  consequent  increase  of  the  pro- 
portion of  sesquioxide.  Dr.  Ure  conceives  that  ink  made  of  iron,  in  an  inferior  de- 
gree of  oxidizement,  penetrates  the  paper  better  than  that  which  is  made  by  solutions 
of  the  sesquioxide,  and  finally  becomes  equally  black  upon  paper.  There  is  some 
obscurity  respecting  the  composition  of  this  liquid  on  account  of  the  discordancy  of 
opinion  which  has  existed  respecting  the  acids  of  which  it  consists. 

It  may  be  inferred  that  the  acid  prevailing  in  a  fresh  infusion  of  galls,  is  mainly 
that  which  \v;is  formerly  called  tannin,  and  latterly  tannic  acid.  This  acid  is  gradu- 
ally converted  into  gallic  acid,  when  the  infusion  in  which  it  exists  is  exposed  to 
the  air.  Either  acid  will  produce  ink,  with  ferruginous  solutions,  but  it  does  not 
appear  to  me,  that  it  is  known  which  of  the  two  answers  the  best  for  this  purpose. 
I  have  found  a  beautiful  blue  black  ink  to  result  from  the  reaction  of  a  filtered  in- 
fusion of  galls  in  cold  water  with  finery  cinder.  It  is  too  much  prone  to  precipitate, 
but  by  agitation  is  always  resuspended.  The  old  practice  of  introducing  cotton  into 
an  inkstand,  removes  this  inconvenience  in  great  measure.  Over  common  ink  it 
has  these  advantages,  it  contains  no  free  sulphuric  acid,  and  makes  no  grounds  which 
cannot  be  resuspended. 
42 


330  INORGANIC  CHEMISTRY. 

when  the  sesquioxide  of  iron  is  exposed  to  the  action  of 
chlorohydric  acid.  It  may  be  obtained  in  the  anhydrous 
state,  by  heating  iron  filings  in  an  excess  of  chlorine. 
Thus  obtained,  it  is  volatile  and  deliquescent. 

1830.  Bromine  and  iodine  form  compounds  with  iron,  which  no  doubt  correspond 
in  composition  with  its  oxides  and  chlorides. 

1831.  There  are  two  fluorides  of  iron  which  act  either  as  acids  or  bases. 

1832.  The  protocyanide  of  iron  is  formed  by  exposing  the  cyanoferrite  of  ammo- 
nium, which  is  a  compound  of  the  cyanides  of  iron  and  ammonium,  to  heat  in  a  re- 
tort.    The  cyanide  of  ammonium,  which  is  volatile,  passes  over,  leaving  the  proto- 
cyanide of  iron  in  the  form  of  a  grayish-yellow  powder.     This  cyanide  acts  as  a 
powerful  cyanacid,  combining  in  that  capacity  with  the  cyanides  of  almost  all  the 
metals.     It  also  combines  with  cyanhydric  acid,  but  whether  as  an  acid  or  a  base, 
appears  to  me  doubtful.     I  incline  to  the  opinion  that  it  acts  as  an  acid,  forming  a 
cyanoferrite  of  the  cyanobase  of  hydrogen. 

1833.  The  sesquicyanide  of  iron  is  obtained  by  mingling  a  solution  of  the  fluosili- 
cate  of  the  fluobase  of  iron  with  a  solution  of  the  cyanoferrite  of  potassium.     A  fluo- 
silicate  of  the  fluobase  of  potassium  precipitates,  and  the  sesquicyanide  of  iron  re- 
mains dissolved.    Its  solution  is  of  a  deep  brownish-yellow  colour,  and  an  astringent 
taste.     If  we  attempt  to  obtain  it  in  the  solid  form  by  desiccation,  it  is  partially 
decomposed,  and  converted  into  Prussian  blue. 

1834.  Of  Prussian  Blue. — When  the  cyanide  of  potassium  is  mingled  in  solution 
with  a  ferruginous  salt,  a  precipitate  ensues,  well  known  under  the  name  of  Prussian 
blue,  having  been  first  accidentally  discovered  at  Berlin.     It  would  seem,  that  to 
perfect  the  colour  of  this  precipitate,  both  oxides  of  iron  should  be  present;  so  that 
the  protoxide  may  produce  the  protocyanide,  and  the  sesquioxide  the  sesquicyanide. 
These  cyanides,  by  their  union,  form  the  compound  in  question.  (1299,  &c.) 

Of  the  Compounds  of  Iron  with  Sulphur  and  Selenium. 

1835.  Iron  forms  with  sulphur  a  protosulphide,  a  sesquisulphide,  and  a  bisulphide. 
Moreover,  the  protosulphide  combines  in  various  proportions  with  the  bisulphide  or 
with  the  metal. 

1836.  Hydrated  protosulphide  is  alleged  to  be  formed  during  the  combustion  which 
arises  from  triturating  with  moisture  two  parts  of  iron  filings  with  one  and  a  half  of 
sulphur.     This  hydrated  protosulphide  is  liable  to  absorb  oxygen  with  a  rapidity  so 
great  as  to  produce  ignition.     Owing  to  this  property,  its  presence  in  bituminous 
coal  beds  sometimes  causes  them  to  take  fire  spontaneously. 

1837.  Native  protosulphide  of  iron  is  of  rare  occurrence ;  but  the  magnetic  and 
bisulphides  are  abundantly  found  in  nature,  especially  the  latter,  which  is  one  of  the 
most  common  minerals.     From  its  resemblance  to  gold,  it  is  frequently  mistaken  for 
that  metal  by  inexperienced  observers.    When  intensely  heated,  a  portion  of  its  sul- 
phur sublimes;  and  hence  it  is  one  of  the  sources  of  that  important  substance. 

1838.  Of  the  I/sulphide,  it  is  alleged  by  Thenard,  that  there  are  two  varieties, 
which,  though  identical  in  composition,  are  dissimilar  in  their  crystalline  form  and 
in  their  properties.     Of  these  varieties,  only  one  is  susceptible  of  spontaneous  reac- 
tion with  air  and  moisture,  and  consequent  conversion  into  a  sulphate.    To  a  similar 
transformation  of  this  and  other  sulphides,  we  are  indebted  for  the  greater  part  of 
the  green  vitriol,  or  sulphate  of  iron,  used  in  the  arts.     Beds  of  t.besc~minerals,  in  a 
state  of  decomposition,  are  to  be  met  with  in  every  country. 

1839.  Sesfjuisiilpkide  of  iron  is  produced,  when  the  sesquioxide  of  this  metal  is 
exposed  to  a  current  of  sulphydric  acid,  provided  the  temperature  be  not  above  212°. 
At  a  higher  temperature,  a  bisulphide  results. 

1840.  The  protosulphide  and  bisulphide  of  iron,  constitute,  as  Thenard  mentions, 
the  mineral  called  magnetic  pyrites.    This  mineral  is  also  formed,  as  he  alleges,  when 
iron  in  a  state  of  intense  ignition  is  presented  to  sulphur,  and  when  either  the  ses- 
quisulphide or  bisulphide  is  fused.     In  fnct,  it  would  seem  that  he  considers  none  of 
the  other  sulphides  as  magnetic  ;  although  the  presence  of  a  greater  proportion  of 
iron  in  the  protosulphide  \voulii  lead  us  to  suspect  in  it  a  greater  susceptibility  of 
magnetic  influence.     Berzelius,  however,  considers  the  protosulphide  as  magnetic. 

1841.  The  selenide  of  iron  is  formed  by  causing  the  vapour  of  selenium  to  pass 
over  iron  filings  heated  in  a  glass  tube.    It  has  a  metallic  brilliancy,  and  a  deep  gray 
colour  approaching  to  yellow. 


ZINC.  331 

Experimental  Illustrations. 

1842.  Iron,  dissolved  by  chlorohydric  and  sulphuric 
acid.  Red  and  magnetic  oxide  of  iron,  exhibited;  and 
their  solutions  precipitated  by  galls,  and  by  cyanoferrite 
of  potassium.  Effects  of  protochloride  of  tin  on  the  colour 
of  the  precipitates.  Ores  of  iron,  rendered  magnetic  by 
the  blowpipe. 


SECTION  X. 

OF  ZINC. 

1843.  This  metal  exists  in  nature  in  four  states;  in  that  of  sulphate,  sili- 
cate, carbonate,  and  sulphide.  As  a  silicate  or  carbonate,  it  is  known  in 
mineralogy  under  the  name  of  calamine  ;  its  sulphide  is  called  blende. 

1  844.  From  calamine  or  from  blende,  when  converted  into  an  oxide  by 
roasting,  the  metal  is  obtained  by  heating  it  with  charcoal,  in  a  crucible 
with  a  hole  in  the  centre  of  the  bottom.  To  this  a  sheet  iron  tube  is  adapted 
by  which  the  zinc  is  conveyed  in  liquid  globules  or  vapour  to  a  vessel  of 
water  situated  beneath,  within  which  the  vapour  consequently  condenses. 
This  process  is  called  distillation  by  descent,  "  distillatio  per  descensum." 
Zinc  may  be  purified  by  redistillation. 

1845.  Properties.  —  -Zinc  is  of  a  brilliant  metallic  white  colour,  tinged 
with  the  hue  of  lead.     Its  structure  is  strikingly  crystalline.     Its  specific 
gravity  is  about  6.86.     Under  ordinary  circumstances  it  is  not  malleable, 
but  may  be  laminated  by  rollers  at  a  heat  somewhat  above  that  of  boiling 
water.     It  melts  at  about  680°.  That  it  may  be  volatilized  at  a  higher  tem- 
perature must  be  evident  from  the  process  by  which  it  is  obtained  as  above- 
mentioned.  (1844.)    By  exposure  to  the  atmosphere  it  is  slightly  oxidized, 
but  at  a  white  heat  burns  rapidly  with  intense  light,  the  resulting  oxide  be- 
ing volatilized  in  fumes.     Water  is  rapidly  decomposed  when  passed  in  the 
state  of  steam  over  ignited  zinc,  or  when  presented  to  it  together  with  a  due 
proportion  of  sulphuric  or  chlorohydric  acid.     Zinc  combines  with  carbon 
and  phosphorus. 

1846.  The  equivalents  of  zinc,  and  of  its  compounds  with  oxygen,  chlo- 
rine, and  sulphur,  are  as  follows  :  — 

Zinc,  .......  32 

Protoxide,  1  atom  metal,  1  oxygen,  40 

Peroxide,  doubtful. 

Chloride,  1     „        „       1  chlorine,  68 

Sulphide,  1     „        „        1  sulphur,  48 

Of  the  Compounds  of  Zinc  with  Oxygen. 

1847.  The  protoxide  of  zinc  is  formed  during  the  com- 
bustion of  the  metal  in  atmospheric  air.     From  the  light- 


332  INORGANIC  CHEMISTRY. 

ness  and  fleeciness  of  its  texture,  when  obtained  in  this 
way,  it  was  formerly  variously  called  pompholix,  nihil 
album,  or  lana  philosophica.  The  protoxide  may  be  ob- 
tained from  one  variety  of  the  ore  called  calamine,  by 
heating  it  to  expel  carbonic  acid.  To  prepare  it  as  it  is 
presented  to  us  in  the  shops,  the  ore  is  roasted,  pulverized, 
and  levigated.  A  better  process,  as  I  conceive,  is  that  of 
collecting  the  woolly  matter  produced  by  the  combustion 
of  the  metal.  But  to  either  of  these  modes  I  should  prefer 
that  of  precipitating  the  oxide  from  the  sulphate  in  solu- 
tion, by  liquid  ammonia. 

1848.  Peroxide  of  zinc  has  been  obtained  by  mingling 
bioxide  of  hydrogen  with  a  dilute  solution  of  the  nitrate  of 
this  metal,  as  in  the  process  for  the  peroxide  of  copper, 
which  it  resembles  in  many  of  its  properties.  (1706.)    The 
protoxide  usually  acts  as  a  base,  though  in  some-  cases  it 
may  act  feebly  as  an  acid.     The  peroxide  performs  the 
part  neither  of  a  base  nor  of  an  acid. 

1849.  The  reaction  of  sulphuric  acid  with  zinc  is  similar 
to  that  of  the  same  acid  with  iron.  (1807.)  When  subjected 
to  nitric  acid,  zinc  takes  all  the  oxygen  from  one  portion 
of  the  acid,  while  the  protoxide  thus  formed  is  dissolved 
by  another  portion;  meanwhile  the  nitrogen  escapes  with 
violent  effervescence.    Professor  Emmet  has  recommended 
the  reaction  of  this  metal  with  the  nitric  acid  in  nitrate  of 
ammonia,  as  the  means  of  procuring  pure  nitrogen. 

1850.  If  the  solution  of  the  acetate  of  zinc,  obtained 
by  the  reciprocal  decomposition  of  the  acetate  of  lead  and 
sulphate  of  zinc,  (522,)  be  clarified  by  subsidence  or  filtra- 
tion, and  then  evaporated,  the  acetate  of  zinc  may  be  ob- 
tained in  the  crystalline  form.     It  will  also  be  in  a  state  of 
purity  if  the  materials  have  been  used  in  the  equivalent 
proportions,  or  with  a  slight  excess  of  the  acetate  of  lead. 
Pure  acetate  of  zinc  may  also  be  obtained  by  the  process 
for  forming  the  arbor  Saturni;  as  in  that  process,  after  a 
sufficient  time,  the  lead  is  completely  precipitated  by  the 
zinc,  which  remains  in  solution.    In  this  process  a  piece  of 
zinc  being  suspended  in  a  solution  of  acetate,  or,  prefera- 
bly, nitrate  of  lead,  and  having  a  greater  affinity  for  oxy- 
gen, it  deoxidizes  the  lead.     This,  being  thus  rendered 
insoluble,  precipitates;  while  the  resulting  oxide  of  zinc  is 
seized  by  the  acid  and  dissolved. 


ZINC.  333 

1851.  The  acetate  of  zinc  is  also  obtained,  agreeably 
to  one  of  the  formulas  of  the  Pharmacopoeias,  as  a  tinc- 
ture, in  other  words,  in  alcoholic  solution,  by  subjecting  a 
mixture  of  sulphate  of  zinc  and  acetate  of  potash,  in  equi- 
valent proportions,  to  alcohol.  The  mixture  of  the  salts 
is  followed  by  a  reciprocal  decomposition,  analogous  to 
that  produced  by  the  mixture  of  sulphate  of  zinc,  and  ace- 
tate of  lead;  excepting  that  the  resulting  sulphate  of  lead 
is  quite  insoluble  in  water,  and  separates  by  precipitation; 
while,  in  the  other  case,  both  of  the  resulting  salts,  being 
more  or  less  soluble  in  water,  alcohol  is  employed  to  sepa- 
rate them.  This  liquid  does  not  dissolve  the  sulphate  of 
potash,  while  it  readily  takes  up  the  acetate  of  zinc. 

Of  the  Compounds  of  Zinc  with  the  Halogen  Class. 

1 852.  Anhydrous  chloride  of  zinc  is  formed  during  the  combustion  of 
zinc  in  chlorine.     It  was  formerly  called  the  butter  of  zinc,  from  its  con- 
sistency.    It  is  of  a  grayish-white  colour,  translucid,  astringent,  fusible  at 
the  temperature  of  boiling  water,  and  volatilizable  at  a  red-heat.     By  dis- 
solving zinc  filings  in  chlorohydric  acid,  and  evaporating  the  solution  to 
dryness,  we  may  obtain  this  chloride  in  the  state  of  hydrate. 

1853.  Zinc  combines  with  iodine,  fluorine,  and  cyanogen.     The  cyanide 
acts  as  an  acid,  the  fluoride  both  as  a  base  and  an  acid. 

Of  the  Compounds  of  Zinc  loith  Sulphur  and  Selenium. 

1854.  Sulphide  of  zinc  may  be  obtained  by  heating  the  sulphate  to  whiteness  with 
a  carbonaceous  paste.  It  is  difficult  to  combine  zinc  directly  with  sulphur;  but 
when  the  vapour  of  sulphur  is  passed  over  incandescent  zinc,  a  combination  takes 
place  with  a  violent  commotion,  and  the  evolution  of  so  much  heat  as  to  volatilize 
part  of  the  zinc.  The  same  result  ensues  when  zinc  filings  are  suddenly  and  in- 
tensely heated  with  the  persulphide  of  potassium,  or  the  powdered  bisulphide  of 
mercury. 

rw.V>.  Sulphide  of  zinc  is  solid,  yellow,  tasteless,  less  fusible  than  zinc,  indecom- 
posable by  heat  alone,  but  reducible  by  intense  ignition  with  charcoal.  It  is  a  power- 
ful sulphobase. 

I  >.">i'».  When  the  sulphate  of  zinc  is  decomposed  at  a  low  red-heat  by  hydrogen, 
an  oxysulphide,  or  in  other  words  a  compound  of  the  sulphide  and  oxide,  is  formed. 

l-'»7.  When  the  vapour  of  selenium  is  passed  over  zinc  heated  to  redness,  the 
union  of  the  two  substances  takes  place  with  violence,  being  attended  with  the  phe- 
nomena of  active  combustion.  The  resulting  selenide  is  a  yellow  powder. 

Experimental  Illustrations. 

1858.  Zinc,  subjected  to  diluted  sulphuric,  and  diluted 
chlorohydric  acid.  Arbor  Saturni,  produced  by  it  in  a  so- 
lution of  nitrate  of  lead.  Combustion  of  the  metal  in  an 
incandescent  crucible.  Its  habitudes  with  the  blowpipe, 


334  INORGANIC  CHEMISTRY. 

exhibited.     Reaction  of  zinc  filings  and  bisulphide  of  mer- 
cury; also  of  the  melted  metal  with  a  fused  nitrate. 


— »»»e  ©«<«•— 

SECTION    XL 

OF  ARSENIC. 

1859.  This  metal  is  found  in  nature,  in  combination 
with  oxygen,  sulphur,  and  various  metals.     It  is  sold  in 
commerce  under  the  name  of  cobalt,  and  in  the  state  in 
which  it  bears  this  name,  it  is  full  of  crevices,  and  so  much 
tarnished  or  blackened  by  oxidizement,  both  internally  and 
externally,  that  it  is  not  possible,  even  by  a  fresh  fracture, 
to  see  the  true  colour  and  lustre  of  the  metal. 

1860.  In  order  to  attain  this  object,  the  cobalt  (as  it  is 
absurdly  named)  should  be  coarsely  pulverized,  and  intro- 
duced into  a  glass  tube  sealed  at  one  end.     The  tube 
should  be  less  than  half  full.     Thus  prepared,  it  should  be 
placed  within  a  cylinder  of  iron,  closed  at  the  base.     The 
butt-end  of  a  gun  barrel  will  answer.     The  space  between 
the  iron  and  the   glass  should  be  filled  with  sand,  and 
another  gun  barrel  applied,  so  as  to  receive  any  fumes 
which  may  arise,  and  conduct  them  into  a  chimney.   That 
portion  of  the  glass  tube  which  contains  the  arsenic,  should 
be  kept  red-hot  for  about  half  an  hour.     After  the  appara- 
tus is  quite  cool,  the  metal  will  be  found  in  crystals  of 
great  splendour,  occupying  that  portion  of  the  glass  tube 
which  is  next  the  part  heated  to  redness. 

1861.  Properties. — Exposed  before  the  blowpipe,  arsenic 
is  distinguished  by  burning  before  it  fuses,  and  by  emitting 
copious  white   fumes,   which   have   the  odour  of  garlic. 
These  fumes  are  easily  produced,  by  projecting  a  portion 
of  the  metal  upon  a  hot  iron,  or  by  subjecting  it  in  any 
other  way  to  heat  and  air.     They  are  evolved  on  a  large 
scale  during  some  metallurgic  operations,  and,  after  being 
purified  by  a  subsequent  sublimation,  constitute  the  ar- 
senious  acid  or  white  arsenic  of  the  shops.     This  metal  is 
extremely  brittle  and  friable,  and,  when  newly  sublimed, 
has  the  colour  and  brilliancy  of  polished  steel.    It  requires 
less  heat  to  vaporize  than  to  fuse  it;  so  that  it  cannot  be 
melted  without  the  aid  of  a  pressure  greater  than  that  of 


ARSENIC.  335 

the  atmosphere.  Thenard  alleges  that  it  may  be  sublimed 
in  a  retort  filled  with  nitrogen,  at  the  temperature  of  356°. 
I  am  under  the  impression,  that  the  nitrogen  must  co- 
operate as  a  solvent  in  this  result ;  taking  up  the  metal  in 
the  warmer  part  of  the  retort,  and  depositing  it  in  the 
colder  part.  1  have  ascertained  that  metallic  arsenic, 
situated  in  a  glass  tube  immersed  in  melted  lead,  is  not 
volatilized,  unless  so  far  as  it  may  be  oxidized  ;  and,  more- 
over, in  the  process  for  obtaining  the  arsenical  ring,  I  have 
remarked  that  it  is  formed  just  beyond  the  part  of  the  tube 
which  is  reddened  by  the  heat. 

1862.  The   following  table   gives   the   equivalents   of 
arsenic,  and  of  its  compounds  with  oxygen,  chlorine,  and 
sulphur. 

Arsenic,  38 
Suboxide,  doubtful. 

Arsenious  acid,  2  atoms  metal,  3  atoms  oxygen,  100 

Arsenic  acid,  2  atoms  „  5  atoms        „  116 

Protochloride,  1  atom  „  1  atom  chlorine,  74 

Sesquichloride,  2  atoms  „  3  atoms        „  184 

Protosulphide,  1  atom  „  1  atom  sulphur,  54 

Sesquisulphide,  2  atoms  „  3  atoms       „  124 

Persulphide,  2  atoms  „  5  atoms       „  156 

Of  the  Compounds  of  Arsenic  with  Oxygen. 

1863.  According  to  Berzelius,  the  black  matter  which 
obscures  the  brilliancy  of  metallic  arsenic  on  exposure  to 
the  air,  is  a  suboxide.     Thenard  seems  inclined  to  con- 
sider it  as  a  protoxide;  while  by  other  chemists  it  is  treat- 
ed as  a  mixture  of  arsenious  acid  and  the  metal ;  as,  when 
exposed  to  heat  or  to  acids,  it  yields  arsenious  acid,  and 
metallic  arsenic.     But  as  it  appears  that  arsenious  acid  is 
a  compound  of  oxygen  and  the  metal,  in  the  ratio  of  three 
atoms  of  the  former  to  two  of  the  latter,  it  would  be  rea- 
sonable to  infer  the  existence  of  a  compound  consisting  of 
an  atom  of  each.     Besides,  it  has  been  ascertained  by 
Berzelius,  that  the  exposure  of  arsenic  to  air  never  causes 
an  absorption  of  more  than  eight  per  cent,  of  oxygen; 
whereas,  to  form  arsenious  acid,  the  metal  must  absorb 
thirty-two  per  cent.     Now  it  seems  very  improbable  that, 
under  the  same  circumstances,  one  portion  of  the  metal 


336  INORGANIC  CHEMISTRY. 

should  absorb  thirty-two  per  cent,  of  oxygen,  while  ano- 
ther portion  should  absorb  none. 

1864.  Arsenious  acid  is  found  in  nature  both  in  crystal- 
line form  and  in  that  of  white  powder.     It  forms  the  fumes 
which  are  so  copiously  evolved  when  arsenic  is  ignited  in 
the  air.     It  is  milk-white,  has  a  rough  and  slightly  acid 
taste,  followed  by  a  flavour  feebly  sweet.     It  is  hardly 
necessary  to  state  that  it  is  a  virulent  poison.     When 
subjected  in  open  vessels  to  a  low  red-heat,  it  softens,  and 
sublimes,  in  the  form  of  a  white  powder,  or,  when  the  ves- 
sels are  large  and  the  operation  slow,  in  regular  octohe- 
dral  crystals. 

1865.  Arsenious  acid  is  soluble  in  water,  but  not  to  any 
great  extent.     Berzelius  states  that  a  saturated  solution  of 
it  in  boiling  water,  in  which  the  deposition  of  crystals  has 
commenced,  contains   but  a  twelfth  or  thirteenth  of  its 
weight.     There  is  much  uncertainty,  and  some  mystery, 
respecting  the  extent  of  its  solubility  in  cold  water.     Ber- 
zelius quotes  an  observation  made  by  Fischer,  that  the 
portion  employed  is  never  entirely  dissolved;  and  that  as 
the  ratio  of  the  water  to  the  acid  increases,  this  being  al- 
ways in  excess,  the  quantity  dissolved  lessens.     Thus  80 
parts  of  the  former  take  up-^Vth  of  its  weight;  160  parts, 
-rioth;  240  parts,  ^th;  and  1000  parts,  only  ^Voth. 

1866.  Arsenious  acid,  when  subjected  in  close  vessels  to 
a  heat  approaching  to  redness,  fuses  into  a  transparent 
glass  of  the  specific  gravity  of  3.699,  unchangeable  in  dry 
air,  but  gradually  becoming  white  and  opake  in  a  humid 
atmosphere.     In  the  last  mentioned  state,  it  appears  to  be 
more  soluble  in  boiling  water,  and  to  be  retained  in  solu- 
tion to  a  greater  extent  than  in  the  transparent  state. 
The  transparent  acid  reddens  litmus ;  while,  by  the  opake, 
litmus  previously  reddened  may  be  restored  to  its  original 
colour.     These  varieties  of  arsenious  acid  are,  therefore, 
considered  as  isomeric.  (1153.) 

1867.  Of  Arsenic  acid. — By  digestion  in  aqua  regia  or  in 
strong  nitric  acid,  evaporation  of  the  resulting  solution  to 
dryness,  and  subsequent  ignition  nearly  to  redness  in  a 
platinum  crucible,  arsenious  acid  acquires  two  additional 
atoms  of  oxygen ;  so  that  a  compound  is  formed  in  which 
the  metal  is  to  the  oxygen,  in  the  proportion  of  two  atoms 
to  five.     This  compound  is  arsenic  acid,  which   is  solid, 
white,    and   caustic,    and   capable   of   reddening   litmus. 


ARSENIC.  337 

When  exposed  to  heat  it  melts  into  a  glass ;  but  if  the 
heat  be  pushed  to  redness,  it  is  decomposed  into  arsenious 
acid  and  oxygen  gas.  This  is  a  more  powerful  acid,  a 
more  virulent  poison,  and  more  energetic  in  its  affinities, 
than  arsenious  acid.  Like  other  acids,  which  bear  a  high 
temperature  without  decomposition  or  volatilization,  it 
expels,  when  aided  by  heat,  the  volatile  acids  from  their 
combinations.  It  forms,  with  certain  metallic  oxides,  salts 
which  crystallize  in  the  same  form  as  the  corresponding 
phosphates;  whence,  as  I  have  elsewhere  stated,  (474,) 
arsenic  and  phosphoric  acid  are  said  to  be  isomorphous. 
Of  such  bodies,  one  may  be  substituted  for  the  other  in 
crystalline  compounds,  without  altering  the  form  of  the 
resulting  crystals. 

1868.  Arsenic  acid  is  deliquescent,  and  much  more  so- 
luble than  arsenious  acid ;  yet  after  being  vitrified  by  heat, 
it  does  not  dissolve  completely  at  first,  but  deposites  a 
white  powder,  which,  by  frequent  stirring,  finally  dissolves. 
In  consequence  of  this  and  some  other  differences  in  their 
properties,  it  has  been  supposed  that  the  melted  and  un- 
melted  arsenic  acids  are  isomeric  with  regard  to  each 
other. 

1869.  Arsenious   and   arsenic  acid  severally  combine 
with  the  metallic  oxides.     Arseniate  of  potash  is  formed, 
when  arsenious  acid  or  metallic  arsenic  is  deflagrated  with 
nitrate  of  potash.     Fowler's  solution,  the  liquor  potasses,  ar- 
senitis  of  the  U.  S.  Pharmacopoeia,  is  made  by  boiling  ar- 
senious acid  and  carbonate  of  potash,  of  each  64  grains, 
with  a  pint  of  distilled  water,  and  adding  four  fluidrachms 
of  the  spirit  of  lavender.     The  arsenious  acid,  displacing 
the  carbonic  acid,  forms  with  the  alkali  an  arsenite  of  pot- 
ash.    This  solution  produces  a  yellow  precipitate  with  ni- 
trate of  silver,  without  the  aid  of  ammonia,  as  the  place  of 
this  base  is  supplied  by  the  potash. 

1870.  The  soluble  arsenites  and  arseniates  yield  preci- 
pitates with  solutions  of  copper  and  silver,  and  destroy  the 
blue  colour  of  the  iodide  of  starch,  by  the  superior  affinity 
of  iodine  for  arsenic.     In  the  instance  of  copper  and  sil- 
ver, an  arsenite  or  arseniate  of  those  metals  is  formed. 
The  arsenite  of  copper  is  of  an  apple-green  colour,  and  forms 
a  pigment  called  Scheele's  green.     The  arsenite  of  silver  is 
yellow  ;  the  arseniate,  brick-red. 

1871.  Sulphuric  acid  when  cold  does  not  react  with  ar- 

43 


338  INORGANIC  CHEMISTRY. 

senic;  but  when  warm,  the  acid  is  decomposed,  and  arse- 
nious  acid  formed. 

1872.  Of  nitric  acid  the  reaction  with  arsenic  is  similar 
to  the  reaction  of  sulphuric  acid  with  the  same  metal ;  ex- 
cept that  it  takes  place  without  the  aid  of  heat,  and  that 
the  arsenious  acid  which  is  at  first  produced,  is  finally  con- 
verted into  arsenic  acid. 

i 

Of  the  Compounds  of  Arsenic  with  the  Halogen  Class. 

1873.  A  sesquichloride  of  arsenic  is  obtained  by  the  direct  reaction  of 
chlorine  with  arsenic,  or  by  the  distillation  of  this  metal  with  the  .bichloride 
of  mercury.     If,  in  this  process,  the  protochloride  of  mercury  be  substituted 
for  the  other,  a  protochloride  of  arsenic  is  generated :  and  by  the  reaction 
of  the  metal  with  an  excess  of  chlorine,  a  perchloride  results. 

1874.  The  sesquichloride  is  a  colourless,  fuming  liquid,  of  an  oleaginous 
consistency,  quite  analogous,  both  as  to  the  means  of  evolution  and  its  pro- 
perties, to  the  bichloride  of  tin,  or  fuming  liquor  of  Libavius.  (1766.) 

1875.  Bromine  and  iodine  severally  form  compounds  with  arsenic,  which 
correspond  in  composition  with  the  sesquichloride. 

1876.  The  fluoride  of  arsenic  is  a  colourless,  fuming  liquid,  which  pro- 
bably consists  of  two  atoms  of  arsenic,  and  three  of  fluorine. 

Of  the  Compounds  of  Arsenic  with  Sulphur  and  Selenium. 

1877.  There  is  scarcely  any  limit  to  the  number  of  proportions  in  which 
arsenic  and  sulphur  appear  to  be  capable  of  combining;  yet  Berzelius  ad- 
mits the  existence  of  but  five  distinct  sulphides,  and  Thenard  recognises 
only  three, — a  protosulphide,  a  sesquisulphide,  and  a  persulphide.     By  the 
union  of  these  with  various  quantities  of  the  metal,  or  of  sulphur,  all  the 
other  compounds  are  supposed  to  be  produced. 

1878.  The  proto,  sesqui,  and  persulphide  severally  combine  with  sulpho- 
bases,  as  sulphacids. 

1879.  The  protosulphide  of  arsenic^  known  in  commerce  by  the  name 
of  realgar •,  may  be  obtained  by  heating  a  mixture  of  two  parts  of  sulphur, 
and  rather  less  than  three  and  a  half  parts  of  arsenic.     It  is  procured  in 
the  large  way  by  distilling  arsenious  acid  with  sulphur.     It  is  tasteless, 
crystallizable,  less   fusible   than    arsenic,  and   of   an   orange-red   colour. 
When  heated  in  close  vessels  it  volatilizes  unchanged,  but  if  the  air  be  ad- 
mitted it  is  converted  into  arsenious  and  sulphurous  acid.    It  is  found  native. 

1880.  The  sesquisulphide  is  obtained  by  adding  chlorohydric  acid  to  a 
mixed  solution  of  sulphide  of  potassium  and  arsenite  of  potash.     The  oxy- 
gen of  the  arsenious  acid  and  of  the  potash  unites  with  the  hydrogen  of  the 
chlorohydric  acid,  the  chlorine  with  the  potassium,  and  the  sulphur  with  the 
arsenic.     The  chloride  of  potassium  remains  in  solution,  while  the  arsenic 
and  sulphur  precipitate  in  the  state  of  sesquisulphide,  and  in  the  form  of 
beautiful  yellow  flocks. 

1881.  The  sesquisulphide  is  found  in  nature,  and  is  known  in  commerce 
under  the  name  of  orpiment.     It  is  crystallizable.     When  heated  gently  in 
close  vessels  it  melts,  and  if  the  heat  be  further  elevated,  volatilizes,  and 
may  be  condensed  unchanged.     If  the  access  of  air  be  permitted  during 
the  operation,  sulphurous  and  arsenious  acid  are  formed. 

1882.  The  persulphide  of  arsenic  is  formed  by  passing  sulphydric  acid 


ARSENIC.  339 

gas  through  a  solution  of  arsenic  acid  in  water.     It  is  yellow,  and  resem- 
bles orpiment.     It  is  fusible,  volatilizable,  and  capable  of  reddening  litmus. 

1883.  A  selenide  is  produced,  when  arsenic  is  dropped  into  selenium, 
previously  liquefied  by  heat.     If  this  selenide  be  subjected  to  distillation  at 
a  red-heat,  a  perselenide  is  obtained. 

Of  the  Compounds  of  Arsenic  with  Phosphorus  and  Hydrogen. 

1884.  A  phosphuret  of  arsenic  may  be  formed  by  heating  phosphorus 
with  the  metal.     It  is  black  and  brilliant. 

1885.  Of  arseniuretted  hydrogen. — If  in  charging  the  self- regulating 
reservoir  for  the  evolution  of  hydrogen,  (797,  &c.)  an  aqueous  solution  of 
arsenious  acid  be  substituted  for  water,  the  other  materials  being  as  usual 
sulphuric  acid  and  zinc,  arseniuretted  hydrogen  will  be  evolved  with  no  less 
facility,  than  that  with  which  the  evolution  of  the  pure  gas  is  accomplished, 
when  the  arsenious  acid  is  not  present. 

1886.  When  this  gas  is  made  to  pass  through  a  tube  kept  by  means  of 
a  lamp  or  a  coal  fire,  as  hot  as  the  glass  will  bear,  the  arsenic  is  precipi- 
tated in  the  metallic  form,  in  the  cooler  part  of  the  tube,  just  beyond  the 
heated  part. 

1887.  The  process  above  described,  is  decidedly  preferable  to  any  other, 
not  only  as  respects  convenience  and  economy,  but  the  safety  of  the  ope- 
rator. 

1888.  To  procure  this  gas  devoid  of  pure  hydrogen,  Soubieran  recom- 
mends that  an  alloy  of  equal  weights  of  arsenic  with  zinc  be  made  by 
fusion,  and  subjected  to  strong  chlorohydric  acid. 

1889.  If  confidence  is  to  be  placed  in  the  recommendation  of  the  distin- 
guished chemist  above  named,  it  follows,  that  by  the  introduction  of  such 
an  alloy  into  the  self-regulating  reservoir,  substituting  strong  chlorohydric 
for  diluted  sulphuric  acid,  there  would  be  a  supply  of  pure  arseniuretted 
hydrogen  at  command. 

1890.  Arseniuretted  hydrogen  is  highly  inflammable,  in  common  with 
all  other  aeriform  compounds  of  hydrogen.     It  is  extremely  deleterious  to 
life,  being  injurious  when  liberated  in  quantities  too  small  to  be  immediately 
annoying  to  the  operator.     It  is  productive  of  nausea  and  vomiting,  some- 
times of  constipation,  sometimes  of  purging.     As  palliatives  of  these  symp- 
toms, Berzelius  recommends  warm  tea,  and  sulphydric  acid  gas. 

1891.  In  generating  this  gas  for  illustration,  by  the  apparatus  employed 
for  the  philosophical  candle,  (805,)  I  inadvertently  inhaled  enough  to  pro- 
duce a  transient  indisposition.     Gehlen,  a  respectable  German  chemist, 
lost  his  life  by  a  similar  inadvertency.     This  gas  is  the  more  insidious, 
since  we  are  not  warned  of  its  presence  by  the  fetidity  of  its  odour,  as  in 
the  case  of  the  combinations  of  hydrogen  with  sulphur  and  phosphorus,  and 
other  substances.     A  ten-thousandth  part  of  this  gas  may  be  detected  in  a 
gaseous  mixture,  by  the  metallic  pellicle  which  it  causes  upon  a  solution  of 
corrosive  sublimate. 

1892.  Oil  of  turpentine  appears  to  form  a  crystalline  compound,  by  re- 
acting with  arseniuretted  hydrogen. 

1893.  A  solid  compound  of  arsenic  with  hydrogen  has  been  made,  by 
subjecting  an  alloy  of  potassium  and  arsenic  to  water ;  and  likewise  by  the 
decomposition  of  water  by  the  Voltaic  series,  one  of  the  wires,  employed  for 
the  purpose,  terminating  in  a  piece  of  arsenic  immersed  in  that  liquid. 


340  INORGANIC  CHEMISTRY. 

Experimental  Illustrations. 

1894.  Appearance  and  habitudes  of  arsenic,  in  its  me- 
tallic and  crystalline  form,  contrasted  with  those  of  zinc, 
antimony,  and  bismuth.      Arsenious  acid  and  its  solutions, 
exhibited;  also,  Fowler's  solution,  or  solution  of  arsenite 
of  potash.     Arsenious  and  arsenic  acid,  in  solution,  added 
to  large  vessels  of  clear  water,  and  detected  by  sulphy- 
dric  acid,  or  by  ammoniacal  nitrate  of  silver  or  copper. 
Same   acids   precipitated  by   lime-water.     Exhibition   of 
Scheele's  green,  or  arsenite  of  copper.     Combustion  of 
arseniuretted  hydrogen,  displayed. 

Of  the  Means  of  detecting  Arsenic,  in  Cases  where  poisoning 
by  Arsenical  Compounds  is  suspected. 

1895.  As  respects  arsenic,  the  most  important  object  of 
attention  is  the  means  of  detecting  this  metal,  in  cases  in 
which  an  arsenical  compound  may  be  used  as  a  poison. 

1896.  The  first  steps  are  of  course  directed  to  the  col- 
lection and  preservation  of  all  the  matter  which  may  have 
come  from  the  patient  in  vomiting,  or  which  may  be  ob- 
tained by  opening  the  stomach.     As  the  combination  of 
this  metallic  poison  usually  administered  is  arsenious  acid 
in  the  pulverulent  form,  all  the  matter  collected  and  the 
surface  of  the  stomach  should  be  rigidly  examined,  in  order 
to  detect  any  particles  which  may  remain  in  that  state. 
Berzelius  counsels  us  especially  to  scrutinize  those  spots  in 
the  stomach  which  appear  to  have  been  inflamed,  in  order 
to  ascertain  whether  any  particles  of  the  poison  are  lodged 
in  them. 

1897.  In  the  next  place,  the  whole  mass,  collected  and 
preserved  as  above  advised,  should  be  thrown  into  water, 
which,  while  stirred  to  cause  the  suspension  in  it  of  the 
lighter  portions  of  the  matter,  should  be  poured  off,  to- 
gether with  that  lighter  matter  from  the  heavier  subsiding 
portion.    The  liquid  thus  separated  should  be  filtered;  and 
both  the  resulting  filtered  solution,  and  the  heavier  matter 
which  may  have  sunk  to  the  bottom  of  the  vessel,  should 
be  evaporated  to  dry  ness  in  an  appropriate  oven,  or  in  a 
vessel  kept  hot  by  boiling  water.     The  whole  being  quite 


ARSENIC.  341 

dry,  it  should  be  introduced  into  a  glass  or  porcelain  ves- 
sel ;  and,  adding  a  sufficient  quantity  of  strong  nitric  acid 
to  cover  the  mass,  it  should  be  subjected  to  a  heat  adequate 
to  cause  a  brisk  reaction.  This  should,  if  necessary,  be 
sustained  by  further  additions  of  the  acid,  until  there  is  no 
longer  any  organic  matter  undecomposed. 

1898.  As  nitric  acid  can  have  no  other  effect  upon  ar- 
senic than  that  of  converting  it  into  arsenic  acid,  in  which 
state  it  is  less  volatile  than  in  any  other;  this  process  tends 
at  the  same  time  to  annihilate  the  organic  impurities,  and 
to  secure  the  metal.     Thus  the  matter  to  be  assayed  is 
much  diminished  in  bulk,  and  if  it  contain  arsenic  must 
hold  it  as  arsenic  acid,  which  is  more  soluble  than  arseni- 
ous  acid.     Hence,  if  the  dry  mass  be  digested  with  water, 
a  solution  will  be  obtained,  which,  being  filtered,  may  be 
precipitated  by  lime-water.     The  arseniate  of  lime  which 
precipitates,  being  dried,  should  be  mingled  with  about 
one-fourth  of  its  weight  of  powdered  charcoal,  and  intro- 
duced into  a 'glass  tube,  sealed  at  one  end.     The  mixture 
having  been  made  to  settle  down  to  the  sealed  end  within 
as  narrow  limits  as  possible,  a  little  cotton  wick  must  be 
fastened  to  the  end  of  a  wire,  by  twisting  the  wire  so  as  to 
form  one  end  into  an  eye,  and  passing  the  wick  through 
the  eye,  and  winding  it  about  the  end  of  the  wire,  until  a 
plug  of  cotton  be  made  just  large  enough  to  slide  in  the 
tube  like  a  piston.     For  greater  security,  the  wick  may  be 
wound  about  the  wire,  so  that  one  end  may  be  held  in  the 
hand.     By  means  of  the  piston,  thus  formed,  the  portion 
of  the  tube,  not  occupied  by  the  mixture,  may  be  wiped 
clean.     The  tube  should  now  be  subjected  to  the  flame  of 
a  spirit  lamp,  the  piston  being  retained  in  it,  as  near  the 
mixture  as  it  can  be  without  being  injured  by  the  heat. 
The  heat  should  be  applied  at  first  to  the  anterior  part  of 
the  mass,  proceeding  to  the  posterior  part  afterwards ;  and 
as  soon  as  the  whole  ceases  to  give  out  aqueous  vapour, 
the  piston  should  be  passed  quickly  down,  so  as  to  wipe 
away  the  moisture  condensed,  together  with  any  accom- 
panying  foulness.     The  piston  being  again  beyond  the 
reach  of  the  heat,  the  part  of  the  tube  containing  the  mix- 
ture should,  by  the  aid  of  a  blowpipe,  be  exposed  to  a  tem- 
perature as  high  as  the  glass  will  bear.  If  there  be  arsenic 
in  the  mixture,  it  will  now  appear  in  a  bright  metallic  ring, 
just  beyond  that  part  of  the  tube  which  was  heated  red- 


342  INORGANIC  CHEMISTRY. 

hot.  On  cutting  the  tube  at  the  part  where  the  ring  ap- 
pears, and  heating  it  by  a  spirit  lamp,  the  alliaceous  smell 
of  arsenic  will  be  perceived,  if  this  metal  be  present;  and 
the  same  smell  will  be  experienced  on  igniting  the  cotton  of 
the  piston  above  mentioned. 

1899.  The  process  thus  described  for  obtaining  the  ar- 
senical ring  is  nearly  the  same  as  that  which  I  employed 
in  the  analysis  of  some  matter  sent  to  me  from  Westches- 
ter  by  Dr.  Thomas;  having  been  obtained  from  the  sto- 
mach of  a  woman  poisoned  by  her  husband.     I  afterwards 
repeated  it  successfully  at  Westchester,  in  presence  of 
Dr.  Thomas  and  another  physician ;  and  upon  their  evi- 
dence of  the  result  so  obtained,  the  murderer  was  con- 
victed.    Before  his  execution  he  confessed  himself  to  be 
guilty. 

1900.  Where  no  arsenic  can  be  detected  in  the  contents 
of  the  stomach,  it  may  be  found  in  the  membranes,  or 
coats.     Hence,  in  making  the  examination  for  arsenic,  the 
stomach  should  be  boiled  in  nitric  acid,  until  all  the  organic 
matter  is  destroyed. 

1901.  Very  minute  quantities  of  arsenic  may  be  detected 
by  the  aid  of  silver  or  copper  in  solution.     With  silver, 
arsenic  acid  gives  a  brick-red,  arsenious  acid,  a  yellow 
precipitate.     With  copper,  arsenious  acid  produces  a  very 
striking   green  precipitate   of  arsenite  of  copper,  called 
Scheele's    green.     Sulphydric    acid   gas    produces,    with 
either  acid,  a  yellow  precipitate  of  sulphide  of  arsenic. 
As  these  results  are  precarious,  and  liable  to  be  produced 
by  other  causes,  they  should  not  be  considered  as  conclu- 
sive evidence. 

1902.  In  the  case  of  the  murder  above  mentioned,  I 
found  that  the  arsenic  acid,  as  procured  from  the  contents 
of  the  stomach,  would  not  assume  the  appropriate  hue  in 
precipitating  with  silver,  whether  before  or  after  its  union 
with  lime.     Instead  of  a  brick-red,  it  was  of  a  muddy 
colour.     By  Dr.  Feutchwanger,  who  was  present  during 
many  of  my  experiments,  this  was  ascribed,  correctly,  as 
I  believe,  to  phosphoric  acid.   It  has  been  stated,  that  it  is 
difficult  to  separate  these  acids  when  associated,  from  their 
isomorphism,  or,  in  other  words,  crystallizing  in  the  same 
form.  (474.) 

1903.  By  simple  affinity,  neither  arsenious  nor  arsenic 
acid  can  be  precipitated  by  the  soluble  salts  of  silver  or 


ARSENIC.  343 

copper.  Hence  an  alkali  must  be  present,  either  in  union 
with  the  arsenical  acids,  or  with  the  metallic  salt.  This 
object  is  attained  conveniently,  by  the  addition  of  ammonia 
to  the  nitrate  of  silver  or  copper;  as,  with  either  of  those 
metals,  that  alkali  forms  a  soluble  ammoniacal  nitrate. 
(524). 

1904.  A  great  improvement  in  our  means  of  detecting 
arsenic  has  been  introduced  by  Marsh,  of  London.     It  has 
been  mentioned,  (1885,)  that  if  in  the  process  for  evolving 
hydrogen  by  a  self-regulating  reservoir,  an  aqueous  solu- 
tion of  arsenious  acid  be  substituted  for  pure  water,  the 
materials  and  manipulation  being  otherwise  the  same,  in 
lieu  of  pure  hydrogen,  arseniuretted  hydrogen  will  be  ge- 
nerated.    From  the  observations  of  the  ingenious  mecha- 
nician above  named,  it  appears,  that  if  any  mixture  con- 
taining arsenic  be  added  to  water  and  acid,  used  in  an 
analogous  miniature  apparatus,  the  nascent  hydrogen  will 
combine  with  the  arsenic,  however  minute  the  proportion. 
Consequently,  a  jet  of  the  gas  when  inflamed,  by  its  hue, 
fume,  and  odour,  and  still  more  when  allowed  to  play  upon 
the  surface  of  a  piece  of  porcelain  or  glass,  will  demon- 
strate the  presence  of  arsenic.     In  this  last  mentioned  case, 
a  dark  stain  will  be  made,  consisting  of  concentric  circles, 
of  which  that  which  is  central  will  have  the  metallic  hue  of 
the  arsenical  ring,  especially  when  examined  through  the 
glass. 

1905.  The  great  objection  to  this  process,  as  it  came 
from  the  hands  of  Marsh  is,  that  when  the  proportion  of 
arsenic  is  very  small,  the  whole  may  escape  before  the 
operator  may  be  enabled  to  detect  it.     Hence,  it  wrould 
seem  preferable  to  resort  to  the  expedient  recommended 
by  .Soubieran,  of  passing  it  through  a  tube  heated  by  a 
lamp  (1886);  or  to  pass  all  the  gas  generated  through 
some  liquid  competent  to  effect  a  complete  absorption  of 
the  arsenic.     For  this  purpose  a  solution  of  corrosive  sub- 
limate might  answer.  (1891.) 

Experimental  Illustrations. 

1906.  Small  portions  of  arsenious  acid,  or  of  the  ar- 
seniate  of  lime,  mingled  with  powdered  charcoal,  and  sub- 
jected to  heat  in  a  glass  tube.     Arsenical  ring,  produced 
and  exhibited. 


344  INORGANIC  CHEMISTRY. 

1907.  Self-regulating  reservoir  of  hydrogen,  charged 
with  an  aqueous  solution  of  arsenious  acid,  sulphuric  acid, 
and  zinc.  (796,  &c.)  Deposition  produced  by  the  flame 
upon  glass,  mica,  or  porcelain.  Gas  passed  through  a 
glass  tube,  reddened  by  a  lamp,  or  gas  flame,  deposits  me- 
tallic arsenic  in  a  film  resembling  in  appearance  the  ar- 
senical ring. 


SECTION  XII. 

OF    ANTIMONY. 

1908.  Antimony  sometimes  occurs  in  nature  in  the  metallic  state  and  in 
that  of  oxide,  also  abundantly  as  a  sulphide.     It  is  in  fact  to  the  sulphide 
that  the  name  of  antimony  is  given  in  commerce,  the  metal  being  designated 
as  the  regulus  of  antimony. 

1909.  The  ores  of  this  metal  had  been  known  for  a  long  time;  but  for 
its  extraction  from  them,  the  world  is  indebted  to  Basil  Valentine,  who 
lived  towards  the  close  of  the  fifteenth  century.     Since  that  period,  from 
its  utility  in  medicine,  it  has  been  eminently  an  object  of  investigation. 

1910.  Metallic  antimony  may  be  obtained  by  mingling  the  sulphide  with 
two-thirds  of  its  weight  of  bitartrate  of  potash,  and  one-third  of  its  weight 
of  nitre,  and  deflagrating  the  mixture  in  a  red-hot  crucible.     The  oxygen 
of  the  nitre  converts  the  sulphur  into  sulphurous  acid,  which  escapes  ;  while 
the  alkali  of  both  the  salts  operates  as  a  flux,  or  in  other  words  promotes 
the  fusion  of  the  mass.     The  carbon  of  the  tartaric  acid  counteracts  the 
oxidizement  of  the  metal. 

1911.  Charcoal,  intimately  intermingled  with  carbonate  of  potash  or 
soda,  may  be  used  instead  of  the  bitartrate. 

1912.  Antimony  thus  obtained  is  not  quite  pure.     To  render  it  so  it  may 
be  dissolved  in  aqua  regia,  precipitated  in  the  state  of  oxychloride  by  water, 
and  revived  by  ignition  with  bitartrate  of  potash. 

1913.  Properties.—  Antimony  is  so  brittle  as  to  be  easily  pulverized. 
It  displays  a  crystalline  structure,  and  may  be  crystallized  by  the  process 
resorted  to  in  the  case  of  sulphur.  (750.)     When  quite  pure  and  newly 
fractured,  it  is  of  a  silver-white  colour,  and  very  brilliant.     If  it  be  rubbed 
between  the  fingers,  they  acquire  a  perceptible  odour.     Its  specific  gravity 
is  6.7.     It  fuses  a  little  below  a  red-heat.     When  thrown  in  a  state  of 
fusion  upon  a  board,  it  produces  a  beautiful  effect,  being  dispersed  into  a 
multitude  of  ignited  globules,  which  emit  copious  fumes  of  oxide,  and  leave 
their  traces  upon  the  board.     The  temperature  of  the  globules  seems  to  be 
supported  by  their  own  combustion. 

1914.  A  single  globule  of  the  metal,  being  brought  to  a  state  of  ignition 
by  the  blowpipe  flame  upon  a  piece  of  charcoal,  if  held,  after  operation  of 
the  blowpipe  is  discontinued,  in  a  current  of  air,  such  as  exists  usually  at 
an  aperture  in  a  flue,  will,  in  consequence  of  the  heat  arising  from  its  union 
with  the  atmospheric  oxygen,  continue  at  a  bright  red-heat  until  nearly 
consumed. 

1915.  According  to  Berzelius,  the  purity  of  antimony  is  indicated  by  a 


ANTIMONY.  345 

silvery  whiteness,  and  a  granular  or  fine  lamellar  texture;  whereas  the  metal 
otherwise  does  not  excel  tin  in  whiteness,  and  is  coarsely  lamellar,  almost 
as  if  susceptible  of  cleavage.  It  appears  to  me,  that  the  differences  here  re- 
ferred to,  are  dependent,  as  in  other  cases,  on  slowness  or  quickness  of  cool- 
ing.  A  button  which  was  granular  when  taken  from  a  crucible  refrigerated 
in  water, — by  fusion  in  an  iron  mortar  in  which  it  was  prevented  from  cool- 
ing quickly  by  proximity  to  a  fire,  acquired  a  lamellar  texture.  Bad  anti- 
mony looks  like  hornblende  rock  when  broken,  as  to  its  crystalline  texture, 
and  cannot  be  fused  into  a  globule  as  liquid  or  pure.  It  will  not  answer  as 
well  for  the  experiment  of  throwing  on  the  board,  as  the  pure  metal. 

1916.  The  equivalents  of  antimony,  and  of  its  compounds  with  oxygen, 
chlorine,  and  sulphur,  are  as  follows : — 

Antimony,      ........                  .  64 

Sesquioxide,  2  atoms  metal,  3  oxygen,  152 

Antimonious  acid,  2      „         „       4       „  160 

Antimonic  acid,  2      „         „       5       „  168 

Sesquichloride,  2      „         ,,3  chlorine,  236 

Bichloride,  2      „         ,,4       „  272 

Perchloride,  2      „         „       5       „                  -  308 

Sesquisulphide,  2      „         ,,3  sulphur,  176 

Bisulphide,  2      „         ,,4       „  192 

Persulphide,  2      „         ,,5       „  208 

Of  the  Sesquioxide  of  Antimony. 

1917.  Sesquioxide  of  antimony  may  be  obtained  by  ex- 
posing the  metal  to  heat  with  access  of  air;  by  moderately 
roasting  the  sulphide;  or  by  subjecting  the  sesquichloride 
to  water,   in  which   case   a   powder   precipitates,  called 
powder  of  Algaroth,  from  the  name  of  the  physician  who 
first  recommended  it  to  public  attention.     This  powder, 
being  an  oxychloride,  by  digestion  with  the  carbonate  of 
potash,  is  converted  into  the  sesquioxide.     It  may  also  be 
obtained  by  the  reaction  of  the  metal  with  diluted  nitric 
acid,  afterwards  repeatedly  digesting  the  resulting  subsalt 
in  water,  until  this  liquid  no  longer  reddens  litmus.     In 
the  form  in  which  the  sesquioxide  is  obtained  by  heat  and 
air,  it  received  formerly  the  name  of  argentine  flowers  of 
antimony.     When  obtained  from  the  oxychloride,  the  ses- 
quioxide has  a  tinge  of  gray.     If  the  sesquioxide,  as  pro- 
cured by  the  last  mentioned  method,  be  heated,  it  takes 
fire,  and  is  converted  into  antimonious  acid. 

1918.  Sulphuric  acid,  when  cold  or  diluted,  does  not  re- 
act with  antimony,  but,  when  warm  and  concentrated,  is 
partially  decomposed,  evolving  sulphurous  acid,  and  form- 
ing a  sesquioxide  of  the  metal,  with  which  the  undecom- 
posed  acid  combines.     By  water  the  acid  may  be  for  the 

44 


346  INORGANIC  CHEMISTRY. 

most  part  removed  from  this  sulphate,  so  as  to  cause  in  it 
an  excess  of  oxide  so  great  as  to  render  it  competent  for 
the  production  of  tartar  emetic,  by  digestion  with  the  bi- 
tartrate  of  potash.  In  this  case,  the  excess  of  oxide  in  the 
sulphate,  and  the  excess  of  acid  in  the  bitartrate,  unite, 
converting  the  latter  salt  into  the  double  tartrate  of  pot- 
ash and  antimony,  or  tartar  emetic. 

1919.  The  sesquioxide  acts  feebly  both  as  an  acid  and  a 
base.     Combined  with  bitartrate  of  potash,  it  constitutes 
tartar  emetic,  and  is  the  only  compound  of  antimony  with 
oxygen,  which  is  considered  as  medicinal.* 

1920.  Tartar  emetic  may  be  considered  as  consisting  of 

Two  equivalents  of  tartaric  acid,  66  x  2  =  132 

One  of  sesquioxide  of  antimony,  152 

One  of  potash,  48 

Two  of  water,  9x2=    18 

350 

Of  the  Compounds  of  Antimony  with   Oxygen,  of  inferior  importance 

medicinally. 

1921.  Antimonious  acid  is  generated"  by  digesting  antimony  in  nitric 
acid,  evaporating  the  liquid  to  dryness,  and  calcining  the  residue;  or  by 
thoroughly  roasting  the  sulphide  of  antimony  with  access  of  air.     Antimo- 
nious acid  is  white,  tasteless,  infusible,  fixed,  indecomposable  by  heat,  and 
insoluble  in  water. 

1922.  When  nitric  acid  is  added  to  a  solution   of  the  antimonite  of 
potash,  the  antimonious  acid  is  precipitated  in  the  state  of  hydrate.     In  this 
state  it  reddens  litmus  paper. 

1923.  Anhydrous  antimonic  acid  is  obtained  by  subjecting  the  oxychlo- 
ride  to  the  action  of  nitric  acid,  and  afterwards  exposing  the  resulting  mass 
to  a  temperature  of  500°  or  600°,  to  expel  any  excess  of  this  acid.     By  de- 
flagrating the  metal  with  four  times  its  weight  of  nitre,  dissolving  in  water 
the  resulting  mass,  and  afterwards  adding  nitric  acid,  which  combines  with 
the  alkali,  hydrous  antimonic  acid  is  also  procured. 

1924.  Anhydrous  antimonic  acid  is  yellow,  tasteless,  and  insoluble  in 
water.     When  hydrous,  it  is  white,  and  has  the  property  of  reddening 
litmus. 

1925.  Just  at  the  moment  when  certain  antimonites  and  antimoniates, 
subjected  to  a  low  red-heat,  lose  their  water  of  crystallization,  they  give  rise 
to  a  transient  light,  as  vivid  as  would  result  from  a  true  combustion.     Yet 

*  In  the  last  edition  of  this  work,  I  quoted,  on  the  subject  of  tartar  emetic,  an 
article  previously  published  by  Dr.  Bache,  in  the  American  Cyclopedia  of  Practical 
Medicine.  This  article  I  shall  not  introduce  into  this  edition,  because  the  informa- 
tion which  it  comprises,  has  been  given  in  the  United  States'  Dispensatory,  which 
we  owe  to  my  friend  abovementioned,  and  to  my  colleague,  Dr.  Wood.  I  presume 
that  of  this  Dispensatory,  every  matriculant  of  our  university  will  be  provided  with 
a  copy,  as  it  appears  to  rne  to  be  of  itself  equivalent  to  a  choice  library  of  useful 
medical  knowledge. 


ANTIMONY.  347 

they  incur  in  consequence  no  change  in  weight.  Their  colour  is  rendered 
brighter,  and  they  become  less  susceptible  of  decomposition  by  acids.  This 
result  ensues  especially  with  the  antimoniates  of  copper,  cobalt,  and  zinc. 

1926.  The  reaction  of  diluted  nitric  acid  with  antimony,  is  quite  analo- 
gous to  that  already  described  in  the  case  of  bismuth.     According  to  Ber- 
zelius,  a  subnitrate  results,  which  may  be  decomposed  by  water  as  already 
stated,  and  converted  into  a  hydrated  sesquioxide.     But  Thcnard  informs 
us  that,  if  this  metal  be  subjected  to  nitric  acid,  it  is  converted  into  hydrous 
antimonious  acid  (acide  antimonieux  b!anc  et  hydrate).     Possibly  the  dif- 
ference may  arise  from  the  acid  being  in  one  case  concentrated,  in  the  other 
dilute. 

Of  the  Compounds  of  Antimony  with  the  Halogen  Class. 

1927.  Sesquichloride  of  antimony  may  be  obtained,  as  Thenard  alleges, 
by  distilling  the  metal  with  the  bichloride  of  mercury ;  also  by  the  reaction 
of  aqua  regia  with  metallic  antimony,  and  subsequent  distillation  of  the 
resulting  liquid,  collecting  the  product  in  a  fresh  receiver  when  it  becomes 
oleaginous  in  its  consistency.      He  recommends  as   preferable,  however, 
the  action  of  chlorohydric  acid  on  the  sesquisulphide  with  heat,  allowing 
the  sulphydric  acid  gas  to  escape  into  the  fire.   sThe  resulting  liquid  is  to 
be  decanted,  and  concentrated  by  heat  in  a  retort,  until  it  acquires  an 
oleaginous  consistency. 

1928.  The  sesquichloride  has  been  designated  as  the  butter  of  antimony. 
It  is  white,  semitransparent,  very  caustic,  fusible  below  a  boiling  heat,  and 
crystallizable  in  tetrahedrons  by  refrigeration.     It  is  volatile  at  a  heat  be- 
low redness,  and  deliquescent,  so  as  to  be  liquefied  by  exposure  to  air.     It 
has  already  been  mentioned,  that  by  subjecting  this  chloride  to  copious 
affusions  of  water,  (eight  times  its  weight,  according  to  Thenard)  an  oxy- 
chloride  results,  formerly  called  the  powder  of  Algaroth. 

1929.  Bichloride  of  antimony,  agreeably  to  the  last  mentioned  author, 
exists  only  in  combination  with  chlorohydric  acid. 

1930.  Per  chloride  of  antimony  is  formed  by  the  combustion  of  the  metal 
in  chlorine.     It  is  a  yellow  liquid,  sending  forth  thick  fumes  into  the  air, 
with  a  strong  and  disagreeable  smell.     It  attracts  moisture,  and  is,  in  con- 
sequence, at  first  converted  into  a  white  crystalline  mass,  but  afterwards 
liquefied  by  a  further  accession  of  humidity.     Yet  by  exposure  to  a  large 
quantity  of  water  with  heat,  it  is  decomposed,  and  deposits  hydrous  anti- 
monic  acid.     This  process  is  recommended  as  the  best  for  obtaining  this 
compound. 

Of  the  Compounds  of  Antimony  with  Sulphur  and  Selenium. 

1931.  It  has  been  stated  that  antimony  is  procured  principally  from  the 
native  sesquisulphide,  which  is  found  in  the  shops  under  the  name  of  anti- 
mony, the  metal  being  distinguished  as  the  regulus. 

1932.  Sesquisulphide  of  antimony  may  be  formed  from  its  ingredients, 
by  heating  the  metal  in  a  state  of  division  with  sulphur.     It  is  more  fusible 
than  metallic  antimony,  is  crystalline  in  texture,  has  a  metallic  lustre,  and 
a  bluish-gray  colour.     It  may  act  either  as  a  sulphacid,  or  as  a  sulphobase. 
With  the  sulphides  of  the  alkalifiable  metals  it  forms  compounds  which  may 
be  designated  as  hyposulphantimonites. 

1933.  The  sesquisulphide  and  sesquioxide  of  antimony  enter  into  com- 
bination with  each  other  in  different  proportions,  forming  compounds  which 


348  INORGANIC  CHEMISTRY. 

must  be  called  oxysulphides,  consistently  with  the  nomenclature  adopted  in 
the  case  of  the  analogous  compounds  of  oxides  with  chlorides. 

1934.  When  the  sesquisulphide  of  antimony  is  roasted,  in  other  words 
exposed  to  heat  with  access  of  air,  it  becomes  more  or  less  oxidized,  ac- 
cording to  the  duration  of  the  exposure,  the  degree  of  heat,  and  the  supply 
of  air.     If,  after  the  roasting  has  continued  for  some  time,  the  temperature 
be  raised  so  as  to  fuse  the  mass,  a  vitreous  compound  will  result,  the  com- 
position of  which  will  vary  according  to  the  ratio  of  the  oxide  to  the  sul- 
phide, at  the  time  of  effecting  the  fusion.     According  to  Thomson,  when 
the  ratio  of  the  former  to  the  latter  is  as  five  to  one,  the  compound  has  the 
name  of  crocus  of  antimony;  when  the  ratio  is  as  three  to  one,  it  has 
been  called  liver  of  antimony.   'This  name,  however,  is  given  by  Berzelius 
to  a  compound  of  the  sulphides  of  antimony,  with  the  sulphide  of  potas- 
sium or  sulphide  of  sodium. 

1935.  If  the  sulphide  of  antimony,  instead  of  being  poured  out  as  soon 
as  it  is  melted,  be  kept  for  a  great  length  of  time  in  a  state  of  fusion  in  an 
earthen  crucible,  it  derives  a  portion  of  oxide  of  iron  and  silicic  acid  from 
the  crucible,  and  thus  forms  a  transparent  mass  of  a  yellow-hyacinth  co- 
lour, commonly  called  the  glass  of  antimony.     This  glass,  according  to 
Thenard,  is  a  mixture  of  oxysulphide  of  antimony,  with  the  silicates  of  an- 
timony and  iron. 

1936.  By  the  reaction  of  the  sesquisulphide  of  antimony  with  the  alka- 
lies, either  caustic  or  carbonated,  and  either  in  the  wet  or  dry  way,  a  com- 
plicated reaction  ensues,  by  which  the  antimony  of  the  sulphide  is  more  or 
less  oxidized,  the  metal  of  the  alkali  more  or  less  sulphurized;  while  the 
residual  sulphide  of  antimony,  acting  as  a  sulphacid,  combines  more  or  less 
with  the  resulting  sulphobase  of  the  alkalifiable  metal. 

1937.  The  extent  to  which  the  sesquisulphide,  in  the  resulting  sulpho- 
salt,  can  be  retained  by  the  sulphobase  in  an  aqueous  solution,  appears  de- 
pendent upon  temperature.     Hence,  whether  the  sulphosalt  be  produced  in 
the  dry  way  and  dissolved  in  hot  water,  or  be  generated  by  boiling  the  in- 
gredients in  this  liquid,  the  sesquisulphide  precipitates  by  refrigeration. 

1938.  The  precipitate  thus  obtained,  under  the  name  of  kermes  mineral, 
was  so  much  in  vogue  in  France,  about  a  century  ago,  as  to  induce  the  go- 
vernment of  that  country  to  purchase  from  a  surgeon  of  the  name  of  La 
Ligerie,  the  art  of  preparing  it. 

1939.  Thenard  alleges  that  it  appears  from  the  analysis  of  Henry,  Jr., 
that  the  composition  of  kermes  varies  according  to  the  process  employed 
for  its  production.     When  prepared  by  boiling  the  sesquisulphide  in  a  solu- 
tion of  carbonate  of  potash  or  soda,  kermes  may  be  considered  as  a  hy- 
drated  oxysulphide ;  but  when  procured  by  boiling  the  sesquisulphide  in  a 
solution  of  caustic  potash  or  soda,  or  by  fusion  with  them  or  their  carbon- 
ates, and  subsequent  solution  in  hot  water,  it  is  a  hydrated  sesquisulphide, 
containing  very  little  if  any  oxide.  As  obtained  by  precipitation  from  tartar 
emetic  by  sulphydric  acid,  it  is  a  pure  hydrated  sesquisulphide.     After  the 
kermes  has  precipitated,  a  portion  of  the  sesquisulphida  still  remains  in 
union  with  the  sulphobase.     Hence,  on  the  addition  of  an  acid,  a  further 
precipitation  takes  place,  both  of  the  sesquisulphide  of  antimony,  and  the 
sulphur  of  the  sulphobase;  and  these,  either  by  combination  or  mixture, 
constitute  the  golden  sulphur  of  antimony,  another  well  known  pharma- 
ceutical preparation. 

1940.  According  to  the  analysis  of  Henry,  Jr.,  as  quoted  by  Thenard, 


ANTIMONY.  349 

the  composition  of  kermes,  when  obtained  in  the  wet  way  by  carbonate  of 
soda,  is  as  follows  : 

Sesquisulphide  of  antimony,  62.5 

Sesquioxide  of  antimony,        -  -  -  27.4 

Water,  10 

Soda,  .....  a  trace. 

1941.  Upon  the  whole  it  is  inferred  that  the  sesquisulphide,  in  precipi- 
tating by  refrigeration  as  abovementioned,  combines  with  water  in  all  cases ; 
and  that  when  the  process  is  conducted  in  the  wet  way  by  means  of  a  car- 
bonated alkaline  solution,  the  precipitating  hydrated  sesquisulphide  combines 
with  the  sesquioxide,  forming  an  oxysulphide.     The  presence  of  carbonic 
acid  in  union  with  the  alkali  is  requisite,  in  order  to  enable  the  menstruum 
to  form  and  dissolve  while  hot,  a  double  carbonate  of  the  alkali  and  sesqui- 
oxide.    The  latter,  being  thus  taken  up  by  the  aid  of  heat,  subsequently, 
in  consequence  of  the  refrigeration  and  its  affinity  for  the  hydrated  ses- 
quisulphide, precipitates  in  combination  with  this  sulphide,  as  already  men- 
tioned. 

1942.  The  officinal  preparation,  called  precipitated  sulphuret  of  antimony, 
is  obtained  by  adding  diluted  sulphuric  acid  to  a  solution  of  the  sesquisul- 
phide of  antimony  in  a  hot  solution  of  caustic  potash.     A  precipitate  re- 
sults which  may  be  considered  as  a  mixture  of  kermes  mineral  and  golden 
sulphur  of  antimony. 

1943.  Bisulphide  of  antimony  is  obtained,  according  to  Thomson,  by 
dissolving  antimonious  acid  in  chlorohydric  acid,  and  subjecting  the  result- 
ing liquid  to  sulphydric  acid.     I  infer  that  four  atoms  of  chlorohydric  acid, 
acting  on  two  atoms  of  antimony,  in  union  with  four  atoms  of  oxygen,  will 
be  productive  of  a  bichloride,  and  that  this  will  be  converted  into  a  bisulphide 
by  reaction  with  the  sulphydric  acid. 

1944.  The  bisulphide,  being  resolvable  into  the  sesquisulphide  and  sul- 
phur by  heat,  cannot  be  produced  by  the  fusion  of  its  constituents.     It  is  of 
an  orange-red  colour,  and  acts  as  a  sulphacid. 

1945.  Per  sulphide  of  antimony  is  obtained  by  passing  sulphydric  acid 
through  a  diluted  solution  of  the  pe'rchloride  of  this  metal,  to  which  tartaric 
acid  has  previously  been  added.  Its  colour  resembles  that  of  the  bisulphide, 
though  somewhat  paler. 

1946.  The  selenide  of  antimony  is  obtained  by  heating  this  metal  with 
selenium.    Like  the  sulphide,  it  is  capable  of  entering  into  combination  with 
the  oxide. 

Experimental  Illustrations. 

1947.  Antimony  and  its  sulphide,  exhibited,  and  exposed 
to  the  blowpipe:  also,  the  crystals  and  solution  of  tartar 
emetic.  Kermes  mineral,  golden  sulphur,  and  precipitated 
sulphuret  of  antimony,  exhibited.  Antimony,  subjected  to 
acids.  Kermes  mineral,  precipitated  from  a  solution  of 
tartar  emetic  by  sulphydric  acid. 


350  INORGANIC  CHEMISTRY. 

SECTION  XIII. 

OF  METALS  PROPER  OF  MINOR  IMPORTANCE. 

OF  PALLADIUM. 

1948.  Besides  iron,  copper,  and  lead,  four  metals,  palladium,  rhodium, 
iridium,  and  osmium,  are  found  in  union  with,  or  accompanying  the  native 
grains  of  platinum,  as  imported  from  South  America.     Accordingly,  if  a 
portion  of  that  assemblage  of  metallic  particles,  of  which  the  native  grains 
of  platinum  above  mentioned  form  the  principal  part,  be  digested  in  aqua 
regia,  the  platinum,  together  with  the  palladium,  rhodium,  copper,  and  lead, 
will  be  dissolved ;  while  a  black  powder  will  be  left,  consisting  of  osmium 
and  iridium  in  combination  with  each  other. 

1949.  The  platinum  having  been  precipitated  from  this  solution  (1587) 
by  the  chloride  of  ammonium,  any  palladium  which  it  may  contain,  with 
all  of  the  other  noble  metals  which  may  be  present,  may  be  precipitated  by 
a  bright  plate  of  zinc.     The  resulting  precipitate,  after  being  digested  with 
chlorohydric  acid  and  washed  with  water,  should  be  redissolved  in  aqua  regia. 
Any  excess  of  acid  should  be  neutralized  by  carbonate  of  soda.     From  the 
neutralized  solution  the  palladium  may  be  thrown  down  by  a  solution  of  bicy- 
anide  of  mercury  which  yields  its  cyanogen  to  the  palladium.     An  insolu- 
ble cyanide  of  palladium,  being  thus  formed,  precipitates.     By  the  aid  of 
heat   this  precipitate   is  decomposed,  the  cyanogen  is  expelled,   and    the 
metal  is  isolated. 

1950.  Mr.  Cloud,  of  the  United  States'  mint,  found  this  metal  in  a  native 
alloy  of  gold  which  was  brought- from  Brazil. 

1951.  The  colour  of  palladium  appears  to  me  to  have  a  minute  degree 
of  tendency  towards  the  rosy  hue  of  bismuth,  not  being  quite  so  pale  as 
platinum,  which  it  otherwise  much  resembles  in  appearance.     It  is  however 
more  fusible,  rather  harder,  and  more  elastic.     Its  specific  gravity,  also,  is 
much  less,  being  about  11.5.     It  is  malleable  and  ductile,  and  insusceptible 
of  oxidizement  by  heat  and  air. 

OF  RHODIUM. 

1952.  After  the  palladium  has  been  precipitated,  the  solution  contains  the 
chloracids  of  rhodium,  mercury,  and  several  other  metals,  united  with  the 
chloride  (or  chlorobase)  of  sodium,  resulting  from  the  carbonate  of  soda, 
employed  as  abovementioned  to    neutralize  the  excess  of  acid.      There 
is  likewise  present   a  portion   of  the   undecomposed  bicyanide   of  mer- 
cury.    Under  these  circumstances,  chlorohydric  acid  must  be  added,  in 
order  to  convert  this  bycyanide  into  a  bichloride,  and  the  solution  after- 
wards must  be  evaporated  to  dryness.     The  resulting  mass  should  then  be 
washed  with  alcohol,  which  dissolves  all  the  chlorosalts  of  sodium  present, 
except  the  chlorhodiate.     Rhodium  is  obtained  from  this  by  heating  it  in  a 
current  of  hydrogen,  which  removes  the  chlorine  combined  with  the  metal- 
the  chloride  of  sodium  being  removed  by  water. 

1953.  Rhodium,  according  to  Berzelius,  cannot  be  fused,  except  by  sub 
jecting  it,  when  in  the  state  of  a  sulphide  or  arseniuret,  to  an  intense  heat. 
After  fusion,  it  resembles  platinum  in  appearance.     Its  salts  are  generally 
either  red  or  yellow.     It  is  named  from  its  chloride,  which  is  rose-red. 


IRIDIUM. OSMIUM. NICKEL.  351 


OF  IRIDIUM. 

1954.  When  the  black  powder,  consisting  of  the  osmiuret  of  iridium, 
which  remains  as  above  stated,  after  we  have  subjected  the  crude  grains  of 
platinum  to  aqua  regia,  is  heated  with  soda,  an  osmiate  of  soda  is  formed, 
which  may  be  removed  by  dissolving  it  in  water.     The  remaining  mass  is 
to  be  treated  with  aqua  regia,  in  which  the  iridium,  converted  into  a  chlo- 
ride, dissolves.     By  repeating  this  process,  the  whole  is  finally  converted 
into  solutions  of  chloride  of  iridium,  and  of  osmiate  of  soda. 

1955.  From  the  former,  crystals  of  the  chloride  of  iridium  may  be  ob- 
tained by  evaporation,  which,  on  exposure  to  a  strong  heat,  yield  metallic 
iridium. 

1956.  Iridium  resembles  platinum  in  appearance,  and  is  probably,  ac- 
cording to  Thomson,  the  heaviest  of  the  metals.     When  heated  in  con- 
tact with  air  nearly  to  redness  it  is  oxidized,  but  on  the  application  of  a 
higher  temperature  it  is  again  restored  to  the  metallic  state.    Thenard,  how- 
ever, states,  that  iridium  which  has  been  subjected  to  a  strong  heat,  is  abso- 
lutely insusceptible  of  oxidizement  by  the  air  at  any  temperature. 

1957.  Iridium  is  said  to  be  the  most  refractory  of  the  metals,  having 
never  been  fused  until  it  was  placed  between  the  poles  of  Children's  large 
galvanic  battery.     It  was  then  converted  into  a  globule,  possessing  metallic 
whiteness  and  lustre. 

OF  OSMIUM. 

1958.  Osmic  acid  may  be  obtained  by  distilling  the  solution  of  osmiate 
of  soda,  procured  as  above  described,  with  nitric  acid  at  a  gentle  heat. 
The  osmic  acid  passes  over,  and  may  afterwards  be  reduced  by  the  addi- 
of  chlorohydric  acid  and  mercury.     It  is,  however,  alloyed  with  mercury, 
and  mingled  with  the  chloride  of  this  metal.     These  may  be  sublimed  by  a 
gentle  heat,  leaving  pure  metallic  osmium. 

1959.  Osmium  obtained  in  this  way,  is  of  a  grayish-black  colour;  but 
if  a  portion  of  the  volatilized  oxide  be  made  to  pass  with  a  current  of  hydro- 
gen through  a  glass  tube,  the  osmium-  is  deposited  in  the  form  of  a  ring  of 
metallic  brilliancy,  and  of  a  white  colour.     It  is  so  difficult  to  fuse  in  close 
vessels,  and  so  liable  to  be  volatilized  when  heated  in  the  air,  that  it  has 
only  been  obtained  in  powder,  or  in  minute  friable  masses.     Its  volatility 
in  the  air  arises  from  its  great  susceptibility  of  oxidizement,  and  the  vola- 
tility of  its  oxide,  the  fumes  of  which  are  pungent. 

OF  NICKEL. 

1960.  A  mineral  had  been  known  to  the  German  miners  by  the  name 
of  kupfer  nickel,  or  false  copper.     About  the  middle  of  the  last  century, 
Cronstedt  alleged  the  existence,  in  this  mineral,  of  a  peculiar  metal.  Never- 
theless, the  metal,  thus  indicated,  was  considered  by  many  chemists  as  an 
alloy  of  copper  with  iron.      About  1775,  Bergmann  confirmed,  by  an 
analysis,  the  allegation  of  Cronstedt. 

1961.  Kupfer  nickel  is  principally  an  arseniuret  of  nickel,  but  contains, 
also,  sulphur,  iron,  cobalt,  and  copper.     Nickel  is  extricated  from  it  by  a 
tedious  and  intricate  process. 

1962.  Nickel  is  of  a  white  colour,  difficult  of  fusion,  malleable  and  not  easi- 
ly oxidized  by  the  air.     It  is  so  susceptible  of  the  magnetic  influence  that  a 
permanent  magnet  may  be  made  of  it.      If  sufficiently  abundant,  nickel 
would  be  very  valuable  in  the  arts.     A  white  alloy  of  this  metal  with  cop- 


352  INORGANIC  CHEMISTRY. 

per,  had  long  been  known  in  China,  under  the  name  of  packfong.  Of  late 
this  alloy  has  been  brought  into  use  in  Europe,  under  the  name  of  argen- 
tane  or  German  silver.  It  serves  for  pencil  cases  and  many  analogous 
uses  nearly  as  well  as  ^  silver.  It  combines  with  oxygen,  chlorine,  iodine, 
cyanogen,  sulphur,  and  the  metals.  Its  oxides  are  soluble  in  the  acids, 
and  in  their  habitudes  are  much  like  those  of  copper.  The  solubility  of  its 
protoxide  in  caustic  ammonia,  is  an  important  means  of  separating  nickel 
from  its  alloys. 

OF  CADMIUM. 

1963.  This  metal  has  been  derived  only  from  the  ores  of  zinc.     During 
the  reduction  of  calamine,  a  substance  sublimes  which  yields  from  12  to  20 
per  cent,  of  cadmium. 

1964.  A  solution  of  the  ore  in  sulphuric  acid,  being  impregnated  with 
sulphydric  acid,  the  cadmium  precipitates  in  the  state  of  sulphide,  mixed 
with  a  little  sulphide  of  zinc,  and  sometimes  with  sulphide  of  copper.  When 
these  sulphides  are  exposed  to  chlorohydric  acid,  the  sulphur  unites  with 
the  hydrogen  of  the  acid  and  escapes,  and  they  are  converted  into  chlorides. 
Carbonate  of  ammonia  being  added  to  the  resulting  solution  of  cadmium 
and  zinc,  a  carbonate  of  cadmium  is  alone  precipitated.     From  this,  the 
metal  may  be  obtained  by  means  of  heat  and  charcoal. 

1965.  Cadmium  is  almost  as  white  as  tin,  is  without  odour  or  taste, 
very  brilliant,  and  susceptible  of  a  fine  polish.     It  is  crystallizable,  mallea- 
ble, and  ductile,  and  so  soft  as  to  yield  easily  to  a  file  or  knife.    Its  specific 
gravity  is  8.6  nearly.     It  is  too  scarce  to  be  usefully  applied.     It  fuses  and 
volatilizes  at  a  very  low  temperature. 

OF  CHROMIUM. 

1966.  This  metal  is  found  in  nature  only  in  the  state  of  an  acid  and  of 
an  oxide,  generally  united  with  lead  or  iron,  though  in  some  instances  pure. 
It  was  in  the  native  chromate  of  lead,  found  usually  in  crystals  which  rival 
the  ruby  in  colour,  that  this  metal  was  discovered  by  Vauquelin.     A  com- 
pound of  the  sesquioxides  of  chromium  and  iron,  called  incorrectly  chro- 
mate of  iron,  is  found  plentifully  in  this  country.    The  sesquioxide  of  chro- 
mium, when  intensely  heated  with  charcoal,  is  reduced,  but  not  without 
great  difficulty. 

1967.  The  presence  of  chromium  in  a  mineral  may  be  detected  by  the 
fusion  of  a  minute  portion  before  the  blowpipe  with  borax,  or  preferably, 
with  the  ammoniacal  phosphate  of  soda.    In  thi§  way,  a  globule  of  a  beauti- 
ful emerald  green  results,  which  preserves  its  colour  either  in  the  oxidizing, 
or  reducing  flame.     By  these  characteristics  it  may  be  distinguished  from 
copper  or  uranium;  since  uranium  communicates  a  green  hue  only  in  the 
reducing  flame,  copper  only  in  the  oxidizing  flame. 

1968.  Chromium  is  a  hard,  brittle  metal,  of  a  grayish- white  colour,  and 
very  difficult  to  fuse.     Its  specific  gravity  is  5.9.     Its  equivalent  is  28.     It 
forms  with  oxygen  a  sesquioxide  and  an  acid.     The  compound,  heretofore 
considered  as  a  deutoxide,  proves  to  be  a  mixture  of  sesquioxide  and  chro- 
mic acid. 

1969.  The  sesquioxide  of  chromium  is  easily  obtained  by  exposing  the 
chromate  of  mercury  to  heat,  by  which  the  mercurial  oxide  and  a  portion 
of  the  oxygen  of  the  acid  are  expelled,  while  the  sesquioxide  remains  in  the 
form  of  a  grass-green  powder.     It  may  also  be  obtained  in  the  state  of 
hydrate,  by  mixing  solutions  of  the  bichromate  of  potash,  and  persulphide 


CHROMIUM.  353 

of  potassium.  This  sesquioxide  is  of  a  beautiful  green  colour,  which  it 
communicates  to  some  of  its  compounds,  being  in  fact  the  colouring  matter 
of  the  emerald.  It  appears  to  act  both  as  an  acid  and  a  base. 

1970.  In  common  with  zirconia  and  oxide  of  titanium,  the  sesquioxide 
of  chromium,  when  obtained  from  the  hydrate  by  expelling  the  water  by  a 
gentle  heat,  becomes  incandescent  at  a  certain  elevation  of  temperature,  in 
a  way  which  is  altogether  unaccountable.     At  the  same  time  it  loses  its 
property  of  solubility  in  acids  which  it  before  possessed. 

1971.  Chromic  acid  may  be  procured  by  the  following  process: — Let 
four  parts  of  the  chromate  of  lead  be  mixed  with  three  parts  of  fluoride  of 
calcium,  both  finely  pulverized.     Then  let  five  parts  of  sulphuric  acid,  de- 
prived of  water  as  far  as  possible  by  boiling,  be  added,  and  let  the  whole 
be  distilled  in  a  leaded  or  platinum  alembic  at  a  gentle  heat.     A  red  gas 
will  be  developed,  producing  in  the  air  yellow  fumes.     This  red  gas  is  a 
fluoride  of  chromium,  which,  on  being  passed  into  water,  is  converted  into 
fluohydric  and  chromic  acids.     The  former  may  be  expelled  by  evapora- 
tion, the  chromic  acid  remaining  in  a  state  of  purity. 

1972.  If,  instead  of  causing  the  gaseous  fluoride  of  chromium  to  enter 
water,  it  be  conducted  by  means  of  a  tube  into  a  receptacle  of  platinum, 
closed  with  moistened  paper,  and  having  a  small  quantity  of  water  at  the 
bottom,  the  gas  will  be  decomposed  by  the  aqueous  vapour,  mingled  with 
the  air  of  the  vessel,  and  will  deposite  first  about  the  mouth  of  the  tube,  and 
afterwards  throughout  the  vessel,  a  flocky  vegetation,  consisting  of  ruby- 
red  crystals  of  chromic  acid. 

1973.  Chromic  acid  is  solid,  soluble  in  water,  and  capable  of  reddening 
litmus.     It  is  decomposed  by  heat,  and  by  most  substances  which  possess 
an  affinity  for  oxygen.     It  possesses  an  acid  and  astringent  taste,  and  a 
ruby-red  colour,  which  it  communicates  to  some  of  its  compounds,  as  al- 
ready noticed  in  the  case  of  native  chromate  of  lead.    It  forms  striking  and 
beautiful  precipitates  with  various  metals.     That  which  it  produces  with 
lead,  is  of  a  splendid  orange-yellow,  and  is  much  used  as  a  pigment.     The 
colour  of  the  streak  left  by  the  red  crystals  above  described,  when  rubbed 
upon  a  hard  surface,  is  likewise  orange-yellow ;  and  the  same  change  en- 
sues from  pulverization.     The  bichromate  of  potash  is  poisonous,  and  no 
doubt  the  acid  and  its  compounds  are  generally  poisons.     Chromic  acid 
creates  a  stain  upon  the  skin  which  cannot  be  removed  by  water,  unless  it 
contain  an  alkali.     Where  there  is  any  abrasion  of  the  cuticle,  the  presence 
of  this  acid  will  induce  a  painful  ulcer.     Hence  the  sores  to  which  dyers 
are  exposed  who  employ  bichromate  of  potash  as  a  dye-stuff.     These  sores 
have  been  alleged  to  arise  even  from  exposure  to  the  vapours  or  fumes  of 
this  acid.     When  received  into  the  stomach,  chromic  acid  is  a  virulent 
poison.     Dr.  Ducatel  informs  us  of  the  case  of  a  labourer  who  died  in  five 
hours,  after  drawing  into  his  mouth  from  a  syphon,  a  solution  of  bichromate 
of  potash ;  although  he  was  under  the  impression  that,  by  spitting,  he  had 
avoided  taking  it  into  his  stomach. 

1974.  Dr.  Ducatel  suggests  an  alkaline  solution  as  the  best  antidote  for  this 
poisonous  salt ;  as  he  ascribes  its  activity  mainly  to  the  excess  of  acid.    An 
instance  of  a  criminal  prosecution  for  poisoning  by  this  bichromate,  is  men- 
tioned, which  failed  from  that  ignorance  of  its  deleterious  properties  which 
Dr.  Ducatel's  communication  must  tend  to  correct.* 

*  See  Journal  of  the  Philadelphia  College  of  Pharmacy,  for  January,  1834,  page 
272,  vol.  5. 

45 


354  INORGANIC   CHEMISTRY. 


OF  COBALT. 

1975.  This  metal  is  found  in  nature,  principally  in  union  with  arsenic* 
By  the  exposure  of  the  mineral,  thus  containing  it,  to  heat,  with  access  of 
air,  the  arsenic  is  oxidized  and  expelled,  and  the  cobalt  is  reduced  to  the 
state  of  an  impure  oxide,  called  zaffre.     By  fusion  with  the  alkali  and 
sand,  zaffre  yields  a  beautiful  blue  glass,  which,  when  pulverized,  forms 
the  blue  vitreous  powder  called  smalt. 

1976.  Cobalt  may  be  obtained  from  its  oxide,  by  intense  ignition  with 
charcoal,  or  by  subjecting  it,  while  ignited  in  a  porcelain  tube,  to  a  current 
of  hydrogen. 

1977.  Cobalt  is  brittle,  of  a  grayish-white  colour,  and  feeble  lustre.    Its 
specific  gravity  is  8.5  nearly.    It  requires  a  high  temperature  for  its  fusion. 

OF  COLUMB1UM. 

1978.  A  metal  discovered  by  Hatchett,  in  1801,  in  a  mineral  obtained 
from  America,  received  the  name  of  columbium.    It  was  afterwards  detected 
by  Ekeberg  in  two  Swedish  minerals,  called  tantalite  and  yttrotantalite ; 
and  being  supposed  to  be  a  new  metal,  was  called  tantalum.     Wollaston 
afterwards  demonstrated  the  identity  of  tantalum  with  columbium. 

1979.  This  metal  is  found  in  the  state  of  an  acid,  combined  either  with 
manganese  and  a  little  iron,  or  with  yttria.     Both  combinations  are  very 
rare.     It  may  be  reduced  by  heating  the  fluocolumbate  of  potassium,  or 
fluoride  of  columbium  and  potassium,  with  potassium. 

1980.  Columbium  is  a  brittle  metal,  of  an  iron-gray  colour,  having  the 
metallic  lustre.     It  is  infusible  by  the  most  intense  heat  of  the  forge  fire. 

OF  MANGANESE. 

1981.  Manganese  exists  in  nature  principally  in  the  state  of  a  black 
bioxide;  rarely  in  that  of  phosphate,  sometimes  in  the  state  of  sulphide. 
The  utility  of  this  oxide,  as  a  source  of  oxygen  gas,  as  an  ingredient  in 
glass,  and  as  one  of  the  agents  for  evolving  chlorine,  has  been  noticed.  (663.) 
The  metal  is  obtained  by  heating  the  oxide  intensely  with  charcoal  or 
potassium.     It  is  gray,  brittle,  hard,  and  scarcely  fusible  by  the  highest 
heat  of  the  forge,  or  air  furnace.     In  the  metallic  state,  it  has  not  been 
applied  to  any  useful  purpose. 

1982.  Manganese  is  remarkable  for  the  number  of  compounds  which  it 
forms  with  oxygen.    Besides  a  protoxide,  sesquioxide,  and  bioxide,  it  forms 
two  acids,  the  manganic,  and  oxymanganic  or  permanganic  acids.     The 
salts  of  the  latter  detonate  with  combustibles. 

1983.  When  the  black  oxide  (bioxide)  is  fused  with  nitrate  of  potash,  a 
compound  results,  of  which  the  aqueous  solution  becomes  blue,  violet,  and 
red,  and  finally  colourless,     Hence  this  compound  has  been  called  chame- 
leon mineral.     These  colours  appear  to  be  produced  by  the  conversion  of 
the  manganate  of  potash,  into  an  oxymanganate. 

OF  MOLYBDENUM. 

1984.  This  metal  is  only  found  in  the  state  of  sulphide,  resembling  plum- 
bago, or  united  with  oxygen  and  lead  in  the  state  of  molybdate  of  lead. 
From  the  sulphide  it  is  obtained  by  ebullition  with  nitric  acid,  which  acidifies 
both  the  sulphur  and  metal.     The  sulphuric  acid  being  expelled  by  heat, 
the  molybdic  acid  is  decomposed  by  intense  ignition  with  charcoal. 


TITANIUM. TUNGSTEN. URANIUM. CERIUM,   &C.      355 

1985.  As  from  the  difficulty  of  fusing  it,  molybdenum  has  been  only 
obtained  in  small  grains,  its  properties  are  but  little  known.     It  is  alleged 
to  have  a  high  degree  of  metallic  lustre,  and  a  white  colour. 

OF  TITANIUM. 

1986.  Titanium,  like  many  other  metals,  is  only  interesting  as  an  item 
in  the  knowledge  which  human  skill  and  assiduity  have  accumulated,  with 
respect  to  the  materials  of  the  globe  which  we  inhabit.     It  is  obtained  by 
separating  the  oxide  from  the  substances  with  which  it  is  naturally  mixed, 
and  heating  it  intensely  with  charcoal. 

1987.  Titanium  was  first  ascertained  to  exist  in  the  state  of  oxide,  by 
Mr.  Gregor,  in  a  mineral  called  menachanite.    It  was  subsequently  detected 
in  the  metallic  state  by  Dr,  Wollaston,  in  minute  cubic  crystals,  in  the  slag 
found  at  the  bottom  of  a  smelting  furnace. 

1988.  These  crystals  were  conductors  of  electricity,  of  the  specific  gra- 
vity of  5.3,  and  hard  enough  to  scratch  rock  crystal.    In  colour  and  lustre, 
they  were  like  burnished  copper.     They  resisted  the  action  of  nitric  acid 
and  aqua  regia,  but  were  oxidized  by  being  heated  with  nitre. 

OF  TUNGSTEN. 

1989.  In  1781,  Scheele,  having  analysed  a  stone  known  by  the  name 
of  tungsten,  or  heavy  stone,  concluded  that  it  consisted  of  an  acid  united 
with  lime.     Bergmann  suspected  the  radical  of  this  acid  to  be  metallic. 
Messrs.  D'Elhuyart  verified  his  conjecture,  by  heating  tungstic  acid  intensely 
with  charcoal. 

1990.  Tungsten  is  grayish-white,  brilliant,  and  extremely  difficult  to 
fuse.     Its  specific  gravity  is  17. 6- 

OF  URANIUM. 

1991.  Uranium  is  a  rare  production  in  nature,  and  has  scarcely  been 
found  in  sufficient  quantities  for  an  adequate  observation  of  its  properties. 
It  is  stated  to  have  the  metallic  lustre,  a  reddish-brown  colour,  to  be  crys- 
talline in  its  structure,  and  scarcely  susceptible  of  fusion  by  the  heat  of  a 
forge  fire. 

OF  CERIUM. 

1992.  Cerium,  according  to  Vauquelin,  who  was  unable  to  obtain  it  in 
masses  larger  than  the  head  of  a  common  pin,  is  a  white  brittle  metal. 
From  some  experiments  made  by  Children  and  Thomson,  it  appears  to  be 
susceptible  of  volatilization. 

OF  VANADIUM. 

1993.  Vanadium  was  discovered,  in  1801,  by  Del  Rio,  in  a  lead  ore 
from  Zimapan,  in  Mexico ;  but  Collet  Descotils,  to  whom  the  mineral  was 
sent,  having  made  some  new  experiments  upon  it,  pronounced  it  to  be  an 
ore  of  chromium.     Del  Rio  himself  having  acquiesced  in  this  opinion,  it 
was  generally  adopted  until  1830,  when  Sefstrom  discovered  this  metal 
again  in  a  variety  of  Swedish  iron,  and  in  the  scoria  of  the  forge  at  which 
the  iron  had  been  wrought. 

1994.  Vanadium  resembles  molybdenum  in  appearance;  and  in  its  pro- 
perties lies  between  that  metal  and  chromium. 


356  INORGANIC  CHEMISTRY. 

Experimental  Illustrations. 

1995.  Exhibition  of  various  specimens  of  the  metals 
mentioned  in  the  preceding  pages.  Magnetic  influence  of 
nickel,  demonstrated.  Solutions  of  silver,  mercury,  and 
lead,  precipitated  by  chromate  of  potash.  Sesquioxide  of 
chromium,  evolved  by  heating  the  chromate  of  mercury. 
Exhibition  of  the  fluoride  of  chromium.  Effects  of  co- 
balt, also  of  manganese,  upon  vitrified  borax. 


SALTS. 

1996.  In  my  preliminary  exposition  of  the  grounds  of  the  classification 
and  nomenclature  adopted  in  this  work,  I  alleged  the  word  salt  to  be  insus- 
ceptible of  any  definition  consistent  with  the  use  made  of  it  by  Berzelius  as 
a  basis  of  nomenclature.     As  the  reader,  who  has  studied  this  work  so  far, 
as  to  have  reached  this  page  in  due  course,  should  have  acquired  a  know- 
ledge of  the  facts  upon  which  the  above  cited  allegation  was  founded,  I  will 
here  quote  the  language  in  which  those  facts  were  stated,  and  my  inferences 
from  them  justified. 

1997.  The  most  striking  feature  in  the  nomenclature  of  Berzelius,  is  the 
formation  of  two  classes  of  bodies;  one  class  called  "  halogene"  or  salt 
producing,  because  they  are  conceived  to  produce  salts  directly ;  the  other 
called  "  amphigene,"  or  both  producing,  being  productive  both  of  acids  and 
bases,  and  of  course  indirectly  of  salts.     To  render  this  division  eligible,  it 
appears  to  me  that  the  terms  acid,  base,  and  salt,  should,  in  the  first  place, 
be  strictly  defined.     Unfortunately  there  are  no  terms  in  use,  more  broad, 
vague,  and  unsettled  in  their  meaning.    Agreeably  to  the  common  accepta- 
tion, chloride  of  sodium  is  pre-eminently  entitled  to  be  called  a  salt ;  since 
in  common  parlance,  when  no  distinguishing  term  is  annexed,  salt  is  the 
name  of  that  chloride.     This  is  quite  reasonable,  as  it  is  well  known  that 
the  genus  was  named  after  this  compound.     Other  substances,  having  in 
their  obvious  qualities  some  analogy  with  chloride  of  sodium,  were,  at  an 
early  period,  readily  admitted  to  be  species  of  the  same  genus;  as,  for  in- 
stance, Glauber's  salt,  Epsom  salt,  sal  ammoniac.     Yet  founding  their  pre- 
tensions upon  similitude  in  obvious  qualities,  few  of  the  substances  called 
salts,  in  the  broader  sense  of  the  name,  could  have  been  admitted  into  the 
class.     Insoluble  chlorides  have  evidently,  on  the  score  of  properties,  as 
little  claim  to  be  considered  as  salts,  as  insoluble  oxides.     Luna  cornea, 
plumbum  corneum,  butter  of  antimony,  and  the  fuming  liquor  of  Libavius, 
are  the  appellations  given  respectively  to  chlorides  of  silver,  lead,  antimony, 
and  tin,  which  are  quite  as  deficient  of  the  saline  character  as  the  corre- 
sponding compounds  of  the  same  metal  with  oxygen.     Fluoride  of  calcium 
(fluor  spar)  is  as  unlike  a  salt  as  lime,  the  oxide  of  the  same  metal.     No 
saline  quality  can  be  perceived  in  the  soluble  "  haloid  salts,"  so  called  by 
Berzelius,  while  free  from  water ;  and  when  a  compound  of  this  kind  is 


SALTS.  357 

moistened,  even  by  contact  with  the  tongue,  it  may  be  considered  as  a  salt 
formed  of  an  hydracid  and  an  oxybase,  produced  by  a  union  of  the  hydro- 
gen of  the  water  with  the  halogene  element,  and  of  the  oxygen  with  the 
radical.  It  is  admitted  by  Berzelius,  vol.  3,  page  330,  that  it  cannot  be 
demonstrated  that  the  elements  of  the  water,  and  those  of  an  haloid  salt, 
dissolved  in  that  liquid,  do  not  exist  in  the  state  of  an  hydracid  and  an  oxy- 
base, forming  a  salt  by  their  obvious  union. 

1998.  On  the  other  hand,  if,  instead  of  qualities,  we  resort  to  composi- 
tion as  the  criterion  of  a  salt ;  if,  as  in  some  of  the  most  respectable  che- 
mical treatises,  we  assume  that  the  word  salt  is  to  be  employed  only  to  de- 
signate compounds  consisting  of  a  base  united  with  an  acid,  we  exclude 
from  the  class  chloride  of  sodium,  and  all  other  "  haloid  salts,"  and  thus 
overset  the  basis  of  the  distinction  between  "  halogene"  and  "  amphigene" 
elements. 

1999.  Moreover,  while  thus  excluding  from  the  class  of  salts,  substances 
which  the  mass  of  mankind  will  still  consider  as  belonging  to  it,  we  assem- 
ble under  one  name  combinations  opposite  in  their  properties,  and  destitute 
of  the  qualities  usually  deemed  indispensable  to  the  class.     Thus  under  the 
definition  that  every  compound  of  an  acid  and  a  base,  is  a  salt,  we  must 
attach  this  name  to  marble,  gypsum,  felspar,  glass,  and  porcelain,  in  com- 
rrlon  with  Epsom  salt,  Glauber's  salt,  vitriolated  tartar,  pearlash,  &c.     But 
admitting  that  these  objections  are  not  sufficient  to  demonstrate  the  absurdity 
of  defining  a  salt,  as  a  compound  of  an  acid  and  a  base,  of  what  use  could 
such  a  definition  be,  when,  as  I  have  premised,  it  is  quite  uncertain  what  is 
an  acid,  or  what  is  a  base.     To  the  word  acid,  different  meanings  have 
been  attached  at  different  periods.     The  original  characteristic  sourness  is 
no  longer  deemed  essential !  Nor  is  the  effect  upon  vegetable  colours  treated 
as  an  indispensable  characteristic.     And  as  respects  obvious  properties,  can 
there  be  a  greater  discordancy,  than  that  which  exists  between  sulphuric 
acid,  and  rock  crystal;  between  vinegar,  and  tannin;  or  between  the  vola- 
tile, odoriferous,  liquid  poison,  which  we  call  prussic  acid,  and  the  inodo- 
rous, inert,  concrete  material  for  candles,  called  margaric  acid  ? 

2000.  While  an  acid  is  defined  to  be  a  compound  capable  of  forming  a 
salt  with  a  base,  a  base  is  defined  to  be  a  compound  that  will  form  a  salt 
with  an  acid.     Yet  a  salt  is  to  be  recognised  as  such,  by  being  a  compound 
of  the  acid  and  base,  to  which,  as  I  have  stated,  it  is  made  an  essential 
mean  of  recognition. 

2001.  An  attempt  to  reconcile  the  definitions  of  acidity  given  by  Berze- 
lius, with  the  sense  in  which  he  uses  the  word  acid,  will,  in  my  apprehen- 
sion, increase  the  perplexity. 

2002.  It  is  alleged  in  his  Traite,  page  1,  Vol.  II.,  "that  the  name  of 
acid  is  given  to  silica,  and  other  feeble  acids,  because  they  are  susceptible 
of  combining  with  the  oxides  of  the  electropositive  metals,  that  is  to  say, 
with  salifiable  bases,  and  thus  to  produce  salts,  which  is  precisely  the 
principal  character  of  acids."     Again,  Vol.  I.,  page  308,  speaking  of  the 
halogene  elements,  he  declares  that  "  their  combinations  with  hydrogen,  are 
not  only  acids,  but  belong  to  a  series  the  most  puissant  that  we  can  employ 
in  chemistry ;  and  in  this  respect  they  rank  as  equals  with  the  strongest  of 
the  acids,  into  which  oxygen  enters  as  a  constituent  principle."  And  again, 
Vol.  II.,  page  162,  when  treating  of  hydracids  formed  with  the  halo^ene 
class,  he  alleges  "  The  former  are  very  powerful  acids,  truly  acids,  and 
perfectly  like  the  oxacids  ;  but  they  do  not  combine  with  salifable  bases  ; 
on  the  contrary,  they  decompose  them,  and  produce  haloid  salts." 


358  INORGANIC  CHEMISTRY. 

2003.  In  this  paragraph,  the  acids  in  question  are  represented  as  pre- 
eminently endowed  with  the  attributes  of  acidity,  while  at  the  same  time 
they  are  alleged  to  be  destitute  of  his  "principal  character  of  acids"  the 
property  of  combining  with  salifiable  bases. 

2004.  In  page  41,  (same  volume,)  treating  of  the  acid  consisting  of  two 
volumes  of  oxygen  and  one  of  nitrogen,  considered  by  chemists  generally 
as  a  distinct  acid,  Berzelius  uses  the  following  language.     "  If  I  have  not 
coincided  in  their  view,  it  is  because,  judging  by  what  we  know  at  present, 
the  acid  in  question  cannot  combine  with  any  base,  either  directly  or  indi- 
rectly; that  consequently  it  does  not  give  salts,  and  that  salifiable  bases  de- 
compose it  always  into  nitrous  acid,  and  nitric  oxide  gas.     It  is  not  then  a 
distinct  acid,  and  as  such,  ought  not  to  be  admitted  in  the  nomenclature." 
Viewing  these  passages  with  all  that  deference  which  I  feel  for  the  produc- 
tions of  the  author,  I  am  unable  to  understand  upon  what  principle  the  ex- 
clusion of  nitrous  acid  from  the  class  of  acids,  can  be  rendered  consistent 
with  the  retention,  in  that  class,  of  the  compounds  formed  by  hydrogen 
with  "  halogene"  elements. 

2005.  It  is  certainly  to  be  regretted  that  there  should  be  so  much  diffi- 
culty in  giving  a  precise  meaning  to  a  word  used  so  extensively  as  that 
which  led  to  the  language  above  quoted.     The  best  definition  which  I  can 
devise,  in  this  case,  is  that  a  salt  is  a  compound,  resulting  from  the  union 
of  at  least  two  acid,  acrid,  or  corrosive  ingredients ;  forming,  agreeably  to 
the  language  of  the  older  chemists,  a  tertium  quid,  or  in  plain  English,  a 
third  something,  differing  materially  from  its  constituents.     It  should,  as  I 
conceive,  be  crystallizable,  and  soluble  either  in  water  or  alcohol.     I  do 
not  think  that  a  satisfactory  line  of  demarcation  can  be  drawn  between 
salts,  acids,  and  bases.     Some  compounds  which  lean  so  much  towards 
salinity*  in  their  characteristics,  as  to  have  been  classed  with  salts,  have 
latterly  been  found  to  play  the  part  of  acids  or  bases,  as  instanced  by  the 
binary  halogen  salts.     I  would  consider  them  as  salts  when  acting  as  such, 
and  as  acids  or  bases  when  acting  as  acids  or  bases.     Berzelius  has  sug- 
gested this  kind  of  contingent  definition  in  the  instance  of  water  ;  which  he 
represents  as  acting  as  a  base  with  some  acids,  and  as  an  acid  with  some 
bases.     Thus  it  seems  possible  for  the  same  body  to  act  either  as  an  acid, 
a  salt,  or  a  base,  accordingly  as  it  may  be  associated. 

Of  the  Principal  Groups  of  Salts. 

2006.  As  respects  composition,  I  conceive  that  there 
are  at  least  three  groups  of  salts. 

2007.  1st.  Binary  saline  compounds  of  a  halogen  ele- 
ment and  a  metal. 

2008.  2d.  Saline  compounds  of  acids  and  bases,  tertium 
quids  agreeably  to  the  definition  of  acidity  and  basidity. 
(631.) 

2009.  3d.  Saline  compounds  containing  either  an  or- 
ganic acid  or  an  organic  base;  or  consisting  of  such  an 
acid,  united  with  such  a  base. 

*  I  am  unable  to  refer  to  any  authority  for  the  use  of  this  word,  but  conceive 
myself  justified  in  employing  it,  as,  by  analogy,  it  cannot  be  misunderstood  by  the 
reader. 


OXYSALTS.  359 

2010.  As  far  as  consistent  with  the  due  allotment  of 
time,  I  have  given  ah  account  of  the  first  group  in  treat- 
ing of  the  metals.     But  the  class  thus  constituted  are 
capable  of  combining  with  each  other,  and  with  the  electro- 
negative or  acid  compounds,  formed  by  the  union  of  their 
halogen  ingredients  'with  non-metallic  radicals.     In  this 
way  compounds  are  produced,  which  Berzelius  designates 
as  double  haloid  salts.     I,  however,  consider  them  as  much 
entitled  to  be  treated  as  saline  compounds  of  acids  and 
bases,   as  the  double   sulphides,   selenides,  or  tellurides, 
which  are  so  treated  by  that  distinguished  chemist.  (627.) 

2011.  I  shall  designate  the  salts  comprised  in  the  1st 
and  2d  groups  abovementioned  by  their  basacigen  ingredi- 
ents. (633.)     Hence  the  nine  following  classes ;  oxysalts, 
sulphosalts,    selenisalts,    tellurisalts,    chlorosalts,   bromosalts, 
iodosalts,  fluosalts,  and  cyanosalts.     Obviously,  of  these  the 
first  four  are  formed  by  the  amphigen  bodies,  and  the  rest 
by  the  halogen  bodies  of  Berzelius. 

SECTION  I. 

OF    OXYSALTS. 

2012.  In  describing  the  oxysalts,  I  shall  be  constrained 
to  confine  my  remarks  to  some  of  the  more  important 
characteristics  of  each  of  the  sets  of  salts  formed  by  the 
different  inorganic  oxacids  with  the  more  energetic  bases. 
Some  of  those  formed  by  acids  of  minor  importance  will 
be  omitted  altogether. 

Of  Chlorates  and  Hypochlorites. 

2013.  As  agreeably  to  the  premised  arrangement,  the 
oxacids,  first  made  the  objects  of  attention  in  this  work, 
were  those  formed  by  the  union  of  chlorine  with  oxygen ; 
it  follows  that  the  saline  combinations  formed  by  those 
acids  with  bases,   should  be  the   first  to  be  treated  of 
among  oxysalts. 

2014.  We  have  four  acids  consisting  of  the  two  ele- 
ments abovementioned,   and,   consequently,  should  have 
four  species  of  salts,  hypochlorites,  chlorites,  chlorates, 
and    perchlorates,  or  oxychlorates.     It  seems,  however, 
doubtful  whether  chlorous  acid  can  be  presented  to  a  base, 
without  being  resolved  into  a  chlorate  and  chlorine.     In 
this  respect,  it  seems  to  rest  on  the  same  footing  as  ni- 


360  INORGANIC  CHEMISTRY. 

trous  acid.  (984,  2004.)     Of  course  there  are  no  chlo- 
rites. 

2015.  The  chlorates  and  hypochlorates  are  the  products 
of  one  process,  in  which  an  oxybase  is  made  to  react  with 
chlorine.     In  the  process  alluded  to,  a  fixed  alkali,  or  any 
of  the  three  more  powerful  alkaline  earths,  whether  in  solu- 
tion, in  a  state  of  suspension,  or  in  the  pulverulent  state 
of  a  hydrate,  being  sufficiently  exposed  to  chlorine,  is  found 
to  acquire  the  bleaching  and  disinfecting  properties  with 
which  that  gas  is  so  remarkably  endowed. 

2016.  In  the  case  in  which  a  solution  of  potassa  is 
saturated  with  the  gas,  besides  the  acquisition  of  bleaching 
power,  by  the  mother  water,  crystals  result  of  chlorate  of 
potash,  which  from  their  inferior  solubility  precipitate. 

2017.  This  process  was  rather  an  empyrical  improve- 
ment, when   first   employed;    because,  agreeably  to   the 
science  of  the  day,  nothing  could  have  been  less  likely  to 
succeed.     At  that  time,  chlorine  was  considered  as  an 
oxacid  of  an  unknown  radical.  (886.)     But  if  the  bleach- 
ing and  disinfecting  properties  of  chlorine  were  due  to 
acidity,  nothing  could  be  less  consistent  with  the  retention 
of  those  properties,  than  saturation  with  powerful  bases. 
Subsequently,  when  the  elementary  character  of  chlorine 
became  known,  the  ascertained  retention  of  its  bleaching 
and  disinfecting  power,  after  combination  with  an  oxy- 
base, appeared  much  more  consistent  with  the  supposed 
nature  of  the  ingredients. 

2018.  It  was  conceived,  that  chlorine  feebly  attracted 
to  an  oxybase,  was  liberated  by  its  affinity  for  colouring- 
matter,  or  feculent  emanations,  or  by  the  affinity  of  any 
other  principle  for  the  oxybase.    Accordingly,  until  within 
the  last  ten  years,  the  impression  generally  prevailed,  that 
the  liquids,  powders,  or  salts  employed  in  bleaching,  were 
compounds   of  an   oxybase  with   chlorine.      Hence,   the 
terms  chloride  of  lime,  or  chloride  of  potassa,  or  of  soda, 
which  are  still  in  use,  especially  among  manufacturing 
chemists.    • 

2019.  It  was  in  the  treatise  of  Berzelius,  that  I  first  met 
with  the  explanation  which  I  gave  in  the-  last  edition  of 
this  text  book,  of  the  process  under  consideration,  and 
which  I  now  subjoin. 

2020.  When  into  a  solution  of  potash,  (oxide  of  potas- 
sium,) chlorine  is  introduced,  one  portion  of  it  combines 


OXYSALTS.  361 

with  the  potassium,  separating  from  each  atom  the  atom 
of  oxygen  by  which  it  was  oxidized.  The  oxygen  thus 
liberated  from  several  atoms  of  the  metal,  coming  into 
contact  with  another  portion  of  chlorine,  forms  with  it 
chlorous  acid.  Each  atom  of  the  acid,  thus  formed,  unites 
with  an  atom  of  potash,  producing  a  chlorite.  By  con- 
tinuing the  operation  until  all  the  potash  which  remains 
free  is  decomposed,  that  which  has  meanwhile  united  with 
the  acid  is  attacked  by  the  chlorine,  and  the  oxygen,  libe- 
rated in  consequence  from  each  atom  of  the  chlorite,  con- 
verts another  portion  of  this  salt  into  a  chlorate.  This 
salt  being  inferior  in  solubility  to  the  chloride,  precipitates 
in  crystals,  which  being  subjected  to  boiling  water,  are 
purified  by  the  recrystallization  which  cooling  induces. 

2021.  This  explanation  seems  to  require  modification, 
only  so  far  as  to  introduce  the  hypochlorous  in  lieu  of  the 
chlorous  acid,  (688,)  agreeably  to  the  new  view  of  the 
subject  presented  in  treating  of  the  compounds  of  chlorine 
with  oxygen.    Reference  is  there  made  to  the  investiga- 
tions of  Balard,  by  which  it  has  been  shown  that  the  gase- 
ous product  supposed  to   be  the  protoxide  of  chlorine, 
called  euchlorine  by  Davy,  is  really  a  mixture  of  chlorous 
acid  with  chlorine;  and  also  that  the  real  protoxide  of 
chlorine,  is  the  acid  which  is  formed  during  the  process 
for  making  chlorate  of  potash,  or  bleaching  powders,  and 
which  is  now  designated  as  hypochlorous  acid. 

2022.  The  impure  hypochlorite  of  lime,  called  bleach- 
ing salt,  is  obtained  by  exposing  hydrate  of  lime  to  chlo- 
rine.   Analogous  salts  of  potash  and  soda  are  found  in  the 
mother  waters  of  the  chlorates  of  those  alkalies,  and  may 
likewise  be  obtained,  by  double  decomposition,  from  the 
hypochlorite  of  lime;  and  carbonate  of  potash  or  soda. 
When  obtained  by  these  methods,  hypochlorites  are  min- 
gled with   the  chlorides  of  the  metals  peculiar  to  their 
respective  bases. 

2023.  Properties. — The    hypochlorites    are    extremely 
susceptible  of  decomposition.     This,  however,  takes  place 
in  a  manner  which  varies  with  the  circumstances  in  which 
they  are  placecl.     Bleaching  or  disinfection  is  effected  by 
them  when  quite  pure,  by  imparting  oxygen;   being  re- 
solved into  this  element  and  a  chloride.     Chlorine  pro- 
duces similar  effects,  by  causing  water  to  impart  oxygen. 
No  doubt  the  result  is  the  consequence  of  complex  affinity, 

46 


362  INORGANIC    CHEMISTRY. 

the  hydrogen  being  attracted  by  the  chlorine,  the  oxygen 
by  some  oxidizable  substance. 

2024.  When  carbonic  acid  has  access  to  an  hypochlo- 
rite,  it  combines  with  the  base  of  the  salt,  displacing  the 
acid;  and  if  a  chloride  be  present,  its  radical  is  oxidized 
by  the  oxygen  of  the  acid  thus  displaced;  while  its  chlo- 
rine is  liberated,  as  well  as  that  of  the  chlorous  acid.     Of 
course   an   evolution   of  chlorine   must   ensue  from   the 
employment,  in  like  case,  of  any  acid,  which,  in  its  affini- 
ties, is  not  less  energetic  than  carbonic  acid.    If,  however, 
a  pure  hypochlorite,  formed  by  the  action  of  hypochlorous 
acid  on  a  base,  be  subjected  to  the  action  of  a  more 
powerful  acid,  the  hypochlorous  acid  may  be  liberated 
without  being  decomposed. 

2025.  When  an  aqueous  solution  of  a  hypochlorite  is 
boiled  in  pure  water,  one  portion  of  the  chlorite  is  con- 
verted into  a  chloride;  while  the  oxygen,  which  is  libe- 
rated from  it  during  this  transformation,  converts  another 
portion  into  a  chlorate. 

2026.  According  to  Thomson,  when  chloride  of  am- 
monium is  introduced  into  a  retort  containing  the  hypo- 
chlorite of  lime  of  commerce,   made  into  a  paste  with 
water,  gaseous  nitrogen  is  evolved  with  a  reaction  so  vio- 
lent, that,  in  order  to  delay  the  extrication  until  his  ar- 
rangements for  collecting  the  product  were  completed,  he 
found  it  expedient  to  wrap  the  hypochlorite  in  blotting 
paper. 

Experimental  Illustrations. 

2027.  Production  of  hypochlorite  of  lime.     Its  effects 
upon  colouring  matter.     Evolution  of  nitrogen  from  chlo- 
ride of  ammonium,  by  hypochlorite  of  lime. 

Properties  of  the  Chlorate. 

2028.  The  chlorates  resemble  the  nitrates  in  deflagrat- 
ing with  combustibles ;  but  the  residuum  which  they  leave 
is  always  a  chloride;  and  the  deflagration  is  more  power- 
ful and  more  easily  effected.     If  chlorate  of  potash  be 
triturated  in  contact  with  sulphur  or  phosphorus,  an  ex- 
plosion ensues.     Salts  of  this  class  give  up  their  oxygen, 
and  are  converted  into  chlorides,  simply  by  being  heated. 
They  are  almost  all  soluble  in  water.    The  chlorate  of  the 
protoxide  of  mercury  is  said  to  be  but  sparingly  soluble. 


OXYSALTS.  363 

2029.  The  properties  of  the  chlorates  are  most  con- 
veniently illustrated  by  the  chlorate  of  potash,  which  is  an 
efficient  material  in  several  varieties  of  the  matches  which 
are  ignited  either  by  contact  with  sulphuric  acid,  by  fric- 
tion, or  crushing. 

2030.  Alcohol,  or  any  of  the  essential  oils,  oil  of  turpen- 
tine for  instance,  may  be  ignited  by  means  of  chlorate  of 
potash  and  sulphuric  acid. 

Experimental  Illustrations* 

2031.  Ignition  of  phosphorus  with  chlorate  of  potash 
by  percussion.     Explosion  of  sulphur  mixed  with  the  chlo- 
rate, by  trituration.  Composition  for  friction  matches  con- 
sisting of  chlorate  of  potash,  sulphur,  and  phosphorus, 
mingled  with  gum,  exhibited  and  ignited.     About  as  much 
chlorate  of  potash  as  may  be  piled  upon  a  half  cent,  being 
deposited  in  a  heap  amid  the  inflammable  liquid,  the  af- 
fusion of  concentrated  sulphuric  acid  upon  the  heap,  causes 
the  liquid  to  be  inflamed. 


Combustion  of  Phosphorus  under  Water,  by  means  of 
Chlorate  of  Potash  and  Sulphuric  Add. 

2032.  Let  there   be   two   tubes,   one   within  the 
other,  as  here  represented ;  the  larger  one,  closed  at 
the  lower  end,  and  containing  water;  the  other  open 
at  both  ends,  the  upper  orifice  funnel-shaped,  and 
the  bore  about  one-twelfth  of  an  inch  in  diameter. 
Allow  some  very  small  pieces  of  phosphorus,  and  a 
few  crystals  of  chlorate  of  potash,  to  fall  down  to  the 
bottom  of  the  large  tube.     Then,  into  the  smaller 
tube,    pour  some  sulphuric  acid ;    so  that,  without 
being  much  diluted,  it  may  descend  upon  the  chlo- 
rate and  phosphorus.     A  vivid  ignition  ensues,  in 
despite  of  the  surrounding  water. 

2033.  The  sulphuric  acid,  uniting  with  the  potash 
of  the  chlorate,  liberates  chlorine  and  oxygen,  which, 
coming  into  contact  with  the  phosphorus,  cause  its 
combustion. 


364  INORGANIC  CHEMISTRY. 

Of  Perch/orates  or  Oxy chlorates. 

2034.  One  of  the  processes  for  procuring  oxychlorate  of 
potash,  has  been  mentioned  in  the  text,  while  treating  of 
oxychloric  acid,  (712,)  and  another  is  mentioned  in  a  note. 
Oxychlorates  of  other  bases,  are  obtained  either  by  double 
decomposition  ;  or  by  the  direct  union  of  the  acid,  made 
as  already  suggested.  (713.) 

2035.  The  oxychlorates,  in  general  properties,  resemble 
the  chlorates.     They  appear,  however,  to  be  less  suscepti- 
ble of  decomposition;  since  the  oxychlorate  of  potash  is 
not  decomposed  by  any  of  the  acids  at  ordinary  tempera- 
tures, and  does  not  react  as  violently  with  sulphur  as  the 
chlorate  of  potash. 

2036.  Nearly  all  of  the  oxychlorates  would  appear  to 
be  deliquescent,  and  soluble  in  alcohol,  excepting  those  of 
potash,  lead,  protoxide  of  mercury,  and   ammonia.      At 
the  temperature  of  59°,  oxychlorate  of  potash  requires  for 
its  solution  sixty-five  times  its  weight  of  water. 

OF  NITRATES. 

2037.  This  class  of  salts  is  distinguished  by  deflagrating 
with  charcoal  and  other  combustibles.     When  the  com- 
bustible is  susceptible  of  acidification,  the  resulting  acid 
unites  always  with  the  base.     Thus  in  the  case  of  char- 
coal, a  carbonate  is  left ;  in  the  case  of  silicon,  a  silicate ; 
in  the  case  of  sulphur,  a  sulphate ;  in  the  case  of  arsenic, 
an  arseniate.     They  differ  from  the  oxysalts  containing 
an  acid  with  a  halogen  radical  (the  chlorates  for  instance,) 
in  leaving  an  oxide  after  deflagration,  instead  of  a  haloid 
salt.     Thus  the  nitrate  of  potash  leaves  the  oxide  of  potas- 
sium ;  while  the  chlorate  leaves  a  chloride  of  potassium. 

2038.  If  subjected  to  concentrated  sulphuric  acid,  the 
nitrates,  when   dry,   emit  fumes  of  nitric   acid.     When 
added  to  liquid  chlorohydric  acid,  by  dehydrogenating  the 
chlorine,  they  enable  it  to  act  on  gold  leaf,  as  it  does  when 
presented  to  this  metal  in  aqua  regia. 

2039.  The  neutral  nitrates  are  all  soluble,  and  many  of 
them  deliquescent. 

Experimental  Illustrations' 

2040.  Deflagration  of  a  nitrate  upon  ignited  charcoal, 
of  charcoal  and  other  substances  upon  fused  nitrate  of 


NITRITES  AND  HYPONITRITES. SULPHATES.  365 

potash,  soda,  copper,  or  strontia.  A  nitrate  added  to 
liquid  chlorohydric  acid  containing  gold  leaf,  causes  the 
solution  of  the  metal.  Decomposition  of  a  nitrate  by 
heat. 

OF  NITRITES  AND  HYPONITRITES. 

2041.  It  would  appear  that  the  compound,  which,  con- 
sistently with  the  practice  of  the  British  and  French  chem- 
ists, has  been  designated  as  nitrous  acid,  is  decomposed 
when  presented  to  bases,  forming  a  nitrate  and  hyponitrite. 
It  is.  probable,  therefore,  that  there  are  no  salts  which 
properly  deserve  the  name  of  nitrites,  in  the  sense  in  which 
this  appellation  has  been  used  by  the  chemists  abovemen- 
tioned.     It  has  already  been  stated  that  Berzelius  does  not 
admit  the  existence  of  any  acid  intermediate,  as  respects 
the  quantity  of  oxygen  contained,  between  nitric  and  hy- 
ponitrous  acid,  and,  therefore,  calls  the  acid  to  which  the 
last  mentioned  name  has  been  applied,  nitrous  acid,  and 
of  course   designates  its  compounds   as  nitrites.  (984.) 
The  hyponitrites  of  the  English  and  French  chemists,  or 
nitrites  of  Berzelius,  resemble  the  nitrates  in  most  of  their 
properties ;    but  may  be  recognised  by  the  red  vapours 
which  they  evolve  on  the  addition  of  any  of  the  stronger 
acids.  (981,  &c.) 

OF  SULPHATES. 

2042.  Their  solutions  all  yield  precipitates  with  solutions 
of  baryta.     Heated  in  contact  with  charcoal  or  hydrogen, 
they  are  converted  into  sulphurets,  which,  if  moistened, 
smell  like  rotten  eggs.     They  are  almost  all  insoluble  in 
alcohol.     The  sulphates  of  baryta,  tin,  antimony,  bismuth, 
and  lead,  are  quite  insoluble  in  water.     Those  of  strontia, 
lime,  yttria,  mercury,  silver,   and  the  sesquioxide  of  ce- 
rium, are  nearly  insoluble;  while  all  other  sulphates  are 
soluble. 

Experimental  Illustrations. 

2043.  Precipitation  of  sulphates  by  solutions  of  baryta. 
Conversion  of  a  sulphate  into  a  sulphuret  before  the  blow- 
pipe, demonstrated  by  the  subsequent  effect  upon  a  metal- 
lic solution. 


366  INORGANIC  CHEMISTRY. 


OF  HYPOSULPHATES,  SULPHITES,  AND  HYPOSULPHITES. 

2044.  The  hyposulphate  of  baryta,  is  obtained  by  adding  sulphide  of 
barium  to  a  solution  of  hyposulphate  of  manganese.  (764.)     The  hypo- 
sulphates  of  lime  and  strontia  are  procured  in  the  same  manner,  and  the 
hyposulphates  of  the  other  bases,  either  by  double  decomposition,  or  by 
adding  the  acid  directly  to  the  base. 

2045.  The  neutral  hyposulphates  are  probably  all  soluble.     This  pro- 
perty, together  with  their  conversion  into  sulphates  by  heat,  and  the  odour 
of  sulphurous  acid  which  they  emit  on  the  addition  of  concentrated  sul- 
phuric acid,  is  sufficient  to  enable  us  to  recognise  them. 

2046.  The  insoluble  sulphites  are  obtained  by  double  decomposition; 
those  which  are  soluble,  by  the  direct  action  of  the  acid  on  the  base. 

2047.  The  sulphites  are  generally  insoluble,  and  may  be  recognised  by 
the  odour  of  sulphurous  acid  which  they  emit  on  the  addition  of  diluted 
sulphuric  acid ;  while  they  do  not,  like  the  hyposulphites,  simultaneously 
deposite  sulphur:  also  by  their  not  yielding,  like  the  hyposulphates,  a  neu- 
tral sulphate  by  heat. 

2048.  The  hyposulphites  are  procured  by  treating  metallic  zinc,  iron,  or 
manganese,  with  liquid  sulphurous  acid.     Each  atom  of  this  acid  abandons 
one  atom  of  oxygen  to  the  metal,  being  consequently  converted  into  hypo- 
sulphurous  acid,  which,  with  the  resulting  oxide,  forms  a  hyposulphite. 

2049.  The  hyposulphites  may  likewise  be  formed  by  boiling  sulphites 
with  flowers  of  sulphur,  by  which  each  atom  of  acid  in  any  sulphite  takes 
up  an  additional  atom  of  sulphur,  converting  the  sulphite  into  a  hyposul- 
phite. 

2050.  The  hyposulphites  may  all  be  decomposed  by  heat,  and,  when 
acted  on  by  sulphuric  acid,  deposite  sulphur  and  liberate  sulphurous  acid. 

OF  SELENIATES. 

2051.  The  seleniates  greatly  resemble  the  sulphates  in  properties.   They 
are  in  fact  isomorphous  with  them,  and  crystallize  with  the  same  quantity 
of  water  of  crystallization.     The  seleniates  are,  however,  more  susceptible 
of  decomposition  than  the  sulphates,  and  when  thrown  on  burning  coals 
deflagrate. 

OF  PHOSPHITES. 

2052.  The  phosphites  are  obtained  either  by  presenting  the  acid  directly 
to  the  base,  or  by  double  decomposition.     When  thrown  on  burning  coals 
they  produce  a  yellow  flame,  the  colour  of  which  increases  in  intensity 
with  the  quantity  of  acid  contained  in  the  salt. 

OF  PHOSPHATES. 

2053.  The  phosphates  all  give  precipitates  with  solutions 
of  baryta,  lime,  lead,  and  silver. 

2054.  The  phosphates  are  not  decomposable  by  heat 
alone.     Those  of  the  metals  proper  may  be  converted,  by 
heat  and  charcoal,  into  phosphurets  of  the  metals  peculiar 
to  their  respective  bases.     In  the  case  of  the  phosphates 
of  the  earths  and  alkalies,  a  portion  of  the  phosphoric  acid 


CARBONATES. BORATES. SILICATES.  367 

is  deoxidized  by  the  carbon,  evolving  phosphorus;  while 
the  remainder  forms  with  the  base  a  subphosphate. 

2055.  By  heat  the  phosphates  are  converted  into  para- 
phosphates,  identical  in  composition,  though  different  in 
properties. 

2056.  According  to  Thenard,  phosphoric  acid  combines 
with  bases  in  five  different  proportions,  forming  biphos- 
phates,  sesquiphosphates,  neutral  phosphates,  sesquibasic  phos- 
phates, and  bibasic  phosphates,  in  which  the  equivalents  of 
acid  to  those  of  the  base  are  respectively  as  2  to  1,  II  to  1, 
1  to  1,  1  to  li,  and  1  to  2. 

OF  CARBONATES. 

2057.  This  class  of  salts  is  distinguished  by  being  sus- 
ceptible of  decomposition,  with  effervescence,  by  any  of 
the  acids,  excepting  a  few  that  are  remarkably  feeble,  as, 
for  instance,  the  cyanhydric  and  meconic  acids. 

2058.  All  the  alkaline  carbonates  are  decomposable  by 
heat,  excepting  those  of  potassa,  soda,  baryta,  strontia,  and 
probably  hthia. 

2059.  Each  of  the  alkalies,  potash,  soda,  and  ammonia, 
forms  with  carbonic  acid,  a  carbonate,  consisting  of  an 
equivalent  proportion  of  each  ingredient;  a  sesquicarbon- 
ate,  in  which  there  are  one  equivalent  and  a  half  of  acid 
to  one  of  alkali;  and  a  bicarbonate,  in  which  there  are 
two  equivalents  of  the  acid  to  one  of  alkali.     When  satu- 
rated with  the  acid,  they  are  more  susceptible  of  crystal- 
lization, and  less  nauseous  to  the  taste. 

2060.  The  evolution  of  the  acid  from  the  carbonates  of 
lime  and  ammonia  has  been  already  exhibited. 

OF  BORATES. 

2061.  The  biborate  of  soda  is  found  in  nature  in  certain  lakes,  and  is 
known  in  commerce  as  borax.     In  the  examination  of  minerals  by  the 
blowpipe,  it  is  very  useful. 

2062.  The  other  soluble  borates,  which  are  those  of  potash,  soda,  lithia, 
and  ammonia,  are  obtained  by  uniting  the  acid  directly  with  the  base.  The 
borates,  which  are  quite  or  nearly  insoluble,  are  procured  by  double  de- 
composition with  the  borate  of  soda.     Borates  are  undecomposable  by  heat, 
when  their  bases  are  undecomposable  by  that  agent.     Other  borates,  when 
intensely  heated,  are  resolved  into  oxygen,  a  metallic  radical,  and  boric 
acid. 

OF  SILICATES. 

2063.  The  silicates  are  procured  either  by  double  decomposition,  or  by 
heating  silicic  acid  strongly  with  the  base.     They  are  not  decomposable  by 


368  INORGANIC  CHEMISTRY. 

heat  alone;  although,  when  heated  with  charcoal,  some  of  the  silicates  are 
converted  into  silicurets.  All  the  silicates,  excepting  those  of  potash,  soda, 
and  lithia,  are  insoluble. 

OF  CYANATES  AND  FULMINATES. 

2064.  The  soluble  cyanates  are  decomposable  by  water,  and,  if  insolu- 
ble, by  acids,  into  carbonic  acid  and  ammonia.    The  fulminates  are  chiefly 
remarkable  for  the  violent  explosions  which  they  produce  by  heat  or  per- 
cussion.    The  fulminate  of  mercury  is  employed  as  priming  in  percussion 
gun  locks.     It  may  be  obtained  by  the  following  process :  Dissolve  100 
grains  of  mercury  with  heat  in  a  measured  ounce  and  a  half  of  nitric  acid 
of  moderate  strength ;  when  cold,  mix  the  solution  with  a  measured  ounce 
and  a  half  of  alcohol,  and  apply  heat  till  effervescence  takes  place.    When 
red  fumes  appear,  check  the  action  with  water.     The  powder  which  preci- 
pitates, well  washed  with  water,  and  afterwards  dried  at  a  gentle  heat,  will 
be  the  fulminate  of  mercury. 

OF  DOUBLE  OXYSALTS. 

2065.  There  are  many  cases  in  which  two  salts,  formed  by  different 
bases  but  of  the  same  acid,  enter  into  combination.     A  compound  thus  con- 
stituted, formerly  received  the  appellation  of  a  triple  salt,  but  is  now  desig- 
nated as  a  double  salt. 

2066.  Tartar  emetic  is  a  double  tartrate,  consisting  of  tartrate  of  potash 
combined  with  tartrate  of  antimony.   (1919.) 

2067.  Rochelle  salt  is  a  compound  of  tartrate  of  potash  with  the  tartrate 
of  soda.     An  analogous  compound  is  formed  by  the  union  of  tartrate  of  pot- 
ash with  tartrate  of  iron,  called  ferri  et  potassce  tartras,  or  tartrate  of 
potash  arid  iron,  in  the  United  States'  Dispensatory ;  to  which  I  refer  stu- 
dents for  much  valuable  information  which  my  limits  will  not  allow  me  to 
add. 

2068.  The  saline  compound,  well  known  under  the  name  of  alum,  is 
composed  of  one  atom  of  trisulphate  of  alumina,  and  one  of  sulphate  of  pot- 
ash, besides  twenty-four  atoms  of  water  of  crystallization. 

2069.  Other  double  sulphates  have  been  formed  analogous  to  alum,  sub- 
stituting soda  or  ammonia  for  potash,  or  iron,  manganese,  or  chromium  for 
alumina. 

2070.  Double  silicates  and  carbonates  exist  in  nature.     Dolomite  is  a 
species  of  marble,"  consisting  of  the  carbonates  of  lime  and  magnesia  in 
equivalent  proportions.     Felspar  consists  of  a  silicate  of  alumina  and  a  sili- 
cate of  potash.     Many  native  crystals,  well  known  to  mineralogists,  are 
double  silicates. 

2071.  Glass,  in  general,  is  a  combination  of  one  or  more  silicates.    Flint 
glass,  according  to  Turner,  is  a  double  sexsilicate  of  lead  and  potash. 

2072.  It  ought  not  to  be  supposed  that  double  salts  are  always  produced 
by  the  combination  of  single  salts  previously  existing  separately.     In  the 
case  of  tartar  emetic,  the  bitartrate  of  potash,  containing  two  equivalents  of 
acid  to  one  of  base,  is  converted  into  the  double  tartrate  of  potash  and  anti- 
mony, by  saturating  with  one  equivalent  of  the  sesquioxide  of  this  metal, 
one  equivalent  of  the  acid  in  the  bitartrate.     Thus  a  tartrate  of  antimony  is 
produced  in  combination  with  a  tartrate  of  potash,  and  a  double  salt  is  of 
course  formed. 

2073.  It  appears  possible  for  two  double  salts  to  combine,  as  when  bibo- 


SULPHOSALTS. SELENISALTS  AND  TELLURISALTS.        369 

rate  of  soda  (borax)  is  added  to  bitartrate  of  potash,  in  order  to  produce 
the  "  soluble  cream  of  tartar"  of  pharmacy.  According  to  Berzelius,  this 
compound  may  be  considered  as  consisting  of  a  double  tartrate  of  potash 
and  soda  (sal  Rochelle),  combined  with  a  double  tartrate  of  potash,  and 
boric  acid  acting  as  a  base.  See  United  States'  Dispensatory. 


SECTION  II. 

OF   SULPHOSALTS. 

2074.  Berzelius  alleges  that  the  metallic  sulphides,  which  are  capable 
of  combining  with  each  other  to  form  sulphosalts,  contain  for  each  atom  of 
radical,  the  same  number  of  atoms  of  sulphur,  as  the  salifiable  oxybases 
and  oxacids  of  the  same  radicals  contain  of  oxygen.     In  consequence  of 
this  analogy  in  composition,  if  sulphydric  acid  gas  be  transmitted  through 
a  concentrated  solution  of  an  oxysalt,  in  which  the  acid  and  base  have 
each  a  metallic  radical,  the  hydrogen  of  the  sulphydric  acid  takes  all  the 
oxygen  from  both  radicals.     Meanwhile,  an  equivalent  number  of  atoms 
of  sulphur,  consequently  liberated,  take  the  place  of  the  oxygen,  forming  a 
sulphosalt,  consisting  of  a  sulphacid  and  a  sulphobase,  analogous,  in  the 
number  of  atoms  of  each  ingredient,  to  the  oxysalt,  from  the  decomposi- 
tion of  which  it  originates. 

2075.  In  order,  however,  to  effect  the  combination  of  the  electro-positive 
metallic  sulphides  which  act  as  bases,  with  the  sulphides  of  non-metallic 
radicals  which  act  as  sulphacids,  a  different  method  must  be  adopted.     In 
the  case  of  sulphydric  acid  gas,  which  does  not  combine,  except  with  the 
sulphides  of  the  metals  of  the  alkaline  earths  and  alkalies,  it  is  either 
brought  into  contact  with  a  carbonate  of  the  base  heated  to  redness,  or 
else  made  to  enter  into  a  solution  of  the  hydrate.     Whichever  method  be 
adopted,  no  access  of  atmospheric  oxygen  should  be  allowed.     In  either 
case,  one  portion  of  the  sulphydric  acid  is  decomposed,  its  hydrogen  com- 
bining with  the  oxygen  of  the  base,  and  its  sulphur  with  the  metal  ;  while 
the  other  portion  of  the  acid  unites  with  the  sulphide  thus  formed,  pro- 
ducing a  sulphydrate. 

2076.  It  has  been  stated,  (1248,)  that  combinations  of  sulphocarbonic 
acid  may  be  formed  with  most  of  the  electro-positive  sulphides,  either  by 
direct  union,  or  by  double  decomposition.    There  are  other  methods  of  pre- 
paring these  sulphosalts,  of  which  I  cannot  treat,  consistently  with  the 
limits  prescribed  for  this  work. 


SECTION  III. 

OF  SELENISALTS  AND  TELLURISALTS. 

2077.  As  has  been  already  stated,  both  selenium  and  tellurium  are 
capable  of  combining  with  different  radicals,  forming  selenides  and  tellu- 
rides.  These,  in  many  cases,  like  the  corresponding  compounds  formed  by 
sulphur,  unite  together  to  form  selenisalts  and  tellurisalts.  The  resulting 
combinations,  however,  have  been  but  little  studied. 
47 


370  INORGANIC  CHEMISTRY. 


SECTION   IV. 

OF  CHLOROSALTS,  BROMOSALTS,  IODOSALTS,  AND 
FLUOSALTS  OF  THE  SECOND  GROUP. 

2078.  The  chlorosalts  are  generally  obtained  by  mingling  chloracids 
with  chlorobases  (631),  either  in  the  wet  or  dry  way.     In  the  latter  case, 
heat  must  be  employed  in  order  to  facilitate  their  union. 

2079.  The  bromosalts  and  iodosalts  may  in  general  be  obtained  in  the 
same  manner,  by  mingling;bromacids  with  bromobases,  or  iodacids  with 
iodobases. 

2080.  I  have  mentioned,  in  treating  of  the  chlorides  of  the  metals,  seve- 
ral instances  in  which  combinations  are  formed  by  them  with  chlorohydric 
acid.     Such  compounds,  however,  are  rare,  and,  when  they  do  occur,  ap- 
pear not  to  possess  stability. 

2081.  I  have  stated  (1396,)  my  opinion  that  the  compounds,  designated 
by  Berzelius  as  fluohydroboric  acid  and  fluohydrosilicic  acid,  should  be 
considered  as  tertium  quids,  in  which  the  fluoride  of  hydrogen  performs 
the  part  of  a  base,  while  the  fluorides  of  boron  and  silicon  act  as  acids. 
Hence  fluohydroboric  acid  is  a  fluoborate  of  hydrogen,  and  fluohydrosilicic 
acid,  a  fluosilicate  of  hydrogen. 

2082.  With  the  fluorides  of  columbium  and  titanium,  the  fluoride  of 
hydrogen  forms  compounds  analogous  to  those  abovementioned,  and  which 
I  would  designate  as  fluocolumbate,  and  fluotitaniate  of  hydrogen. 

2083.  When  any  fluosalt  like  those  abovementioned,  in  which  hydrogen 
exists  as  a  radical,  is  brought  into  contact  with  an  oxybase,  of  which  the 
radical  is  capable  of  forming  a  fluobase,  the  hydrogen  unites  with  the  oxy- 
gen of  the  oxybase,  while  the  radical  of  this  base  unites  with  the  fluorine. 
The  fluacid  of  the  fluosalt,  consequently  liberated,  combines  with  the  re- 
sulting fluobase. 

2084.  The  other  fluosalts  are  formed  by  the  direct  reaction  of  the  fluacids 
and  fluobases  which  compose  them,  either  in  the  wet  or  dry  way.    By  add- 
ing fluohydric  acid  to  the  fluorides  of  potassium  and  sodium,  fluohydrates 
of  those  fluobases  may  be  formed.  (1398.) 


SECTION  V. 

OF   CYANOSALTS. 

2085.  The  cyahosalts  are  in  general  obtained  either  by  the  direct  union 
of  a  cyanacid  with  a  cyanobase,  or  by  decomposition.  It  is  by  the  latter 
method  that  the  cyanoferrite  of  potassium  is  formed,  the  sulphate  of  the 
protoxide  of  iron  being  presented  to  the  cyanide  of  potassium.  In  this  case 
the  sulphuric  acid,  and  the  oxygen  of  the  protoxide  of  iron,  are  transferred 
to  one  portion  of  the  potassium.  The  cyanogen,  consequently  liberated, 
forms  with  the  iron,  cyanoferrous  acid,  which  unites  with  the  undecom- 
posed  portion  of  the  cyanide  of  potassium.  (1299.  &c.) 


COMPENDIUM 


THE  COURSE  OF  CHEMICAL  INSTRUCTION 


THE  MEDICAL  DEPARTMENT 


THE  UNIVERSITY  OF  PENNSYLVANIA. 

BY 

ROBERT    HARE,   M.D. 

PROFESSOR  OF  CHEMISTRY. 

PART  II. 

COMPRISING     THE 

CHEMISTRY  OF  ORGANIC  SUBSTANCES;  BEING  A  COMPENDIOUS  SELEC- 
TION FROM  THE  PREVIOUS  EDITION:  THE  "TREATISE  OF  ORGANIC 
CHEMISTRY,"  BY  LIEB1G:  GREGORY'S  TURNER:  KANE'S  "ELEMENTS," 
AND  THOSE  OF  GRAHAM:  INTERSPERSED  WITH  SOME  ORIGINAL 
MATTER. 

Also,  a  Letter  on  the  Berzelian  Nomenclature,  with  the  Reply  of  Berzelius ; 
with  some  Subsequent  Remarks  and  Suggestions  by  the  Author. 

And  an  Effort  to  Refute  the  Arguments  advanced  in  favour  of  the  Exist- 
ence of  Compound  Radicals,  like  Cyanogen,  in  the  Amphide  Salts. 


PHILADELPHIA: 

SOLD  BY  J.  G.  AUNER,  No.  333  MARKET  STREET, 

AND 

CAREY  &  HART,  CORNER  OF  FOURTH  AND  CHESNUT  STREET. 
John  C.  Clark,  Printer,  60  Dock  Street. 

1843. 


OF  ORGANIC  CHEMISTRY, 


OR 


THE  CHEMISTRY  OF  ORGANIC  SUBSTANCES. 


CONTENTS. 

Organic  substances  defined — Ultimate  elements — Of  organic  hydrates,  Prout's  opi- 
nion respecting — Influence  of  heat  upon  vegetables,  with  and  without  access  of 
air — Ultimate  analysis  of  organic  substances — Of  the  mode  in  which  their  ulti- 
mate elements  are  associated — Of  compound  radicals — Of  substitution, 

Page  373  to  379 

OF  COMPOUND  RADICALS. 

Of  amide — Carbonic  oxide — Benzule,  benzoile,  or  benzyl — Cinnamyl — Salicyl — 
Ethyl — Acetyl — Kacodyl — Mesityl,  or  misitylene — Methyl — Formyl — Amyl — 
Glyceryl— Cetyl,  -  -  Page  380  to  398 

OF  NUTRITIOUS  VEGETABLE  SUBSTANCES  DEVOID  OF  NITROGEN. 

Of  Gum — Sugars — Grape  sugar — Sugar  of  milk — Mushroom  sugar — Fermentable 
matter  of  diabetes — Liquorice  sugar — Manna  sugar,  -  Page  400  to  406 

Of  fecula,  or  starch — Of  diastaste,  and  of  the  conversion  of  fecula  into  dextrine  and 
grape  sugar— Lignin,  -  Page  406  to  409 

OF  VEGETO-ANIMAL  SUBSTANCES. 

Of  gluten — Vegetable  albumen — Gluten  and  albumen  of  wheat — Legumen,  or  ve- 
getable caseine,  -  Page  411  to  413 

Composition  of  vegetable  fibrin,  vegetable  albumen,  vegetable  caseine,  and  vegeta- 
ble gluten — Composition  of  animal  caseine,  Page  418  to  419 

OF  VEGETABLE  COLOURING  MATTER. 

Of  vegetable  colouring  matter,  or  dyes,  and  of  dyeing — Of  the  colouring  matter  of 
leaves  and  flowers,  Page  419  to  420 

OF  OILS. 
OF  FIXED  OILS. 

Of  stearine— Margarine — Olein— Saponification— Properties  of  the  fixed  oils, 

Page  424  to  426 

OF  VOLATILE  OILS. 

Of  the  resemblance  and  dissimilarities  of  the  fixed  and  volatile  oils — Volatile  oils  in 
particular — Volatile  oils  containing  sulphur  as  an  ultimate  element — Volatile 
oil  of  mustard— Volatile  oils  containing  oxygen — Volatile  oils  devoid  of  oxygen 
Of  oil  of  turpentine — Camphor — Artificial  camphor — Camphene,  or  camphelene, 
and  terebene — Kreosote — Essential  oils  which  are  hydrurets — Hydruret  of  ben- 
zule,  or  oil  of  bitter  almonds — Amiduret  of  benzule,  or  benzamide, 

Page  429  to  442 


IV  CONTENTS. 

OF  SUBSTANCES  MORE  OR  LESS  RESINOUS. 

Of  resins — Wax — Caoutchouc,  or  gum  elastic,  and  caoutchoucine — Balsams — Gum- 
resins — Opium — Bitumen,  petroleum,  naphtha,  amber,  and  mineral  coal, 

Page  442  to  452 

OF  ACIDS. 

'Of  acids  relatively  to  the  proportions  of  base  required  for  their  saturation — Formula 
for  monobasic  salts — Of  acetic  acid — Pyroligneous  acid — Acetates — Acetate  of 
ammonia,  or  spirit  of  mindererus — Lactic  acid — Citric  and  malic  acid — Tartaric 
acid,  and  paralartaric,  or  racemic  acid — Liquid  and  solid  pyrotartaric  acid — Gui- 
acine,  or  guaiacinic  acid — Tannic  acid — Artificial  tannin — Gallic  acid — Meconic 
acid — A  method  of  detecting  the  presence  of  opium — Acids  formed  from  sugar 
Formic  acid — Valerianic  acid — Caffeic  acid  and  caffee  tannic  acid — Acids  modi- 
fied by  an  union  with  organic  matter — Acids  modified  by  union  with  an  oxidized 
compound  radical — Sulphovinic  acid,  or  the  sulphate  of  ether,  and  water — Suc- 
cinic  acid — Benzoic  acid — Properties  of  benzoic  acid — Hippuric  acid — The  hip- 
purates — Formobenzulic  acid,  -  Page  453  to  478 

Of  salicylous  or  saliculous  acid,  also  called  the  hydruret  of  salicyl,  but  more  pro- 
perly considered  as  salicohydric  acid,  and  other  compounds  of  salicyl — Of  the 
acids  from  the  oil  of  gaultheria,  -  -  Page  479  to  482 

Saliculous  acid  with  bases — Saliculate  of  ammonia — Saliculimide — Saliculite  of  pot- 
ash; neutral— Saliculites  of  soda,  lime,  baryta,  and  magnesia— Basic  saliculite 
of  lead — Saliculite  of  silver — Melanic  acid — Saliculic  acid — Chlorosaliculic  acid 

Chlorosaliculimide Bromosaliculic  acid — lodosaliculic  acid Nitrosaliculic 

acid,  -  -  Page  480  to  482 

OF  URIL  AND  URIC  ACID. 

Of  uric  acid— Allantoin — Alloxan— Alloxanic  acid— Mesoxalic  acid— Mycomelinic 
acid — Parabanic  acid — Oxaluric  acid — Thionuric  acid — Uramilc — Uramilic  acid 
— Alloxantin — Products  of  the  decomposition  of  alloxantin — Murexide — Mu- 
rexan — On  the  influence  of  benzoic  acid  in  lessening  the  generation  of  uric  acid 
in  human  urine,  -  Page  484  to  492 

OF  ORGANIC  ALKALIES  OR  BASES. 

Table  of  the  organic  alkalies — Organic  alkalies  of  doubtful  existence—  Of  the  state 
in  which  the  organic  alkalies  exist  in  the  products  of  vegetation,  and  the  means 
of  extricating  them,  generally  described,  Page  493  to  496 

Of  morphia — Paramorphia — Codeia — Narcotina — Narcea — Quinia — On  the  reaction 
of  chlorine  with  quinia  and  its  salts — Of  cinchonia — Aricina — Strychnia — Bru- 
cia — Delphia — Veratria — Sabadilla — Jervina — Colchicina — Emetia — Solania — 
Caffein — Chelerythrina — Chelidonia — Atropia — Aconitia — B^lladonia — Datu- 
ria — Conina — Nicotina — Lobelina — Picrotoxine — Antiarine— Bases  from  the  oil 
of  mustard — Thiosinnamina — Sinnamina — Sinapolina — Cinchovine — Cisampe- 
lina — Hederina,  surinamina,  and  jamaicina,  Page  496  to  518 

Of  certain  general  characteristics  of  the  vegetable  alkalies,  distinguishing  them  from 
inorganic  bases,  and  of  those  which  distinguish  them  into  several  different  sets. 
Constitution  of  the  organic  alkalies,  Page  518  to  520 

OF  IMPORTANT  NEUTRAL  ORGANIC  PRINCIPLES. 

Ofsalicin,  a  neutral  principle,  and  of  some  compounds  derived  from  it,  or  to  the 
production  of  which  it  contributes — Saliretine — Chlorosalicine — Rutiline — Phlo- 
ridzine — Phloridzeine — Asparao-ine,  asparamide, altheine,  agedoile — Taraxacine, 

Page  521  to  524 

Of  certain  Vegetable  Principles  devoid  of  Nitrogen. 

Of  gentianine — Santonine — Picrolichenine — Cetrarine — Elaterine — Colocynthirie — 

Byronine— Mudarine— Scillitine — Cathartine Xanthopicrine — Columbine— 

Quassiine — Lupuline — Lactucine — Ergotine — Porphyroxine  — Saponine — Smi- 
lacine — Senegine — Guiacine — Plumbagine — Cyclamine — Peucedanine — Impe- 
ratorine — Yanghinine — Meconine — Cubebine,  -  Page  524  to  527 


CONTENTS.  V 

OF  ETHERS, 

AND  THEIR  COMPOUNDS  AND  DERIVATIVES. 
OF  ETHYL  ETHERS. 

Of  the  oxide  of  ethyl,  common  ether,  erroneously  called  sulphuric  ether — Of  the 
properties  of  the  oxide  of  ethyl,  and  of  the  means  of  obtaining  it — Of  heavy  oil  of 
wine  ;  also  of  light  oil  of  wine — Of  Hoffman's  anodyne  liquor — Of  alcohol,  or 
the  hydrated  oxide  of  ethyl — Of  ethero-sulphurous  acid,  or  sulphurous  ether — 
Of  hyponitrite  of  the  oxide  of  ethyl,  called  nitric  ether,  or  nitrous  ether — Of  the 
process  for  sweet  spirit  of  nitre — Of  the  perchlorate  of  the  oxide  of  ethyl,  or  per- 
chloric  ether — Of  acetic  ether,  or  acetated  oxide  of  ethyl — Of  oxalic  ether,  or 
oxalated  oxide  of  ethyl — Of  carbonic  ether,  or  carbonated  oxide  of  ethyl — For- 
miated  oxide  of  ethyl,  or  formic  ether — Of  benzoated  oxide  of  ethyl,  or  benzoic 
ether — Of  the  tartrate  and  citrate  of  the  oxide  of  ethyl,  and  other  "  salts"  of 
ethyl,  so  called,  of  minor  importance — Of  cenanthated  oxide  of  ethyl,  or  renan- 
thic  ether,  -  -  Page  529  to  544 

Of  Simple  Ether 's,  formed  by  the  Substitution  of  another  Basacigen  Body 
for  Oxygen  in  the  Oxide  of  Ethyl;  or  for  the  Hydrogen  in  the  Water 
united  with  that  Oxide. 


Of  chloride  of  ethyl— Bromide  of  ethyl— Iodide  of  ethyl— Sulphide  of  ethyl— Sal- 
phydrate  of  the  sulphide  of  ethyl,  or  mercaptan — Bisulphide  of  ethyl — Selenide 
of  ethyl— Telluride  of  ethyl— Cyanide  of  ethyl,  -  Page  545  to  546 


Of  the  Dehydrogenation  and  Oxidation  of  Ethyl,  as  contained  in  Ether 
or  Alcohol,  and  of  the  Oxidation  of  the  Residual  Products. 

Of  the  hydrated  oxide  of  acetyl,  called  aldehyde — Ammoniated  aldehyde,  or  the  hy- 
poacetite  of  ammonia — Acetal,  a  compound  of  aldehyde  with  ether — Resin  of 
aldehyde— Metaldehyde— Elaldehyde,  -  Page  547  to  549 

Of  some  interesting  Results  of  the  Substitution  of  Chlorine,  Bromine,  Sul- 
phur, and  other  Basacigen  Bodies,  for  the  Hydrogen  or  the  Oxygen  in 
the  Compounds  of  Ethyl  and  Acetyl. 

Of  the  chlorohydrate  of  the  chloride  of  acetyl — Chloride  of  acetyl — Bromohydrate 
of  bromide  of  acetyl,  Bromide  of  acetyl,  lodohydrate  of  iodide  of  acetyl — Chlo- 
roplatinate  of  chloride  of  acetyl — Oxychloride  of  acetyl — Oxysulphide  of  acetyl 
— Chloroxalic  ether— Chloral,  -  -  Page  549  to  550 

OF  METHYL  ETHERS. 

Of  the  oxide  of  methyl,  or  methylic  ether — Of  hydrated  oxide  of  methyl,  called  py- 
roxylic,  or  wood  spirit,  methylic  alcohol — Neutral  sulphated  oxide  of  methyl — 
Acid  sulphated  oxide  of  methyl,  bisulphated  oxide  of  methyl,  sulphomethylic 
acid — Nitrated  oxide  of  methyl — Of  the  hyponitrite  of  the  oxide  of  methyl,  or 
methylic  hyponitrous  ether — Oxalated  oxide  of  methyl — Formiated  oxide  of 
methyl,  Page  551  to  555 

Reaction  of  Chlorine,  Iodine,  Cyanogen,  and  Sulphur,  with  Methyl,  and 

its  Compounds. 

Chloride  of  methyl — Iodide  of  methyl — Fluoride  of  methyl — Cyanide  of  methyl — 
Sulphide  of  methyl— Sulphydrate  of  sulphide  of  methyl,  or  methylic  mercap- 
tan— Perchloride  of  carbon,  Page  555  to  556 

OF  FORMYL  ETHERS. 

Compound  of  hydrated  oxide  of  formyl  with  oxide  of  methyl,  or  methylal — For- 
miated oxide  of  methyl — Artificial  oil  of  ants,  •  Page  556  to  557 

Compounds  of  Formyl  with  Chlorine,  Bromine,  Iodine,  and  Sulphur. 

Protochloride  of  formyl — Bichloride  of  formyl — Perchloride  of  formyl,  chloroform 

Chlorohydrate  of  the  chloride  of  formyl — Perbromide  of  formyl,  bromoform 

Periodide  of  formyl,  iodoform— Sulphide  of  formyl,  Page  558  to  559 


VI  CONTENTS. 

Of  Xylite,  or  Lignone. 
Mesiten— Mesite — Xylite  naphtha— Xylite  oil— Methal,          -  Page  559  to  560 

OF  THE  ETHEREAL  COMPOUNDS  OF  MESITYL,  OR  MESITYLENE. 

Of  the  chloride  of  mesityl— Oxide  of  mesityl— Chloride  of  pteleyle— Of  the  nitrated 
oxide  of  pteleyle — Mesitic  aldehyde,  or  the  hydrated  oxide  of  pteleyle, 

Page  560  to  561 

OF  AMYL  ETHERS. 

Of  the  hydrated  oxide  of  amyl,  or  oil  of  potato  spirit,  or  amylic  alcohol — Acetated 
oxide  of  amyl,  amylo  acetic  ether — Of  the  bromide  and  iodide  of  amyl, 

Page  561  to  562 

OF  ANIMAL  SUBSTANCES. 

Indifferent  nitrogenized  substances  common  to  the  vegetable  and  animal 

kingdoms — proteine  and  its  modifications,  -                                      -  564 

Modifications  of  proteine,           -  -                        -  565 

The  blood,  -  569 

Brain  and  nervous  matter,         -  «                         -  572 

Animal  secretions  and  excretions,         -  -  574 

Bile  and  biliary  calculi,                            -  -                         -  576 

Urine  and  urinary  calculi,          -  -  579 

Changes  which  occur  during  the  life,  growth,  and  nutrition  of  vegetables 

and  animals,             -  -  582 

Of  Respiration,  -      593 

Of  Fermentation,  -      596 

Of  the  saccharine  and  vinous  fermentations,  -  -        597 

Of  the  acetous  fermentation,  a  process  of  acetification,  -        598 

Of  the  lactic  or  viscous  fermentation,  -        598 

Of  the  Putrefactive  Fermentation,  •  -  -      604 


OF  ORGANIC  CHEMISTRY, 


OR  THE 


CHEMISTRY  OF  ORGANIC  SUBSTANCES. 


2086. ,  Under  the  appellation  of  organic  substances  are 
comprised — 

2087.  1st.  All  those  which  are  created  in  vegetables 
and  animals. 

2088.  2dly.  Such  as  are  generated  from  those  above 
mentioned,  either  by  spontaneous  changes,  aided  by  tem- 
perature or  catalysis,  or  by  reciprocal  reaction. 

2089.  3dly.  Such  as  arise  from  the  substances  created 
or  generated  as  above  described,  in  consequence  of  their 
reaction  with  inorganic  bodies. 

2090.  In  this  department  of  the  science  it  is,  perhaps,  less 
difficult  to  acquire  some  general  ideas,  than  to  make  an 
equal  progress  in  the  chemistry  of  inorganic  substances. 
The  ultimate  elements  of  vegetable  and  animal  matter  are 
fewer,  and  are  peculiarly  well  known.    But  the  light  which 
is  thrown  upon  inorganic  compounds,  by  resolving  them 
into  their  ultimate  elements,  is   much  more  satisfactory 
than  any  which  we  can,  by  the  same  means,  extend  to  or- 
ganic products.     Between  these,  ultimate  analysis  can  de- 
monstrate little  more  than  a  difference  in  the  proportions 
of  the  hydrogen,  oxygen,  carbon,  and  nitrogen,  of  which 
they  are  constituted ;  although  in  their  influence  on  vitality 
they  may  display  the  opposite  properties  of  the  most  de- 
licious food,  or  the  most  deleterious  poison;  of  delighting 
or  offending  our  senses  in  the  extreme. 

2091.  Hydrogen,  oxygen,  and  carbon,  are  the  principal 
ultimate  elements  of  vegetable  substances  ;  especially  car- 
bon, which  is  pre-eminently  essential  to  their  constitution, 
and  has  been  alleged  to  perform,  in  vegetables  and  ani- 
mals, a  part  analogous  to  that  which  silicon  performs  in 
minerals. 

2092.  In  some  essential  oils,  in  caoutchouc,  in  ammonia 

48 


372  ORGANIC  CHEMISTRY. 

in  cyanogen,  and  in  some  compounds  formed  or  derived 
from  these  substances,  there  is  no  oxygen,  while  in  oxalic 
acid,  and  some  other  oxides  of  carbon,  no  hydrogen  exists. 
But  in  no  instance,  excepting  that  of  ammonia,  and  its  hy- 
pothetical associates  amide  and  ammonium,  is  carbon  de- 
ficient; and  in  the  great  majority  of  instances,  the  three 
elements  above  named  are  indispensable  ingredients.  Al- 
though, comparatively,  nitrogen  be  found  only  in  a  few 
substances,  those  into  which  it  does  enter  are  generally 
pre-eminently  active  in  their  properties ;  and,  agreeably 
to  Liebig,  without  its  assistance,  vegetation  cannot  thrive. 
Hence,  as  he  alleges,  it  is  always  to  be  found  in  vegetable 
organs,  although  not  a  constituent  of  many  substances 
which  they  secrete  or  excrete. 

2093.  Magnesium,  calcium,  sulphur,  phosphorus,  iron, 
silicon,  bromine,  iodine,  fluorine,  are  also  found  in  minute 
proportions  in  certain  parts  of  certain  vegetable  or  animal 
products;  and  it  maybe  inferred  that  they  perform  some  use- 
ful office;  but  although  subservient,  in  an  important  degree, 
to  the  functions  of  animals  and  plants,  they  are  constituents 
neither  of  their  organic  tissues,  nor  secretory  products. 

2094.  It  is  generally  a  marked  distinction,  between  or- 
ganic and  inorganic  products,  that  the  latter  can,  in  a 
much  greater  number  of  instances,  be  imitated  by  art. 

2095.  The  incompetency  of  chemists  to  regenerate  the 
substances  analyzed  by  them,  has  caused  the  accuracy 
of  their  deductions  to  be  questioned.     Rousseau,  having 
heard  Rouelle  lecture  on  farinaceous  matter,  said  he  would 
not  confide  in  any  analysis  of  it,  till  corroborated  by  its 
reproduction  from  the  elements  into  which  it  was  alleged 
to  have  been  resolved.     I  conceive  that  an  acquaintance 
with  facts,  thoroughly  demonstrable  by  modern  chemistry, 
would  have  rendered  that  ingenious  philosopher  less  scep- 
tical.    At  first  view  it  may  seem  reasonable  to  consider 
synthesis  as  the  only  satisfactory  test  of  the  truth  of  ana- 
lysis.    But  if  when  diamond  is  burned  in  one  bell  glass, 
and  charcoal  in  another,  in  different  portions  of  the  same 
oxygen  gas,  and  subsequently,  in  each  vessel,  in  lieu  of  the 
diamond  and  charcoal,  carbonic  acid  is  found,  from  which, 
by  potassium,  carbon  may  be  liberated,  who  would  hesi- 
tate to  admit  both  substances  to  consist  of  carbon,  because 
this  element  cannot  be  recovered  in  its  crystalline  form 
from  the  gaseous  state? 


INFLUENCE  OP  HEAT  ON  VEGETABLES.  373 

Of  Organic  Hydrates. 

2096.  It  was  suggested  by  Prout,  that  as,  in  many  vege- 
table substances,  consisting  only  of  carbon,  hydrogen  and 
oxygen,  the  two  last  mentioned  elements  existed  exactly  in 
the  proportion  for  forming  water,  they  might  be  consi- 
dered as  constituted  of  water  and  carbon,  and,  conse- 
quently, as  hydrates  of  carbon. 

2097.  But  it  has  since  been  shown,  that  either  the  hy- 
drogen of  these  supposed  hydrates,  may,  in  various  in- 
stances, be  supplanted  by  other  elements  without  separa- 
ting the  oxygen;  or  that  the  oxygen  may  be  suppjanted 
without  separating  the  hydrogen. 

2093.  It  is,  however,  an  important  and  interesting  fact, 
that  almost  all  vegetable  substances  which  are  neither 
acid,  oily,  nor  resinous;  such,  for  instance,  as  gum,  sugar, 
starch,  lignin,  hold  the  elements  of  water  in  the  ratio  re- 
quisite to  form  this  liquid,  however  these  elements  may  be 
associated. 

Of  the  Influence  of  Heat  upon  Vegetables,  with  and  without 
Access  of  Air. 

2099.  When  subjected  to  distillation,  vegetable  sub- 
stances devoid  of  nitrogen,  in  the  first  place,  yield  the  water 
and  essential  oils  previously  existing  in  them.  At  a  higher 
temperature,  certain  essential  oils  or  spirits,  analogous  to 
alcohol,  resulting  from  a  new  arrangement  of  the  ultimate 
elements,  are  in  some  instances  evolved;  and  either  at  the 
same  time,  or  subsequently,  at  a  higher  temperature,  acetic 
acid,  associated  with  bituminous  or  empyreumatic  matter, 
with  carbonic  oxide  or  carbonic  acid,  and  carburetted  hy- 
drogen are  generated.  By  further  ignition,  the  volatile 
products  thus  obtained,  may  be  resolved  into  carbonic  ox- 
ide and  carburetted  hydrogen;  a  deposition  of  carbon 
in  the  solid  or  pulverulent  state,  being  always  a  concomi- 
tant of  the  change.  In  proportion  as  the  hydrogen  is  ra- 
refied by  heat,  its  capacity  to  suspend  the  carbon  appears 
to  be  diminished  (1259).  So  far  as  nitrogen  is  present, 
by  the  union  of  an  atom  of  this  element  with  carbon  or 
hydrogen,  ammonia  or  cyanogen,  or  some  of  their  com- 
pounds, may  be  generated. 

3000.  The  results  above  mentioned  evidently  proceed, 
in  a  great  measure,  from  the  superior  volatility  of  the 


374  ORGANIC  CHEMISTRY. 

hydrogen  and  oxygen,  which  causes  them  to  pass  off  into 
the  aeriform  state,  with  such  portions  of  the  carbon  as  they 
may,  under  these  circumstances,  he  capable  of  retaining. 

3001.  The  experiments  of  Sir  James  Hall  show,  that  ve- 
getable matter,  wood  for  instance,  when  subjected  to  heat 
and  pressure,  is  converted  into  a  bitumen  analogous  to 
that  of  mineral  coal.     Under  these  circumstances,  caloric 
destroys  the  organic  structure,  but  does   not  sever   the 
constituents  of  many  bodies,  which  would  be  otherwise 
partially  dissipated.      When  ignited  in  the  air,  it  were 
almost  unnecessary  to  say  that  hydrogen,  oxygen,   and 
carbon  must  yield  water  and  carbonic  acid  only.     These 
are  the  only  products  of  hydrogen   and   carbon,   when 
burned  where  there  is  an  ample  supply  of  oxygen. 

3002.  By  a  carefully  managed  heat  several  vegetable 
acids  may  be  converted  into  acids  of  a  different  kind.    In 
some  instances,  difference  of  temperature  is  sufficient  to 
vary  the  character  of  the  resulting  acid. 

Of  the  Ultimate  Analysis  of  Organic  Substances. 

3003.  The  analysis  of  vegetable  and  animal  matter  has 
been  latterly  accomplished  by  heating  the  substance  with 
oxide  of  copper,  so  as  to  oxidize  all  the  carbon  and  hydrogen, 
and  liberate,  in  the  gaseous  state,  any  nitrogen  which  may 
be  present.     The  hydrogen  has  been  in  general  estimated 
from  the  water  produced;  the  carbon,  from  the  quantity 
of  carbonic  acid.     Hence  the  products  of  the  operation 
have  been  first  passed  over  chloride  of  calcium,  and  after- 
wards subjected  to  hydrate  of  potash,  lime-water,  or  alka- 
line solutions.     The-  water  is  estimated  from  the  increased 
weight  of  the  chloride,  and  the  carbonic  acid  by  the  vo- 
lume absorbed,  or  the  increased  weight  of  the  alkaline  so- 
lution employed  for  its  detention. 

3004.  By  Messrs.  Will  and  Varrentrapp,  the  proportion 
of  nitrogen  in  a  compound  has  lately  been  ascertained  by 
heating  it  with  a  mixture  of  quicklime  and   hydrate  of 
soda,  in  a  tube  of  refractory  glass.     Under  these  circum- 
stances, the  element  in  question,  uniting  with  hydrogen  to 
form  ammonia,  is  easily  secured  by  means  of  a  dilute  so- 
lution of  chlorohydric  acid.     The  resulting  chloride  of  am- 
monium is  precipitated  by  chloroplatinic  acid,  and  the  re- 
sulting salt  is  washed  in  a  mixture  of  ether  and  alcohol. 
The  quantity  of  nitrogen  is  estimated  by  the  table  of  equi- 


ULTIMATE  ANALYSIS  OF  ORGANIC  SUBSTANCES.  375 

valents,  and  by  ascertaining  the  loss  of  weight  consequent 
to  exposure  to  a  red  heat.  Agreeably  to  the  table  of 
equivalents,  w  of  the  loss  thus  sustained  is  nitrogen. 

3005.  When  chlorine  is  present,  chromate  of  lead  is 
used  in  lieu  of  the  oxide  of  copper,  because  the  chloride  of 
copper,  being  volatile,  would  be  carried  into  the  cavities 
employed  for  the  absorption  of  water  and  carbonic  acid. 

3006.  When  liquids  are  to  be  analysed,  small  portions 
are  introduced  into  glass  bulbs  so  as  "to  alternate  in  a  tube 
with  oxide  of  copper,  or  some  other  oxidizing  agent. 

Of  the  Mode  in  which  the  Ultimate  Ponderable  Elements  of 
Organic  Bodies  are  associated. 

3007.  As  in  the  analysis  of  the  mineral  kingdom,  we  de- 
signate as  elementary,  those  substances  which  we  cannot 
analyse  further,  so,  in  examining  organic  products,  those 
substances  of  which  the  grouping  cannot  be  altered  without 
destroying  their  most  important  characteristics,  are  to  be 
viewed  as  the  elementary  principles,  by  which  the  nature 
of  compounds  is  to  be  understood  and  described. 

3008.  Liebig  alleges,  that  the  principal  object  of  organic 
chemistry,  is  the  investigation  of  the  properties  and  com- 
position of  organic  combinations,  and  the  mode  in  which 
their  elements  are  grouped.   The  idea  attached  to  the  word 
grouped  in  this  instance,  may  be  illustrated  by  contempla- 
ting the  formula  of  a  compound  in  one  way,  so  as  to  exhi- 
bit only  the  proportions  in  which  each  ultimate  element 
exists  in  it ;  in  another  way,  so  as  to  make  evident  not 
only  their  proportions,  but  their  grouping  likewise.     Thus 
the  formula  C2  O3  shows,  that  two  atoms  of  carbon  and 
three  of  oxygen  enter  into  the  composition  of  oxalic  acid ; 
but  CO  x  CO2  shows,  that  this  acid  is  composed  of  car- 
bonic oxide  CO,  and  carbonic  acid  CO2  (556,  &c.). 

3009.  In  like  manner,  cyanhydric  acid  may  be  repre- 
sented as  a  compound  of  two  atoms  of  carbon,  one  of  ni- 
trogen, and  one  of  hydrogen,  C2  N  H,  or  as  a  compound 
of  cyanogen,  C2N  and  hydrogen,  H,  formula,  C2N+H. 

3010.  The  compounds  thus  cited,  CO  carbonic  oxide,  and 
C2N  cyanogen,  are  considered  as  acting  as  compound  ra- 
dicals.    This  appellation  is  .employed  to  designate  in  these 
instances  and  in  others,  certain  groups  of  ultimate  ele- 
ments which  appeared  to  be  endowed  with  the  power,  like 
that  of  simple  ultimate  elementary  atoms,  of  entering  in 


376  ORGANIC  CHEMISTRY. 

combination  with  one  or  more  of  their  composing  atoms, 
or  of  other  simple  elementary  or  compound  atoms.1* 

301 1.  From  a  deficiency  of  better  words  I  shall  consider 
a  "  compound  radical,"  so  called  by  Liebig,  as  a  compound 
element,  when,  like  cyanogen  or  ethyl,  it  acts  as  a  simple 
element.  I  shall  restrict  the  use  of  the  name  radical, 
agreeably  to  the  definition  in  my  Inorganic  Chemistry,  to 
such  bodies  as  do  not  form  the  common  ingredient  of  an 
acid  and  a  base. 

3012.  Compound  elements,  like  cyanogen,  which,  when 
they  unite  with  an  anion  and  a  cathion,  form  with  the 
former  an  acid,  with  the  latter  a  base,  I  consider  as  be- 
longing to  the  basacigen  class  (627). 

3013.  As  on  the  one  hand,  it  is  seen  that  cyanogen  per- 
forms the  part  of  a  basacigen  body,  or  one  capable  of  pro- 
ducing acids  and  bases,  by  combining  with  radicals;  so,  on 
the  other,  we  may  perceive  ammonium,  consisting  of  hy- 
drogen and  nitrogen,  N  x  H4,  capable  like  a  metallic  radi- 
cal of  forming  compounds  with  the  basacigen  class,  which 
have  basic  properties  in  some  instances  of  great  energy. 
But  latterly,  pursuant  to  the  suggestion  of  Kane,  ammonia 
is  conceived  to  contain  a  compound  element  analogous  to 
cyanogen,  consisting  of  NH2  which  is  called  amide,  and 
which  combines  with  hydrogen  and  other  radicals,  form- 
ing compounds  called  amidurets,   capable  of  union  with 
other  definite  compounds.     Thus  it  is  inferred,  that  white 
precipitate  consists  of  amide,  mercury  and  chlorine,  NH2 
Hg  +  Cl  Hg,  the  symbol  of  amide  is  Ad,  which  being 
substituted  in  the  above,  we  have  Ad  Hg  +  Cl  Hg  for  the 
formula  of  white  precipitate/)" 

3014.  This  view  of  the  subject  is  now  generally  sanc- 
tioned, although  neither  amide  nor  ammonium  have  been 
isolated. 

3015.  In  fact,  it  has  been  shown  of  late,  that  there  are  a 

*  Strictly,  an  element  cannot  be  compound;  but  chemists,  before  the  idea  of  com- 
pound radicals  originated,  distinguished  compounds  capable  of  entering  into  com- 
bination and  of  being  separated  again,  and  transferred  to  other  compounds,  as  proxi- 
mate elements,  in  contradiction  to  simple  elements  also  called  ultimate  elements. 
Upon  this  view  of  the  subject,  the  ultimate  analysis  has  been  understood  to  convey 
the  idea  of  the  resolution  of  a  substance  into  its  simple  elements,  in  contradistinc- 
tion to  an  analysis  by  which  its  proximate  elements  are  separated.  Alcohol  sub- 
jected to  ultimate  analysis  would  be  converted  into  hydrogen,  oxygen  and  carbon, 
while  by  another  procedure,  it  may  be  resolved  into  its  proximate  elements  water 
and  ether.  I  feel  myself  authorized,  under  this  view,  to  call  those  bodies  compound 
elements,  which,  consisting  of  more  than  one  element,  act  like  simple  elements. 

I  N  is  the  symbol  of  nitrogen,  H  of  hydrogen,  Cl  of  chlorine,  Ad  of  amide,  Hg  of 
hydrargyrum  or  mercury  (556,  &c.). 


OF  COMPOUND  RADICALS.  377 

great  number  of  compound  radicals  existing  in,  or  arising 
from,  vegetable  or  animal  matter,  as  capable  of  uniting  with 
basacigen  bodies  as  do  elementary  radicals,  forming  like 
these,  oxides,  chlorides,  bromides,  iodides,  fluorides,  cyan- 
ides, sulphides,  &c.  Of  the  compounds  thus  produced, 
some  play  the  part  of  a  radical  in  an  acid,  some  an  analo- 
gous office  in  a  base  or  even  of  an  alkaline  base.  More- 
over the  acids  and  bases  thus  produced,  unite  similarly  to 
those  generated  by  a  union  of  ultimate  elements,  which 
they  are  in  many  cases  competent  to  displace  from  com- 
bination. 

3016.  Compound  organic  radicals  may  be  divided  into 
three  classes  accordingly,  as  capable  of  forming  acids,  or 
bases,  or  neither.     Hence,  they  may  be  distinguished  as 
acidifiable,  as  basifiable,  or  as  indifferent. 

3017.  The  acidifiable  compound  radicals  are  as  follows : 

Formula. 

Carbonic  oxide  or  protoxide  of  carbon,  C  O 

Cyanogen  or  bicarburet  of  nitrogen,  C2  N 

Mellon  or  sesquicarburet  of  nitrogen,  C6  N4 

Benzoile,  benzule  or  benzyl,  C14  H5  O2 

Cinnamyl  or  cinnamule,  C18  H8  O2 

Salycyl  or  salicule,  C14  H5  O4 

Acetyl  or  acetule,  -  C4  H3 

Forrnyl  or  formule,  C2  H 

3018.  The  basifiable  compound  radicals  are 

Amide, N   H2 

Ethyl  or  ethule,  -         C4  H5 

Methyl  or  methule,  C2  H3 

Cetyl  or  cetule,  -         C32  H33 

Glyceryl  or  glycerule  C6  H7 

Amyl  or  amule  -         C10  H11 

Mesityl  or  misitylene  C6  H4 

Kacodyl  or  kacodule  C4  H6 

3019.  There  are  likewise  some  subordinate  compound 
radicals. 

3020.  As  with  very  few  exceptions  in  formulae  expressing 
the  composition  of  organic  substances,  only  four  different 
letters  are  requisite,  with  the  figures  showing  the  relative 
proportions,  the  employment  of  symbols  for  that  purpose 
is  evidently  highly  advantageous.     The  student,  therefore, 


378  ORGANIC  CHEMISTRY. 

is  advised  especially  to  overcome,  by  a  proper  degree  of 
resolution,  any  repugnance  to  the  study  of  the  formulae 
above  given,  or  others  which  may  be  resorted  to  in  this 
or  in  other  modern  treatises  of  chemistry.  A  comparison 
of  their  formulae,  respectively,  will  convey  an  idea  of  the 
difference  in  composition  existing  between  the  radicals  in 
the  preceding  list. 

3021.  Agreeably  to  Liebig,  the  term  "  compound  radical" 
denotes  a  class  of  compound  bodies  possessing  the  capacity 
of  uniting  with  the  simple  elements,  and  forming,  with 
them,  combinations  analogous  in  their  properties  to  com- 
binations of  two  simple  elementary  bodies. 

3022.  From  combinations  formed  as  above  mentioned, 
the  simple  element  may  be  removed  and  replaced  by  ano- 
ther element,  simple  or  compound. 

3023'.  According  to  the  same  authority,  compound  radi- 
cals are  capable  of  combining  with  each  other,  and  of 
forming  acids  with  oxygen,  sulphur,  or  hydrogen. 

3024.  He  assumes  that  all  organic  compounds  may  be 
arranged  in  groups,  each  derived  from  their  appropriate 
compound  radical  by  the  combination  of  this  radical  with 
elementary  atoms,  and  the  union  of  the  resulting  com- 
pounds with  other  compound  bodies. 

3025.  Under  the  head  of  crystallization  (494),  I  advert- 
ed to  the  fact  that  certain  elements  may  be  substituted,  the 
one  for  the  other,  without  changing  the  crystalline  form. 
Dumas  has  latterly  held  an  analogous  doctrine  respecting 
the  substitution,  in  organic  products,  of  one  element  for  ano- 
ther, or  of  a  compound  radical  for  an  element,  without 
" altering  the  general  chemical  type"  as  he  calls  it ;  and 
would  have  the  bodies  thus  formed  grouped  together,  con- 
stituting a  natural  family.     Liebig  alleges,  that  "recipro- 
cal substitution  of  simple  or  compound  bodies,  acting  in 
the  manner  of  isomorphous  bodies,  should  be  considered 
as  a  true  law  of  nature."    This  substitution  may  take  place 
between  bodies  which  have  neither  the  same  form,  nor  any 
analogy  in   composition.     It  depends  exclusively  on  the 
chemical  force,  which  we  call  affinity. 

3026.  In  consonance  with  the  law  in  question,  Dumas 
has  found,  that  in  acetic  acid  chlorine  may  be  substituted 
for  hydrogen,  and  that  in  this  way  a  new  acid,  designated 
as  chloroacetic,  may  be  produced.  . 

3027.  This  chloroacetic  apid  is  by  him  alleged  to  be,  in 


OF  SUBSTITUTION.  379 

its  properties,  so  analogous  to  acetic  acid,  that  to  know 
the  habitudes  of  the  one,  conveys  an  idea  of  those  of  the 
other.  This  analogy  he  conceives  to  arise  from  a  chemi- 
cal law,  agreeably  to  which  the  properties  of  a  compound 
depend  rather  on  the  type  of  the  composition,  than  on  the 
particular  character  of  the  elements  which  may  have  been 
exchanged. 

3028.  Berzelius  asserts   that  chloroacetic  acid  differs 
much  from  acetic  acid  in  properties,  and  that  the  facts  ad- 
duced justify  nothing  beyond  an  opinion,  originally  ex- 
pressed upon  the  subject  by  Dumas  himself,  who,  speaking 
of  the  law  of  substitution,  admitted  it  to  be  an  "  empirical 
law,  deserving  our  attention  only  so  long  as  it  might  hold 
good" 

3029.  It  appears  to  me,  that  the  facts  of  the  cases  ad- 
verted to  in  the  support  of  the  doctrine  of  substitution, 
demonstrate  them  to  come  under  the  fourth  case  of  affi- 
nity (523),  in  which  two  bodies,  simple  or  compound, 
being  in  union,  another  body,  added  in  excess,  unites  with 
both. 

3030.  In  the  case  of  acetic  acid  exposed  to  an  excess  of 
chlorine,  there  is  the  affinity  between  hydrogen  and  chlo- 
rine, and  that  between  chlorine  and  the  elements,  with 
which  hydrogen  is  previously  combined. 

3031.  Hence  results  chlorohydric  and  a  new  acid,  called 
chloroacetic,  in  which  chlorine  may  act  as  a  radical,  as  it  is 
known  to  do  in  its  combinations  with  oxygen.     The  exist- 
ence of  chlorocarbonic  acid  demonstrates  that  the  display 
of  affinity  between  chlorine  and  oxides  of  carbon,  is  not  an 
anomaly. 

3032.  Either  of  the  classes  of  radicals  abovementioned, 
may  be  distinguished  into  primitive  and  derived  radicals. 
Mellon,  a  sesquicarburet  of  nitrogen,  is  derived  from  cy- 
anogen ;  and  acetyl  and  formyl,  from  ethyl  and  methyl. 

3033.  Being  convinced  that  in  the  present  state  of  che- 
mistry, more  even  than  heretofore,  it  is  best  to  aim  at 
general  knowledge  first,  and   afterwards  to  proceed   to 
particulars,  I  shall  not  treat  of  the  compounds  formed 
with  radicals  or  products  obtained  from  them,  under  their 
heads  respectively,  unless  where  the  substances  alluded  to 
are  of  practical  importance. 

49 


380  ORGANIC  CHEMISTRY. 

Of  Amide,  NH2. 

3034.  Ammonia,  it  will  be  remembered,  consists  of  an 
atom  of  nitrogen  and  three  of  hydrogen,  NH3.     Amide  is 
assumed  to  consist  of  one  atom  of  nitrogen  and  two  of 
hydrogen,  as  the  formula  above  given  indicates. 

3035.  The  phenomena  which  ensue  when  potassium  is 
heated  in  ammonia,  had  long  been  an  object  of  unsuccess- 
ful speculation.     The  metal,  when  so  exposed,  becomes 
converted  into  an  olive-coloured  mass,  which,  by  contact 
with  water,  is  converted  into  potash  and  ammonia. 

3036.  I  believe  that  Dr.  Kane  was  the  first  to  suggest, 
that  in  this  case  the  alkalifiable  metal  takes  the  compound 
radical,  amide,  from  the  ammonia.     Thus  a  compound  is 
generated  of  amide  arid  potassium.     When  the  amiduret 
of  potassium,   produced    as   described,   is    presented   to 
water,  this  liquid  regenerates  ammonia,  by  supplying  an 
additional  atom  of  hydrogen  to  the  amide,  while  the  po- 
tassium is,  by  simultaneous  oxidizement,  converted  into 
potash.     It  follows  that  ammonia  is  an  amiduret  of  hy- 
drogen. 

3037.  Compounds  of  amide  are  called  amides  by  Liebig ; 
amidides  by  Kane;  though  it  will  be  seen,  that  when  com- 
bined with  hydrogen,  Liebig  designates  the  resulting  com- 
pound as  a  hydruret;  in  French,  hydrure.     Consistently 
with  the  nomenclature  which  I  have  employed,  the  termi- 
nation in  ide  is  restricted  to  the  basacigen  class ;  I  shall 
therefore  use  the  termination  in  uret  for  the  compounds  of 
amide.     It  is  singular  that  Liebig  should  use  the  same 
word,  amide,  for  the  radical  and  for  its  compounds. 

3038.  As  by  the  subtraction  of  an  atom  of  hydrogen 
from  ammonia,  amide  is  generated,  so,  by  the  addition  of 
a  like  atom,  we  generate  ammonium,  of  which  I  have  al- 
ready treated  (1106). 

3039.  Liebig  represents  amide  as  acting  with  hydrogen 
in  the  place  of  an  electro-positive  radical.     Hence,  agree- 
ably to  his  language,  ammonia  is  a  "hydrure  d'amide,"  in 
English,  a  hydruret  of  amide;  or,  more  briefly,  he  calls  it 
hydramide.     Of  course,  consistently,  ammonium  is  a  bihy- 
druret,  or  bihydramide. 

3040.  The  following  formula  will  serve  to  explain  the 
composition  of  some  of  the  compounds  of  amide.    It  should 
be  kept  in  mind  that  Ad  is  the  symbol  of  amide.     White 


OP  AMIDE,  CARBONIC  OXIDE,  &C.  381 

precipitate  is  a  compound  of  amiduret  of  mercury  and  bi- 
chloride, Ad,  Hg  +  Hg  CP.  Another  amido-chloride  is 
formed  by  the  reaction  of  white  precipitate  with  alkalies, 
when  results  a  compound  of  an  amiduret  with  the  bioxide 
and  bichloride  of  mercury,  Ad  Hg  +  Hg  O2  -f  Hg  Cl2. 
Two  atoms  of  amiduret  of  mercury  unite  with  a  subsul- 
phate,  whence  we  have  a  biamido-subsulphate,  Ad  Hg2  + 
So3  2HgO.  Biamido-sesquinitrate  of  mercury  consists  of 
two  atoms  of  amiduret  of  mercury,  two  of  acid,  with  three 
of  bioxide  of  the  same  metal,  2Ad  Hg  +  2NO5  3Hg  O2. 
Amido-subnitrate,  consisting  of  an  atom  of  amiduret  and 
two  of  subnitrate,  Ad  Hg  NO5  2HgO. 

3041.  White  precipitate  has  been  designated  as  chlor- 
amide  of  mercury:  I  prefer  the  name,  above  employed, 
of  amido-chloride. 

Of  Carbonic  Oxide  as  a  Compound  Radical. 

3042.  Of  this  radical  I  have  already  treated  as  an  oxide 
of  carbon.     By  combining  with  carbonic  acid,  CO2,  it  con- 
stitutes oxalic  acid,  C2  O3.     This  acid,  by  combining  with 
hydrated  ammonia,  NH3  4-  HO,  or  more  properly  with  ox- 
ide of  ammonium,  consisting  of  the  same  ultimate  elements 
differently  grouped  (1116),  forms  neutral  oxalate  of  ammo- 
nia, so  called.     This  oxalate  is  principally  used  as  a  test 
for  lime. 

3043.  Chloroxy  carbonic  acid  is  a  product  of  the  union  of 
carbonic  oxide  with  chlorine,  of  which  some  mention  has 
been  made  (1240). 

3044.  Carbamide  is  the  name  given  to  a  compound 
formed  Ky  the  union  of  carbonic  acid  with  amide.     It  is 
obtained  by  mingling  chloroxycarbonic  acid  with  ammo- 
nia.    In  this  way  solid  white  crystals  are  produced,  con- 
sisting of  carbamide  and  chloride  of  ammonium. 

3045.  Oxamide,  C2  O2  +  Ad,  consists,  as  may  be  seen 
from  the  preceding  formula,  of  two  atoms  of  carbonic  ox- 
ide and  one  of  amide.    It  may  be  designated  as  an  amido- 
oxide  of  carbon. 

3046.  This  compound  is  obtained  in  great  purity,  by 
decomposing  oxalic  ether  by  liquid  ammonia,  or  by  heat- 
ing an  oxalate  of  ammonia  in  a  retort,  with  a  receiver  an- 
nexed.    The  oxamide  passes  into  the  receiver,  and  con- 
denses in  white  flocks.     These,  being  insoluble  in  water, 
are  depurated  by  washing  with  this  liquid  upon  a  filter. 


382  ORGANIC  CHEMISTRY. 

3047.  Oxamide  is  described  as  a  brilliant  white  powder, 
insoluble  in  alcohol,  ether,  and  in  cold  water,  but  soluble, 
in  a  small  proportion,  in  hot  water. 

3048.  Subjected  to  dry  distillation,  it  is  resolved  into 
water,  carbonic  acid,  cyanhydric  acid,  cyanic  acid,  and 
ammonia. 

3049.  Oxamide  differs  from  the  common  oxalate  of  am- 
monia, consisting  of  oxalic  acid  and  oxide  of  ammonium, 
in  having  two  atoms  less  water. 

3050.  Oxalic  ether,  which  may  be  decomposed  instantly 
by  an  aqueous  solution  of  ammonia,  consists  of  anhydrous 
oxalic  acid  and  ether,  or  oxide  of  ethyl.     The  acid  yields 
an  atom  of  oxygen  to  one  of  hydrogen  to  form  water,  by 
which  the  ether  is  converted  into  alcohol,  while  on  the 
one  side  there  remains  carbonic  oxide,  CO,  on  the  other, 
amide,  NH2,  which  by  reciprocal  union  constitute  oxamide. 

3051.  When  oxamide  is  heated  with  alkalies  or  acids, 
by  the  accession  of  an  atom  of  water,  oxalic  acid  and  am- 
monia are  generated.      The  same  result  ensues  from  the 
exposure  of  a  mixture  of  oxamide  and  water,  to  a  tempera- 
ture above  the  boiling  point. 

Of  Benzule,  Benzoile  or  Benzyle,  C14,  H5,  O2. 

3052.  The  preceding  name  is  given  to  a  compound  ra- 
dical inferred  to  exist  in  benzoic  acid,  and  in  the  essential 
oil  of  bitter  almonds,  giving  rise  to  several  interesting  com- 
pounds.    By  the  addition  of  an  atom  of  oxygen  and  an 
atom  of  water,^  it  forms  crystallizable  benzoic  acid,  which, 
like  many  other  acids,  cannot  exist  without  an  atom  of 
water,  or  some  other  base. 

3053.  By  the  substitution  of  an  atom  of  hydrogen  for  an 
atom  of  oxygen,  benzoic  acid  is  converted  into  the  pure 
essential  oil  of  bitter  almonds,  C14,  H5,  O2,  which  Liebig 
designates  as  a  hydruret  of  benzule. 

3054.  By  bringing  either  of  the  halogen  bodies  (627), 
or  various  acids  in  contact  with  this  hydruret,  with  or 
without  exposure  to  the  distillatory  process,  a  variety  of 
compounds  may  be  produced.     These  compounds,  in  com- 
position and  properties,  are  somewhat  analogous  to  ethers; 
inasmuch,  as  they  mix  either  with  ether  or  alcohol,  and  re- 
tain their  radical  with  an  energetic  affinity. 

3055.  The  hydruret  of  benzule  does  not  pre-exist  in  bit- 
ter almonds,  but  is  the  product  of  the  mysterious  catalyzing 


OF  BENZULE,  CINNAMYL.  383 

influence  of  two  substances  which  they  contain,  amigdalin 
and  emulsin,  or  synaptase,  in  an  aqueous  mixture  when 
subjected  to  distillation.  During  the  reaction  thus  in- 
duced, cyanhydric  acid  being  generated,  endows  the  resul- 
ting oil  or  hydruret,  with  a  well  known  poisonous  proper- 
ty, which,  in  the  absence  of  that  acid,  has  been  ascertained 
not  to  exist. 

3056.  Benzule  forms  a  compound  with  amide,  called 
benzamide,  by  the  reaction  of  chloride  of  benzule  with  dry 
ammoniacal  gas;  and  likewise  an  acid,  by  uniting  with 
formic  acid,  called  formobenzulic  acid.      Hippuric  acid, 
which  is  the  uric  acid  of  the  horse,  consists  probably  of 
benzamide  and  another  peculiar  acid;  or  of  hydruret  of 
benzule,  with  cyanhydric  and  formic  acids. 

3057.  According  to  Mr.  Alexander  lire,  benzoic  acid 
taken  internally  by  man,  is  discharged  in  the  urine  as  hip- 
puric  acid,  the  proportion  of  uric  acid  undergoing  a  cor- 
responding diminution. 

Cinnamyl,  C18,  H8,  O2. 

3058.  Between  this  radical  and  benzule,  there  is  much 
analogy ;  since  cinnamyl  plays  a  part  in  pure  oil  of  cin- 
namon, or  hydruret  of  cinnamyl  and  cynnamic  acid,  analo- 
gous to  that  which  benzule  plays  in  its  hydruret  and  in  ben- 
zoic acid.     In  either  case,  the  substitution  of  oxygen  for 
hydrogen,  converts  the  hydruret  into  an  acid  having  the 
same  radical. 

3059.  Cinnamyl  exists  in  oil  of  cinnamon,  which,  when 
pure,  constitutes  a  hydruret,  and  in  an  acid  called  cynnamic, 
playing  a  part  similar  to  that  which  benzule  has  been  re- 
presented as  performing  in  two  analogous  compounds.     In 
either  case,  the  oily  hydruret  may  be  converted  into  an 
acid  having  the  same  radical,  by  the  substitution  of  an 
atom  of  oxygen  for  one  of  hydrogen. 

3060.  This  radical  is  said  to  exist  in  an  oil,  separable 
from  the  balsams  of  Peru  and  Tolu. 

3061.  It  does  not  appear  that  the  compounds  formed 
with  this  radical  are  numerous  or  important. 

3062.  By  the  reaction  of  pure  colourless  nitric  acid  with 
Chinese  oil  of  cinnamon,  a  crystallized  nitrated  hydruret 
of  cinnamyl  may  be  obtained,  C18,  H8,  O2  -f  HO  +  NO5, 
which  by  addition  of  water  liberates  the  pure  hydruret  of 
cinnamyle,  C18,  H8,  O2. 


384  ORGANIC  CHEMISTRY. 

OfSalicyl,  C14,  H5,  O4. 

3063.  This  hypothetical  radical  is  inferred  to  exist  in 
the  oil  of  the  spirea  ulmaria  or  queen  of  the  meadow,  and 
in  that  evolved  from  a  neutral  crystallizable  substance, 
called  salicin,  which  may  be  extricated  from  the  leaves 
and  bark  of  any  species  of  willow,  of  which  those  parts 
have  a  bitter  taste;  and  also  from  some  species  of  poplar. 
It  was  originally  discovered  by  Buchner  and  Leroux,  in 
the  bark  of  the  salix  helix. 

3064.  This  radical  has  a  great  analogy  to  benzule  in 
properties,  as  well  as  proximity  in  composition,  as  must 
be  evident  from  a  comparison  of  their  respective  formula. 
It  is  in  fact  benzule  plus  two  atoms  of  oxygen. 

3065.  The  oil  above  mentioned  has  the  same  relation 
to  salicyl,  that  the  oil  of  bitter  almonds  has  to  benzule, 
both  being  hydrurets.    The  oil  of  spirea  is  treated  as  a  hy- 
dracid,  which  it  will  be  well  to  keep  in  mind  when  sour- 
ness is  insisted  upon,  as  a  property  peculiar  to  what  are 
improperly  called  hydracids. 

3066.  This  hydruret  may  be  obtained  in  a  state  which  is 
isomeric,  if  not  identical  with  that  in  which  it  is  extricated 
from  the  spirea,  by  distilling  one  part  of  salicin  with  three 
parts  of  bichromate  of  potash,  four  and  a  half  of  sulphuric 
acid,  and  thirty  parts  of  water. 

3067.  It  is  a  colourless,  oily,  inflammable  liquid,  with  a 
burning  taste;  density  1.731,  freezing  at  4°,  boiling  at  335.7 
when  obtained  from  spirea,  but  359.6  as  obtained  from 
salicin.     It  dissolves  easily  in  water,  alcohol  and  ether. 

3068.  Salicyl,  like  benzule,  forms  compounds  with  the 
halogen  bodies,  or  with  acids,  by  their  reaction  with  its  hy- 
druret.    The  reaction  with  ammonia  differs  from  that  of 
benzule,  as  it  unites  with  the  ultimate  element,  nitrogen, 
instead  of  amide. 

Of  Ethyl,  C4H5. 

3069.  If  this  be  really,  as  is  generally  now  believed  by 
chemists,  the  radical  in  the  well  known  liquid,  alcohol, 
certainly,  for  good  or  evil,  it  is  one  of  the  most  important 
and  interesting  compounds  in  nature. 

3070.  In  the  year  1836,  in  the  last  edition  of  my  Or- 
ganic Chemistry,  agreeably  to  the  doctrine  prevailing  at 
the  time,  I  treated  alcohol  as  a  compound  of  two  atoms  of 


OF  SALICYL,  ETHYL.  385 

water  and  one  of  etherine,  C4  H4  +  2HO.  Common  ether 
differing  from  alcohol  only  in  having  an  atom  less  of 
water  essential  to  its  constitution,  was  represented  to  be 
a  monohydrate  of  etherine,  C4  H4  4-  HO.  No  change  has 
taken  place  as  to  the  ultimate  analysis  of  these  liquids. 
It  is  only  as  to  the  grouping  of  the  ultimate  elemen- 
tary constituents,  by  which  we  have  in  ether,  C4  H5O, 
and  in  alcohol  the  formula  of  ether,  with  an  additional 
atom  of  water,  C4  H5O  -f  HO.  Thus,  instead  of  a  mono- 
hydrate  of  etherine,  ether  becomes  an  oxide  of  ethyl;  and 
alcohol,  from  a  bihydrate  of  etherine,  is  transferred  into  a 
hydrated  oxide  of  ethyl. 

3071.  Agreeably  to  either  view,  the  transformation  of 
alcohol  into  ether  requires  only  the  removal  of  an  atom  of 
water. 

3072.  It  is  well  known  that  common  ether  may  be  ob- 
tained by  the  distillation  of  alcohol  with  sulphuric  acid, 
and  that  when,  to  the  materials  employed  for  this  purpose, 
an  acid,  or  a  salt  containing  an  acid,  is  added,  an  etherial 
compound  of  ether  with  the  acid,  having  more  or  less  ana- 
logy with  common  ether  in  properties,  may  be  obtained. 

3073.  There  is  hardly  an  acid,  with  which  a  peculiar 
ether  bearing  its  name  has  not  been  formed,  such  as  nitric 
ether,  acetic  ether,  tartaric  ether,  oxalic  ether,  muriatic 
ether,  &c. 

3074.  The  rationale  is  evident :  as  to  convert  alcohol 
into  ether,  the  removal  of  an  atom  of  water  is  all  that  is 
requisite;  to  generate  -any  other  ether,  it  is  only  necessary 
that  this  oxide,  in  its  nascent  state,  shall  be  in  contact  with 
an  acid,  or  be  presented  to  any  basacigen  body  in  union 
with  hydrogen ;  so  that  the  ethyl  may  be  deoxidized  by 
the  formation  of  water,  and  presented  naked  to  the  basaci- 
gen element. 

3075.  Under  this  view  of  the  composition  of  ether,  it 
is  unaccountable,  that  this  oxide  will  not  combine  with 
acids,  excepting  when  it  is  in  a  nascent  state;  but  this  ob- 
jection may  apply  also  to  the  existence  of  etherine  as  the 
base  of  the  ethers. 

3076.  It  does  not  appear  that  ethyl  has  ever  been  iso- 
lated.    I  have  not  only  distilled  pure  ether  from  potas- 
sium, without  decomposing  it,  but  have  likewise  cohobated 
it  with  potassium  in    a    glass  tube,  hermetically  sealed. 
The  lower  end,  to  which  the  contents  naturally  subsided, 


386  ORGANIC  CHEMISTRY. 

was  kept  boiling  by  a  water  bath  for  several  days,  without 
being  decomposed  more  than  partially.  The  potassium 
became  coated  with  a  white  crust,  which  being  removed, 
the  metal  appeared  in  its  metallic  state. 

3077.  The  etherial  compounds  of  ethyl  may  be  classi- 
fied as  forming  one  order  of  ethyl  ethers. 

3078.  We  have  then,  in  this  order,  the  following  class- 
es:— Class  1st.  Simple  ethers,  formed  by  the  union  of  ethyl 
with  any  basacigen  element  which  are  named  after  such 
element. 

3079.  In  this  class  we  have  the 


Oxide 

Chloride 

Bromide 

Iodide 

Sulphide 

Selenide 

Telluride 


of  ethyl, 


3080.  Complex  ethers  are  formed  by  the  union  of  an 
acid  with  any  one  of  these.     Excepting  those  formed  with 
the  oxacids  and  sulphydric  acid,  there  are  no  ethers  in 
this  class.    The  oxacid  ethers  may  be  considered  as  form- 
ing a  genus  comprising  an  etherial  compound  for  almost 
every  acid  of  importance. 

3081.  There  is  only  one  sulphacid  ether,  mercaptan,  or 
the  sulphydrate  of  the  sulphide  of  ethyl. 

3082.  In  consequence  of  its  being  obtained  by  the  dis- 
tillation of  sulphuric  acid  with  alcohol,  the  oxide  of  ethyl 
was  formerly  called  sulphuric  ether,  and  is  still  mentioned 
under  that  name  in  commerce,  agreeably  to  the  opinion 
that  it  consisted  of  water  and  etherine,  as  other  ethers 
consisted  of  etherine  and  an  appropriate  acid.     In  the  last 
edition  of  my  Organic. Chemistry,  I  designated  this  oxide 
as  hydric  ether.    It  is  a  curious  consequence  of  the  change 
which  has  taken  place,  as  above  described,  in  the  prevail- 
ing opinion  on  this  subject,  that  the  name  above  mentioned 
is  now  due  to  alcohol,  which,  as  respects  composition,  is, 
in  fact,  hydric  ether.    Yet  it  differs  from  ethers  in  general 
in  having  a  strong  affinity  for  water  in  all  proportions. 

3083.  It  may  be  well  to  premise,  that  I  shall  adopt  for 
the  oxide  of  ethyl,  when  not  particularly  desirous  to  recall 
its  chemical  composition,  the  usual  name  of  ether,  which 


OF  SALICYL,  ETHYL.  387 

it  may  claim  by  prescription,  however  temporarily  it  may 
have  been  otherwise  designated. 

3084.  As  alcohol  differs  from  ether  only  in  the  presence 
of  an  atom  of  water,  it  follows  that  any  chemical  reaction, 
which  should  effect  the  removal  of  that  atom,  ought  to 
convert  it  into  ether.     Yet,  excepting  the  reaction,  during 
distillation,  with  one  or  two  chlorides,  a  resort  to  which 
would  not  be  found  economical,  the  conversion  of  one  li- 
quid into  the  other  is  accomplished  by  a  most  complicated 
and  intricate  play  of  affinities,  which  has  been  a  most  pro- 
lific source  of  discussion  among  the  most  eminent  che- 
mists.    Nevertheless,  this  subject  is  still  debateable,  not- 
withstanding that  much  light  has  been  thrown  upon  the  ac- 
companying phenomena. 

3085.  It  may  be  well  for  the  student  to  recollect  the 
relative  composition  of  these  important  liquids,  and  that 
the  conversion  of  one  into  the  other  arises  from  the  sub- 
jection of  alcohol,  mingled  with  certain  acids,  to  the  dis- 
tillatory process. 

3086.  When  sulphuric  acid  is  employed  as  is  usual,  the 
first  result  is  a  combination  between  two  atoms  of  this 
acid,  one  of  oxide  of  ethyl,  and  one  of  water,  forming  what 
has  been  called,  heretofore,  sulphovinic  acid,  or  what  Lie- 
big  designates  as  the  acid  sulphate  of  the  oxide  of  ethyl. 

3087.  Evidently  it  would  be  more  properly  defined  as  a 
double  sulphate  of  ether  and  water  ;*  for  as,  what  is  called 
concentrated  sulphuric  acid,  when  deprived  of  water  as  far 
as  this  effect  can  be  produced  by  ebullition,  is  a  sulphate 
of  water;  sulphovinic  acid,  consisting  of  one  atom  of  this 
sulphate,  and  one  atom  of  sulphate  of  the  oxide  of  ethyl, 
must  be  a;'double  sulphate  of  the  oxide  of  ethyl,  and  wa- 
ter.f 

3088.  So  long  as  the  proportion  of  water  present  in 

*  The  water  in  hydrous  sulphuric  acid,  has  been  latterly  considered  as  acting  as 
a  base,  so  that  when  a  metal,  by  contact  with  the  acid,  displaces  hydrogen,  it  is  mere- 
ly a  case  in  which  one  radical  supplants  another.  Agreeably  to  a  new  doctrine,  all 
the  sulphur  and  oxygen  present,  acts  as  a  compound  radical,  and,  as  such,  is  trans- 
ferred from  one  radical  to  another;  but  this  I  think  I  have  shown  to  be  untenable. 
See  Effort  to  refute  the  Arguments  in  favour  of  the  existence  of  Compound  Radicals 
in  Amphide  Salts,  6,  92. 

t  In  order  to  understand  the  above  given  explanation,  it  should  be  recollected, 
that  the  boiling  point  of  diluted  sulphuric  acid  rises,  as  the  proportion  of  water  in 
union  with  it  lessens,  till  it  attains  the  point  at  which  the  sulphate  of  water  itself 
vaporizes,  which  is  about  600°  :  also,  that  the  affinity  of  concentrated  sulphuric  acid 
for  water  is  so  great,  as  to  enable  it  to  abstract  the  elements  of  this  liquid  from  or- 
ganic substances;  in  which  case  they  are  blackened,  and  said  to  be  carbonized,  in 
consequence  of  the  evolution  of  carbon. 
50 


388  ORGANIC  CHEMISTRY. 

the  mixture  of  sulphuric  acid  and  alcohol,  is  adequate  to 
keep  the  temperature  sufficiently  low,  the  ether,  in  the 
double  sulphate,  being  more  volatile  than  the  water,  ex- 
isting in  excess  in  the  solution,  yields  the  acid  to  this  li- 
quid, and  comes  over,  accompanied  by  a  proportional  quan- 
tity of  steam,  and  at  the  outset,  of  alcoholic  vapour.  Thus 
ether,  alcohol,  and  water,  being  partially  removed,  the  pro- 
portion of  acid  relatively  to  the  residual  materials,  is  in- 
creased: but  as  this  takes  place,  its  avidity  for  water  aug- 
ments, and  the  boiling  point  of  the  mixture  rises.  In 
consequence  of  the  increased  avidity  for  water,  the  acid 
takes  from  a  portion  of  the  ether,  C4  H5O,  an  atom  of  each 
of  the  elements  of  this  liquid,  HO.  Thus  etherine  is 
evolved,  C4  H4. 

3089.  Meanwhile  the  increased  heat  causes  a  portion 
of  the  etherine  to  give  up  the  whole  of  its  hydrogen  to  a 
part  of  the  oxygen,  of  a  portion  of  the  acid.     Hence  sul- 
phurous acid  and  carbon  are  evolved;  the  one  being  indi- 
cated by  the  carbonaceous  colour,  the  other  by  its  well 
known  suffocating  fumes.     Under  these  circumstances,  a 
triple  compound,  consisting  of  sulphuric  acid  and  oxide  of 
ethyl,  and  a  portion  of  undecomposed  etherine,  being  form- 
ed, comes  over  with  sulphurous  acid  and  ether,  forming  a 
yellow  liquid.     When  this  liquid  is  deprived  of  its  sulphu- 
rous acid  by  ammonia,  or  any  other  alkaline  base,  and  the 
ether  is  removed  by  distillation,  the  residue  is  the  liquid 
long  known  as  oil  of  wine,  being  the  efficient  and  charac- 
teristic ingredient  of  Hoffman's  anodyne,  erroneously  re- 
presented in  several  European  works  as  a  mere  mixture  of 
alcohol  and  ether.     The  preferable  mode  to  isolate  the  oil 
of  wine,  is  to  expose  the  yellow  liquid,  in  vacuo,  over  sul- 
phuric acid  in  one  capsule  and  slaked  lime  in  another. 
The  sulphurous  acid  is  absorbed  by  the  lime,  the  ether  by 
the  sulphuric  acid.     The  quantity  of  acid  in  the  oil  varies 
with  the  mode  of  isolation;  being  greatest  when  the  last 
mentioned  mode  is  resorted  to. 

3090.  The  word  ether  was  originally  employed  to  desig- 
nate a  supposed  elastic  aeriform  matter,  vastly  more  rare 
and  subtile  than  air.    It  is  still  used  in  that  sense  as  an  ap- 
pellation for  the  matter,  which  is,  according  to  the  undula- 
tory  theory,  the  medium  by  which  luminous  bodies  radiate 
light.     By  analogy,  the  word  ether  was  employed  to  de- 
signate a  liquid  which  bore  the  same  relation  to  other 


OF  ACETYL.  389 

liquids,  as  ether  proper  to  air.  This  appellation  has  natu- 
rally been  extended  to  other  liquids  analogous  in  proper- 
ties and  composition.  Of  ethers  in  general,  common  ether 
may  be  considered  as  the  best  exemplification.  What 
mainly  distinguishes  the  liquids  thus  called,  from  alcohol, 
is  their  very  inferior  miscibility  with  water.  Many  of 
them  are,  however,  heavier  than  water,  so  that,  upon  the 
score  of  density,  they  do  not  merit  to  be  distinguished  as 
etherial. 

3091.  It  will  be  seen  that  there  are  several  hydrates, 
formed  with  other  compound  radicals,  which  are  congeners 
of  alcohol  in  composition,  and,  to  a  limited  extent,  resem- 
ble it  in  properties. 

3092.  Generally,  substances  considered  as  etherial  are 
susceptible  of  distillation,  are  inflammable,  little  soluble  in 
water,  but  highly  susceptible  of  union  with  alcohol,  essen- 
tial oils,  and  resins.     They  are,  for  the  most  part,  fragrant 
and  stimulating  to  the  taste,  affecting  the  animal  nerves 
powerfully  when  inhaled,  or  swallowed,  even  in  a  minute 
quantity. 

OfAcetyl,  C4  H3. 

3093.  The  preceding  name  has  been  given  to  a  hypo- 
thetical sub  radical  containing  the  same  number  of  atoms 
of  carbon  as  ethyl,  with  three  atoms  of  hydrogen  instead 
of  five.     This  radical  is  inferred  to  play  the  same  part,  in 
a  liquid  lately  discovered  and  called  aldehyde,  that  ethyl 
does  in  alcohol.     In  fact,  the  only  difference  in  composi- 
tion existing  between  these  liquids,  is  that  between  their 
radicals;  the  former  being  produced  from  the  latter  by  the 
removal  of  two  atoms  of  hydrogen. 

3094.  Acetyl  is  chiefly  interesting  as  the  radical  of  the 
important  acid  of  vinegar,  designated  by  modern  chemists 
as  acetic  acid.     This  acid,  in  the  hydrated  state,  in  which 
alone  it  is  capable  of  isolation,  results  from  the  addition  of 
two  atoms  of  oxygen  to  aldehyde.     By  the  lesser  addition 
of  one  atom  of  the  same  element,  another  acid  has  been 
made,  called  acetous  acid,  or  aldehydic  acid.* 

*  As  both  this  acid  and  acetic  acid  have  the  same  radical,  the  compound,  having 
the  lesser  proportion  of  oxygen,  should  terminate  in  ous  (1052,  &c.).  Hence  the 
acid  in  question  should  be  called  aldehydous  acid,  if  named,  so  as  to  show  its  deriva- 
tion from  aldehyde,  and  acetic  acid  should  be  called  aldehydic  acid;  but  aldehyde 
itself  enters,  as  an  acid,  into  an  ammoniacal  compound,  the  formation  of  which  is  a 
precursory  step  in  obtaining  it  in  a  state  of  purity.  Of  course,  if  these  compounds 


390  ORGANIC  CHEMISTRY. 

3095.  By  Liebig,  olefiant  gas  is  treated  as  a  hydruret 
of  acetyl,  C4  H3  +  H  =  C4  H4,  which  is  just  double  the 
quantity  of  carbon  and  hydrogen  contained  in  a  volume  of 
olefiant  gas.     But,  according  to  Berzelius,  the  two  atoms 
of  carbon,  and  two  atoms  of  hydrogen,  in  a  volume  of  this 
gas,  constitute  an  independent  radical,  which  he  calls  elayl. 
Agreeably  to  Liebig's  view,  olefiant  gas  is  isomeric  with 
etherine,  or  etherole,  the  name  given  to  etherine  by  him. 

3096.  Agreeably  to  the  view  of  the  former,  the  oil  re- 
sulting from  the  reaction  of  olefiant  gas  with  chlorine,  is  a 
chlorohydrate  of  chloride  of  acetyl,  C4  H3  Cl  +  HC1,  while, 
if  the  Berzelian  idea  be  adopted,  it  consists  of  two  atoms 
of  elayl  and  two  of  chlorine,  C4  H4  Cl2. 

3097.  When  this  compound  is  dissolved  in  a  solution  of 
potash  and  alcohol,  it  is  decomposed  into  chlorohydric 
acid,  which  forms  water  and  chloride  of  potassium  with 
the  potash,  and  a  compound,  which  escapes  in  the  gaseous 
form,  consisting  of  C4  H3  Cl.    The  composition  of  this  gas 
is  evidently  such,  that  it  may  be  considered  as  a  chloride 
of  acetyl;  and  its  formation  must  be  regarded  as  confirm- 
ing the  view  taken  by  Liebig  of  the  composition  of  the  oil 
of  the  Dutch  chemists.     Bromine,  like  chlorine,  on  being 
presented  to  olefiant  gas,  produces  a  compound,  which 
may  either  be  considered  as  a  bromohydrate  of  the  bro- 
mide of  acetyl,  or  simply  as  a  bromide  of  elayl,  in  other 
words,  of  olefiant  gas;  but  which,  by  reaction  with  the  al- 
kalies, evolves  a  gas,  the  composition  of  which,  it  would 
seem,  can  only  be  reconciled  with  the  idea  of  a  bromide  of 
acetyl.    The  action  of  iodine  is  analogous,  but  not  so  well 
ascertained.    The  product  is  pulverulent  in  its  consistency, 
but  in  other  respects  resembles  that  which  results  from  the 
reaction  of  chlorine  with  olefiant  gas. 

OfMesityl  or  Misitylene*  C6  H4. 

3098.  The  vapour  of  pure  acetic  acid,  in  passing  through 
a  red-hot  porcelain  tube,  is  decomposed,  yielding  a  colour- 
be  all  considered  as  oxacids  of  acetyl,  as  I  think  would  be  more  proper,  agreeably  to 

the  nomenclature  adopted  in  analogous  instances,  their  names  would  be  acetic  acid, 
acetous  acid,  and  hypoacetous  acid.  But  aldehyde,  as  a  congener  of  alcohol,  is,  per- 
haps, preferably  designated  as  a  hydrated  oxide  of  acetyl. 

*  Liebig  does  not  introduce  this  radical  into  his  general  list  of  radicals,  but  treats 
of  it  as  a  product  of  the  decomposition  of  acetyl.  The  same  course  is  pursued  in 
respect  to  kacodyl,  although  this  contains,  as  will  soon  appear,  arsenic,  an  element 
which  does  not  exist  in  acetyl.  It  will  also  be  found  that  he  places  sugars  under 
ethyl,  as  yielding  ethyl  by  their  decomposition.  This  does  not  appear  to  me  judicious, 
because,  by  the  same  rule  that  mesityl  is  placed  under  acetyl,  ethyl  should  come 


OF  MESITYL.  391 

less,  limpid,  volatile,  inflammable,  empyreumatic  liquid, 
which  has  received  the  name  of  acetone.  This  liquid  may 
be  obtained,  also,  by  dry  distillation,  from  any  dry  acetate 
of  an  alkali  or  alkaline  earth;  also  by  heating  sugar  of 
lead  with  quicklime,  by  means  of  an  iron  bottle.  When 
acetone  is  distilled  with  half  its  volume  of  fuming  sulphuric 
acid,  upon  the  liquid  which  passes  into  the  receiver  a  yel- 
low oil  swims,  which,  after  being  washed  with  water,  is 
rectified.  The  first  portions  contain  a  little  acetone,  which 
is  removed  by  redistillation,  by  means  of  a  water  bath. 

3099.  This  oil  is  mesityl,  being  a  colourless,  oleaginous, 
inflammable  liquid,  having  a  feeble  odour,  recalling  that  of 
garlic.  It  is  lighter  than  water.  With  alkalies  it  under- 
goes no  change.  With  sulphuric  acid,  nitric  acid,  and 
chlorine,  its  habitudes  resemble  those  of  benzule.  Its  com- 
position is  equivalent  to  two  atoms  of  acetone,  less  two 
atoms  of  water. 

Two  atoms  of  acetone         2C3  H3O  =  C6  H6  O2 
Deduct  two  atoms  of  water  H2  O2 

And  we  have  mesityl  C6  H4 

4000.  Acetone  was  inferred  to  be  an  hydrated  oxide  of 
mesityl;  but  Dr.  Kane,  the  author  of  the  inference,  has 
admitted  that  there  are  not  sufficient  grounds  to  justify 
him  in  retaining  that  idea  of  its  composition.     Acetone 
has  peculiar  and  useful  powers  as  a  solvent.     Many  salts 
\vhich  are  soluble  in  both  alcohol  and  water,  are  insoluble 
in  acetone,  especially  chloride  of  calcium  and  hydrate  of 
potash.     It  burns  with  white  flame,  and  has  nearly  the 
same  density  as  alcohol.     Its  taste  is  disagreeable,  having 
some  analogy,  however,  with  that  of  peppermint. 

4001.  Metascetone,  C6  H5O,  is  the  name  given  to  a  co- 
lourless, volatile,  fragrant,  inflammable  liquid,  soluble  in  al- 
cohol and  ether,  but  insoluble  in  water,  and  which  boils  at 
182.5.     It  may  be  considered  as  two  atoms  of  acetone, 
minus  one  atom  of  water,  C6  H6  O2  —  HO  =  C6  H5O,  me- 
tascetone. 

4002.  This  liquid  is  generated  simultaneously  with  ace- 
tone, when  one  part  of  sugar,  and  eight  parts  of  powdered 
quick-lime,  are  subjected  to  distillation. 

under  sugar.  But  where  a  radical  only  furnishes  the  elementary  ingredients  to 
another  compound,  or  derives  its  ingredients  from  one,  I  do  not  conceive  that  any 
connexion  in  classification  should  be  made  between  it  and  the  substances  whence  it 
is  obtained,  or  to  the  formation  of  which  it  contributes. 


392  ORGANIC  CHEMISTRY. 

4003.  Mesityl  forms  various  compounds  with  the  basa- 
cigen  bodies,  which  it  is  not  deemed  proper  to  describe 
here.     With  sulphuric  acid  it  forms  a  compound  which 
affords  soluble  salts  with  baryta  and  lime. 

Reflections  on  the  Relation  or  Analogy  between  Acetyl,  Ethyl, 
Amide,  and  Ammonium. 

4004.  By  the  addition  of  an  atom  of  water,  HO,  to  am- 
monia, NH3,  an  oxide  of  ammonium  is  produced,  NH4O, 
which  is  the  base  of  ammoniacal  oxysalts  (1116).     In  like 
manner  it  was  supposed  by  Boullay  and  Dumas,  that  by 
the  acquisition  of  an  atom  of  water,  etherine,  a  hydruret  of 
carbon  (1267),  was  enabled  to  play  the  part  of  a  base  in 
the  neutralization  of  oxacids.   This  idea  was,  for  some  time, 
generally  sanctioned,  and  hence,  in  the  last  edition  of  this 
Compendium,  etherine  was  represented  as  the  base  of  all 
the  ethers  which  have,  in  this  edition,  been  represented  as 
having  ethyl  as  their  radical,  and  its  oxide  for  their  base. 

4005.  It  has  already  been  mentioned  (1109),  that  agree- 
ably to  the  doctrine  advanced  by  Berzelius,  and  generally 
adopted,  in  the  salts  formed  by  presenting  ammonia  to  li- 
quid acids,  the  elements  of  the  resulting  base  exist,  not  as 
a  hydrate  of  ammonia,  but  as  an  oxide  of  ammonium.     So 
far  as  an  analogy  with  the  habitudes  of  ammoniacal  com- 
pounds would  influence  the  view  adopted,  a  corresponding 
conception  would  be  created,  that  in  etherial  compounds 
the  base  should  be  an  oxide  of  ethyl,  not  a  hydrate  of 
etherine.     Besides  the  correspondence  thus  existing,  there 
was  no  small  analogy  between  the  relation  borne  by  amide 
to  ammonium,  and  acetyl  to  ethyl :  the  only  discordancy 
being,  that  the  susceptibility  of  forming  acids,  displayed 
by  acetyl,  has  not  been  observed  in  amide. 

Of  the  Compound  Hypothetical  Radical,  Kacodyl,  C4  H6  AS, 

Symbol  Kd. 

4006.  The  substance  to  which  the  name  above  men- 
tioned has  been  given,  is  one  of  the  many  compound  radi- 
cals of  which  the  existence  has  lately  been  inferred  by 
chemists.    It  has  the  unusual  feature  of  containing,  among 
its  essential  constituents,  an  atom  of  a  metallic  radical, 
arsenic.     Its  name  is  from  *«*«$,  bad,  and  *Jx  odour. 

4007.  The  protoxide  of  kacodyl  constitutes  a  fetid,  viru- 
lently poisonous,  etherial,  spontaneously  inflammable,  vola- 


OF  KACODYL  393 

tile,  limpid  liquid,  long  known  as  the  fuming  liquor  of  Cadet, 
its  discoverer.  This  liquid,  now  called  alcarsin,  is  obtained 
by  distilling  dry  acetate  of  potash  with  an  equal  weight  of 
arsenious  acid.  By  digesting  alcarsin,  or  oxide  of  kaco- 
dyl,  in  chlorohydric  acid,  chlorine  taking  the  place  of  oxy- 
gen, a  chloride  of  kacodyl  results.  From  this  the  radical 
is  separated,  by  reaction  with  metallic  zinc,  at  the  tempe- 
rature of  230°,  and  removing  the  resulting  chloride  of  zinc 
by  water. 

4008.  Kacodyl  is  an  etherial,  limpid,  spontaneously  in- 
flammable liquid  having  a  nauseous  odour.     It  sinks  in 
water  without  dissolving,  but  is  soluble  in  alcohol  or  ether. 
It  boils  at  338°.     At  a  red-heat  its  vapour  is  resolvable 
into  arsenic,  olefiant  gas,  and  light  carburetted  hydrogen. 

4009.  The  following  compounds  are  formed  by  this  ra- 
dical, of  which  it  does  not  appear  consistent  to  treat  par- 
ticularly here. 


Kd  O  Alcarsin  Oxide 

KdCl  Chlorarsin  Chloride 

Kd  S  Sulpharsin  Sulphide 

Kd  Cy  Cynarsin  Cyanide 

Kd  O3  +  HO  Alcargen  Hydrated  trioxide 


of  kacodyl. 


4010.  Agreeably  to  the  preceding  formulae  of  the  com- 
pounds of  kacodyl,  it  may  be  seen  that,  excepting  alcar- 
gen,  they  differ,  in  composition,  only  as  respects  one  of 
their  ingredients,  a  basacigen  element,  to  the  presence  of 
which  they  owe  the  diversity  of  the  names  given  in  one  of 
the  lists. 

4011.  Alcargen,  or  kacodylic  acid,  differs  from  the  rest 
in  holding  an  atom  of  water,  HO. 

4012.  Liebig  supposed  the  bodies  in  question  each  to 
consist  of  an  atom  of  acetyl  and  an  atom  of  arsenuretted 
hydrogen,  As  H3,  not  grouped  into  one  radical;  but  Ber- 
zelius  suggested  that  they  were  so  grouped,  and  this  Bun- 
sen  has  proved  to  be  true,  by  isolating  kacodyl  as  above 
described. 

4013.  It  may,  however,  be  well  to  point  out,  that  the 
composition  of  kacodyl  is  consistent  with  the  idea  of  Lie- 
big,  since  an  atom  of  acetyl,       -  C4  H3 
and  an  atom  of  arsenuretted  hydrogen,  As  H3 
are  equivalent  to  an  atom  of  kacodyl,                  C4  H6  As 


394  ORGANIC  CHEMISTRY. 

4014.  I  object  to  the  unmeaning  names  above  given,  as 
not  conveying  any  idea  of  composition.     Hence  I  shall 
use  those  which  indicate  the  composition. 

4015.  Alcargen,  more  significantly  called  kacodylic  acid, 
or  hydrated  trioxide,  agreeably  to  the  nomenclature  which 
would  make  hydrous  sulphuric  acid  a  sulphate  of  water, 
would  be  a  kacodylate  of  water. 

Of  Methyl,  C2H3. 

4016.  After  it  had  become  evident  that  the  etherial  com- 
pounds, derived  from  the  reaction  of  alcohol  with  acids  or 
halogen  bodies,  had  all  a  common  compound  radical,  che- 
mists were  naturally  led  to  infer,  that  there  might  be  other 
series,  similar  in  their  nature,  having  the  same  electro- 
negative ingredients  united  with  other  compound  radicals. 
These    speculative   inferences   first  received   a  practical 
verification,  from  the  labours  of  Dumas  and  Peligot  re- 
specting the  composition  and  combinations  of  pyroxilic 
spirit,  obtained  from  the  products  of  the  destructive  distil- 
lation of  wood  or  other  organic  products.     From  the  in- 
vestigations of  these  chemists  it  has  been  made  evident, 
that  pyroxilic  spirit  is  the  alcohol  of  a  series  of  compounds 
having  methyl  as  a  radical. 

4017.  The  compounds  of  methyl  with  the  basacigen 
class,  and  those  formed  between  its  oxide  and  acids,  are 
produced  by  reactions  with  methylic  alcohol  or  ether,  or 
their  products,  similar  to  those  by  which  analogous  com- 
pounds with  ethyl  are  effected.    There  is,  likewise,  a  great 
analogy  in  the  properties  of  the  two  series;  yet  methylic 
ether  (or  in  other  words  the  oxide  of  methyl  the  com- 
pound which  is  the  congener  of  ether  proper),  is  gaseous, 
in  lieu  of  existing  like  ether  as  a  liquid.     Moreover,  a  ni- 
trated oxide  of  methyl,  or  a  true  methylic  nitric  ether,  is 
readily  generated  when  wood  spirit  (hydrated  oxide  of  me- 
thyl), is  presented  to  nitric  acid.     This  etherial  compound, 
has  no  congener  among  those  of  ethyl,  because  the  reac- 
tion, between  nitric  acid  and  alcohol,  is  attended  by  a 
reciprocal  decomposition,   by  which  hyponitrous  acid  is 
evolved  and  combines,  while  nascent,  with  oxide  of  ethyl, 
existing    in   an   undecomposed    portion   of   the   alcohol. 
Hence  it  arises,  that  hyponitrous  ether  is  generated  in- 
stead of  nitrated  oxide  of  ethyl.     On  the  other  hand  no 
hyponitrite  of  the  oxide  of  methyl,  results  from  the  reac- 


OF  FORMYL. 


395 


tion  of  nitric  acid  with  wood  spirit ;  since  the  decompo- 
sition, requisite  to  the  development  of  hyponitrous  acid, 
does  not  ensue.  Consequently,  Liebig  alleges  that  no  con- 
gener of  hyponitrous  ether  exists  among  the  etherial  com- 
pounds of  methyl. 

4018.  I  have  recently  been  enabled  to  fill  up  this  inter- 
val in  the  methyl  series,  by  subjecting  wood  spirit  to  a  hy- 
ponitrite,  in  contact  with  a  diluted  acid. 

Of  Formyl. 

4019.  Formyl  has  a  relation  to  methyl,  similar  to  that 
which  acetyl  has  to  ethyl.     In  either  case,  there  is  a  radi- 
cal differing  from  another,  only  by  the  subtraction  of  two 
atoms  of  hydrogen. 

4020.  The  hydrated  oxide  of  formyl  is  inferred  to  exist 
in  a  liquid,  obtained  by  the  reaction  of  two  parts  of  wood 
spirit  with  three  of  sulphuric  acid,  three  of  water,  and  two 
parts  of  peroxide  of  manganese.     An  inflammable,  etherial, 
colourless  liquid,  of  an  agreeable  aromatic  odour  and  sus- 
ceptible of  solution  in  three  parts  of  water,  was  thus  pro- 
cured.    This  liquid  has  been  inferred  to  be  a  compound 
of  two  atoms  of  oxide  of  methyl,  and  one  of  hydrated  ox- 
ide of  formyl. 

4021.  There  are  in  the  formyl   series  no  compounds 
corresponding  to  aldehyde,  or  acetous  acid.     The   only 
oxide  is  that  long  known  as  formic  acid,  from  its  having 
been  first  obtained  from  ants.     This  acid  is  obtained  from 
formyl,  as  acetic  acid  from  acetyl,  by  the  addition  of  three 
atoms  of  oxygen. 

4022.  Agreeably  to  Liebig,  three  chlorides  of  formyl 
have  been  isolated.     The  perchloride  has  been  known  for 
a  good  while,  having  been  obtained  by  distilling  alcohol 
with  hypochlorite  of  lime.      It  was  obtained  about   ten 
years  since  in  this  country  by  Gurthrie,  and   for  some 
time  confounded  with  the  etherial  oil  of  olefiant  gas,  which 
is  now  considered  by  Liebig  as  the  chlorohydrate  of  the 
chloride  of  acetyl. 

Amyl,  C10  H11. 

4023.  A  peculiar  liquid  was  noticed  by  Scheele  to  ac- 
company potato  spirit.      Subsequently,  by  Pelletier,  Ca- 
hours  and  Dumas,  it  was  inferred  to  be  the  hydrated  oxide 
of  a  peculiar  compound  radical,  to  which  the  name  at  the 

51 


396  ORGANIC  CHEMISTRY. 

head  of  this  article  was  given.  It  follows  that  this  liquid 
must  be  a  congener  of  alcohol,  its  formula  being  C10  H11 
+  HO. 

4024.  The  amyl  series  of  compounds  corresponds  with 
those  of  other  radicals  to  a  certain  extent,  but  is  upon  the 
whole  very  incomplete,  having  no  oxide  to  occupy  the  place 
of  a  congener  of  ether.     Even  the  chloride  does  not  appear 
to  be  permanent  per  se.     The  bromide  and  iodide  are  more 
enduring,  and  in  their  habitudes  somewhat  analogous  to 
corresponding  combinations  in  the  series  of  other  radicals. 

4025.  Yet  in  the  case  of  sulphoamylic  acid,  the  ana- 
logy is  well  supported  to  other  etherial  double  sulphates, 
such  as  sulphovinic  acid,  and  there  have  been  formed  sul- 
phoamylates  capable  of  decomposition  and  of  reproducing 
the  hydrated  oxide,  potato  spirit. 

4026.  An  amylic  acetic  ether  has  been  produced,   by 
distilling  two  parts  of  acetate  of  potash,  one  part  of  potato 
spirit,  and  one  part  of  sulphuric  acid.     As  respects  in- 
flammability, volatility  and  insusceptibility  of  mixture  with 
water,  the  amylo  acetic  ether  is  truly  etherial  in  its  nature. 

4027.  By  the  substitution  of  two  atoms  of  oxygen  for  a 
like  number  of  hydrogen,  effected  by  treating  potato  spirit 
with  hydrate  of  potash,  a  change  in  composition  arises 
analogous  to  that  by  which  alcohol  is  converted  into  acetic 
acid.     An  acid  is  in  this  way  created,  called  valerianic,  in 
consequence  of  its  being  identical  in  properties  and  com- 
position with  that  extricated  by  distilling  water  from  the 
root  of  valerian. 

4028.  This  acid  was  produced,  also,  by  causing  potato 
spirit  to  fall  slowly  in  successive  drops   upon    platinum 
black  duly  heated.     Peculiar  liquids,  somewhat  etherial  in 
their  properties,  have  been  evolved  from  potato  spirit,  of 
which  the  one  C20  H17  Cl3  O2  seems  to  be  a  congener  with 
chloral,  the  other  with  olefiant  gas  the  hydruret  of  carbon 
of  Liebig. 

Glyceryl,  C6  H7. 

4029.  The  wonderful  fabric  of  scientific  knowledge  for 
which  we  are  indebted  to  the  skill,  sagacity  and  ingenuity 
of  modern  chemists,  is  formed  in  part  of  materials  which 
are  altogether  new,  and  in  part  of  such,  as  although  long 
known,  owe  nearly  all  their  present  theoretic  value  to  the 


OF  GLYCERINE.  397 

part  which  they  have  latterly  been  made  to  answer  in  the 
great  fabric  to  which  I  have  alluded. 

4030.  In  the  preceding  account  of  the  amyl  series  it 
may  be  noticed,  that  a  liquid  long  since  distinguished  by 
Scheele,  and  known  under  the  name  of  oil  of  potato  spirit 
or  oil  of  potatoes,  has  latterly  been  dignified  with  a  place 
among  the  congeners  of  alcohol. 

4031.  In  glycerine,  C6  H7  O5  +  HO,  the  hydrated  oxide 
of  the  compound  radical  glyceryl,  we  find,  in  like  manner, 
a  compound  of  similar  antiquity,  and,  as  respects  its  dis- 
coverer, of  like  origin ;  having  been  well  known  since  the 
time  of  Scheele,  as  the  sweet  principle  of  oils.     For  the 
rank  which  it  now  occupies,  the  scientific  world  is  indebted 
to  Chevreul  and  Pelouze. 

4032.  Anterior  to  the  labours  of  Chevreul,  an  erroneous 
notion  existed  that  the  process  of  saponification  consisted 
in  nothing  more  than  a  union  between  the  alkali  and  oil; 
so  that  it  was  deemed  to  be  a  case  simply  of  combination. 
The  existence  in  every  oil  of  an  electro-negative,  and  an 
electro-positive  ingredient,  the  one  performing  the  part  of 
a  base,  the  other  of  an  acid,  was  not  imagined. 

4033.  The  oxide  of  glyceryl  is  the  base  common  to  a 
majority  of  vegetable  and  animal  fixed  oils,  whether  liquid 
or  the  solid  state,  denominated  fat,  being  liberated  during 
the  boiling  of  those  substances  with  fixed  alkalies,  as  in 
the  process  of  saponification.    It  is  best  prepared  by  sapo- 
nifying oil  of  olives  with  litharge,  separating  the  resulting 
solution  of  glycerine,  and  precipitating  any  dissolved  lead 
by  sulphydric  acid  (897,  899). 

4034.  Glycerine  is  said  to  be  deficient  of  two  properties 
belonging  to  its  alcoholic  congeners,  solubility  in  ether, 
and  susceptibility  of  distillation  without  decomposition.    It 
is  sweet,  colourless,  and  inflammable;  of  the  density  of 
1.252,  being  about  one-fourth  heavier  than  water. 

4035.  It  does  not  appear  that  there  are  any  other  im- 
portant compounds  formed  with  this  radical  by  the  basaci- 
gen  bodies  or  the  acids,  so  as  to  be  productive  of  com- 
pounds congeneric  with  those  so  formed  by  most  of  the 
other  etherefiable  compound  radicals.     There  is,  neverthe- 
less, a  congener  of  sulphovinic  acid  in  sulphoglyceric  acid, 
more  properly  called  the  double  sulphate  of  the  oxides  of 
glyceryl,  and  of  hydrogen. 


398  ORGANIC  CHEMISTRY. 

Cetyl,  C32  H33. 

4036.  Of  cetyl  it  may  be  sufficient  to  say,  that  it  is  per- 
fectly analogous  as  respects  the  part  which  it  performs  in 
spermaceti,  with  that  performed  by  glyceryl,  as  the  radi- 
cal in  the  base  of  the  fixed  oils  generally. 

4037.  The  diversity  of  such  oils,  in  other  cases,  is  pro- 
duced by  variation  in  the  acids  with  which  the  oxide  of 
glyceryl  in  them  severally  is  combined.     Spermaceti  has 
been  represented  as  a  solitary  instance  in  which  a  change 
of  properties  results  in  a  concrete  fixed  oil,  from  a  pecu- 
liarity in  the  hydrated  oxide  constituting  the  base,  while 
the  acids,  combined  with  this  base,  are  those  which  have 
been  described  as  entering  into  the  composition  of  oleagi- 
nous products  in  general.     Recently,  this  view  of  the  sub- 
ject has  been  controverted  by  Smith.     Silliman's  Journal, 
October,  1842.     (See  5055,  page  426.) 

4038.  The  hydrated  oxide  of  cetyl,  C32  H33O  +  HO,  may 
be  elaborated  from  spermaceti  by  saponification,  in  a  mode 
resembling  that  by  which  glycerine  is  obtained.     It  has 
been  designated  by  the  name  ethal,  a  word  made  up  of  the 
initials  of  alcohol  and  ether.     It  differs  from  other  alco- 
holic hydrated  oxides,  in  being  deficient  of  that  solubility 
in  water  which  is  one  of  the  most  striking  and  distinguish- 
ing attributes  of  alcohol  proper.     It  differs  also  in  being 
solid  until  heated  to  118°.     The  analogy  with  glycerine 
fails  as  respects  taste,  being  insipid;  also  in  this,  that  gly- 
cerine is  soluble  in  water,  and  insoluble  in  ether. 

4039.  Cetyl  has  not  been  isolated;  but  by  repeated  dis- 
tillation with  anhydrous  phosphoric  acid,  ethal  has  been 
made  to  yield  an  inflammable  liquid  compound,  C32  H32, 
having  to  it  a  relation  analogous  to  that  which  etherine  or 
etherole,  C4  H4,  has  to  ethyl,  C4  H5.    Cetene,  as  this  liquid 
is  called,  seems  to  be  of  the  nature  of  an  essential  oil,  since 
it  may  be  distilled.     It  requires,  however,  the  high  tempe- 
rature of  527°  for  this  purpose. 

4040.  Cetyl  coincides  in  habitudes  with  the  other  com- 
pound radicals  of  this  class,  as  respects  the  formation  of 
double  sulphates,  analogous  to  the  sulphovinates.     It  also 
forms  a  chloride  capable  of  being  distilled,  and  by  the  sub- 
stitution of  three  atoms  of  oxygen  for  two  of  hydrogen,  is 
converted  into  an  acid,  denominated  ethalic,  C32  H31  O3, 
which  is  a  congener  of  acetic  acid. 


OF  GUM.  399 

OF  NUTRITIOUS  VEGETABLE  SUBSTANCES  DEVOID  OF 
NITROGEN. 

4041.  Under  this  head  I  place  gum,  sugar,  fecula,  and 
lignin.  Immediately,  this  last  mentioned  substance  is  rather 
food  for  worms  than  for  man;  but  it  will  be  seen  that  lig- 
nin may  be  converted  into  sugar. 

4042.  The  substances  above  enumerated  might  be  treat- 
ed as  hydrates  of  carbon,  agreeably  to  the  suggestion  of 
Prout  (2096),  were  it  not  that  their  properties  do  not  war- 
rant the  idea,  that  the  hydrogen  and  oxygen  are  more  in- 
timately allied  to  each  other,  than  to  the  carbon. 

Of  Gum. 

4043.  Substances  known  under  the  generic  name  at  the 
head  of  this  article  have  certain  properties  in  common,  but 
vary  with  the  tree  by  which  they  are  generated.     Some, 
like  gum  arabic,  or  gum  Senegal,  are  perfectly  soluble  in 
water;  while  others,  like  tragacanth,  are  capable  only  of 
forming  a  paste  with  the  same  liquid.     Those  of  the  first 
mentioned  kind  are  susceptible  of  rapid  desiccation  and 
induration,  by  access  of  atmospheric  air,  while  the  others 
give  up  water,  comparatively,  with  reluctance.     They  are 
all  distinguished  from  resins,  which  they  resemble  exter- 
nally, in  being  insoluble  in  alcohol,  ether,  or  essential  oils. 
They  differ  from  sugar  in  the  want  of  sweetness,  and  from 
starch  in  not  being  coagulable  by  heat. 

4044.  Guerin,  in  an  elaborate  treatise  on  gums,  divides 
them  into  three  classes: — 1.  Arabin,  of  which  gum  arabic 
is  the  type,  soluble  in  cold  water.     2.  Bassorin,  which 
swells  into  a  jelly,  but  does  not  dissolve  in  water:  gum 
bassora,  or  tragacanth,  may  exemplify  this  class.     3.  Ce- 
rasin, from  the  gum  of  the  cherry-tree.     Cerasin  is  also 
insoluble  in  cold,  but  soluble  in  boiling  water,  and  when 
treated  with  nitric  acid,  gives  about  one-fourth  less  mucic 
acid  than  bassorin. 

4045.  Of  arabin,  by  his  analysis,  the  formula  is  C6  H5  O5. 
Gum  Senegal,  and  the  soluble  parts  of  gum  tragacanth  and 
bassora  gum,  consist  of  arabin. 

4046.  Of  bassorin  the  formula  is  C10  H11  O11. 

4047.  Cerasin  appears  to  be  metamorphic  arabin;  for  it 
has  precisely  the  same  composition,  and  is  changed  into 
it  by  solution  in  boiling  water.     The  gums  of  the  cherry, 
apricot,  prune,  peach,  and  almond  tree,  are  of  this  kind. 


400  ORGANIC  CHEMISTRY. 

4048.  Berzelius  employs  the  word  mucilage  to  desig- 
nate that  species  of  matter  which  is  exemplified  by  the 
bassorin  of  Guerin.     Varieties  of  this  kind  of  gum  are 
seen  in  infusions  of  flaxseed,  of  slippery  elm,  and  pith  of 
sassafras.    This  use  of  these  terms  is  not  adopted  by  Tur- 
ner, Kane,  or  Graham.     The  principal  difference  between 
gum  and  mucilage,  agreeably  to  general  acceptation,  seems 
to  be,  that  mucilage  is  not  susceptible  of  spontaneous  har- 
dening by  desiccation.    Graham  admits  only  of  two  genera 
of  gums,  exemplified  by  gum  arabic  and  gum  tragacanth. 
By  Kane,  they  are  treated  of  under  three  heads — arabin, 
cerasin,  and  dextrine,  or  artificial  gum.     This  last  men- 
tioned variety  is  obtained  from  starch,  and  does  not  ap- 
pear to  have  higher  pretensions  to  be  ranked  as  a  gum, 
than  the  modification  of  starch  by  heat,  known  as  British 
gum.     Substances  which  come  under  the  name  of  gum, 
agree  in  general  properties ;  yet  there  are  scarcely  any 
two  which  are  quite  similar.     Gum  arabic  is  deemed  to  be 
the  most  perfect  specimen  of  the  substances  bearing  this 
name. 

4049.  Berzelius  considers  the  reaction  of  a  solution  of 
this  substance  with  a  solution  of  the  silicate  of  potash,  as 
the  most  striking  characteristic  of  its  properties.     One 
portion  of  it  forms,  with  one  part  of  the  alkali  and  all  the 
acid,  a  triple  compound,  which  precipitates ;  while  another 
portion  of  the  gum,  and  the  remainder  of  the  potash,  com- 
bine and  remain  in  solution. 

4050.  Gum  arabic  differs  from  other  gums  in  combining 
with  the  sesquioxide  of  iron,  and  forming  a  compound  in- 
soluble in  water,  but  soluble  in  acids.     A  solution  of  gum 
arabic  in  1000  parts  of  water,  being  mixed  with  a  solution 
of  the  sesquioxide  of  iron,  yields,  in  24  hours,  a  yellow 
precipitate.     This  species  of  gum  also  combines  with,  and 
precipitates  the  protoxide  of  mercury  from  the  nitrate. 
There  appears  to  be  no  important  difference  between  gum 
Senegal  and  gum  arabic. 

Of  Sugars* 

4051.  Under  this  head  I  would  place  two  genera  of  sub- 
stances;   crystallizable  sugars,  and  syrups   incapable  of 

*  Liebig  treats  of  sugars  under  the  general  head  of  an  "  appendix  to  the  combina- 
tions of  ethyl  and  acetyl."  His  commentator,  Gregory,  alleges  that  they  are  "thus 
treated  of,  since  from  them  are  derived  all  the  compounds  of  ethyl;  and,  also,  be- 


OF  SUGARS.  401 

crystallization,  and  which  might  be  called  suavin.  Of  the 
former,  sugar  candy,  and  the  crystals  found  in  raisins  and 
honey,  are  specimens.  The  latter  are  exemplified  by  the 
uncrystallizable  syrups  of  raisins  and  of  honey;  also  the 
sweet  matter  of  the  sweet  potato,  and  the  uncrystallizable 
syrup  of  the  sugar  cane,  known  as  molasses. 

4052.  The  qualities,  both  of  crystallizable  and  uncrys- 
tallizable sugars,  vary  with  the  plants  from  which  they 
are  produced.     In  the  power  of  imparting  sweetness  to 
infusions,  the  crystallizable  sugar  of  the  cane  is  pre-emi- 
nent. 

4053.  As  sugar  has  been  found  to  be  very  susceptible 
of  yielding  alcohol  by  fermentation,  this  property  has  been 
made  the  basis  of  defining  the  meaning  of  the  word,  so 
that  every  substance  capable  of  the  process  alluded  to,  is 
to  be  considered  as  sugar,  whatever  may  be  its  taste,  or 
however  it  may  differ  in  its  properties  from  the  substances 
usually  called  by  the  name. 

4054.  Thus   the   fermentable   "wort"   of  distillers   or 
brewers,  the  uncrystallizable  juices  of  fruits,  a  substance 
found  in  mushrooms  or  ergot,  also  an  insipid  matter  found 
by  Thenard  in  diabetic  urine,  are  all  to  be  considered  as 
consisting  of  sugar,  so  far  as  they  are  capable  of  yielding 
alcohol  by  fermentation. 

4055.  I  am  reluctant  to  employ  words  in  a  sense  dif- 
ferent from  that  in  which  they  are  generally  understood. 
Agreeably  to  usual  acceptation,  sweetness  is  an  indispen- 
sable attribute  of  sugar.     Sugary  and  sweet  are  synony- 
mous.    "  As  sweet  as  sugar"  has  long  been  an  expression 
conveying  the  idea  of  superlative  sweetness. 

4056.  Chemists  have  erred,  I  think,  in  assuming  that 

cause  the  uncertainty  in  which  we  are  as  to  their  true  constitution,  renders  it  im- 
possible to  arrange  them  on  scientific  principles." 

That  ethyl  compounds  are  derived  from  sugars,  might  be  a  reason  for  treating  of 
them  under  sugars ;  but  I  cannot  perceive  the  converse  to  be  true.  But  as  aldehy- 
dous  or  acetous  acid,  and  acetic  acid,  are  placed  under  the  head  of  acetyl,  and  the 
compounds  of  mesityl  are  derived  from  acetic  acid,  a  compound  not  necessarily  de- 
rived from  sugar,  if  the  reason  above  given  were  sufficient  for  placing  sugars  under 
ethyl,  it  is,  on  that  same  ground,  improper  to  place  them  under  acetyl,  since  this  ra- 
dical is  not  necessarily  a  product  of  sugar. 

In  reply  to  the  last  sentence  quoted,  it  might  be  demanded,  why  inability  to  ar- 
range sugars  upon  scientific  principles,  justifies  their  being  placed  under  the  head 
selected,  in  preference  to  any  other:  whether  every  set  of  substances  which  cannot 
be  arranged  on  scientific  principles,  are  to  be  discussed  under  the  joint  head  of  com- 
binations of  ethyl  and  acetyl? 

The  best  justification  which  occurs  to  me  for  any  connexion  between  cane  sugar 
and  acetyl  is,  that  when  anhydrous  it  is  isomeric  with  acetyl,  one  atom  containing 
three  of  this  radical,  acetyl,  &  R*  -f-  3  =s  C«  H»  O^. 


402  ORGANIC  CHEMISTRY. 

nothing  besides  sugar  is  susceptible  of  the  vinous  fermen- 
tation. The  conversion  into  alcohol  of  the  insipid  product 
of  diabetes,  which  has  been  treated  as  sugar,  because 
proved  to  be  susceptible  of  the  process  in  question,  might 
with  more  propriety,  as  I  conceive,  be  deemed  to  demon- 
strate that  this  process  may  be  undergone  by  substances 
which  are  not  sufficiently  of  a  saccharine  nature  to  merit 
the  name  of  sugar. 

4057.  According  to  Kane,  after  cane  sugar  has  been 
subjected  to  a  ferment,  at  a  certain  time  before  its  conver- 
sion into  alcohol,  it  affects  polarized  light  in  the  same  way 
as  grape  sugar.     Hence  it  is  inferred,  that  cane  sugar  is 
not  directly  susceptible  of  the  vinous  fermentation;  and 
that  of  all   sugars,   that  of  the   grape   only  is  capable 
of  immediately  undergoing  that  process.     It  follows,  that 
if  the  contested  definition  be  not  disregarded,  the  sweet 
crystallizable   matter  extracted   from  the  cane,   hitherto 
considered  as  the  most  perfect  of  the  sugars,  must  be  de- 
prived of  its  title,  and  occupy  a  place  on  a  level  with 
starch,  as  being,  like  this  substance,  incapable  of  the  vi- 
nous fermentation,  without  a  previous  transformation  into 
grape  sugar. 

4058.  Liebig  enumerates  the  following  varieties  of  su- 
gar.    Cane  sugar*  grape  sugar,  lactin  or  sugar  of  milk,  un- 
crystallizable  sugar,  and  sugar  of  mushrooms.     To  these 
Graham  adds,  insipid  diabetic  sugar,  manna  sugar  or  man- 
nite,  and  liquorice. 

4059.  As  a  good  account  of  the  sources  of  the  sugar  of 
commerce,  and  the  means  by  which  it  is  elaborated  may 
be  found  in  the  United  States'  Dispensatory,  it  will  be 
doubly  inexpedient  to  extend  in  this  treatise  the  informa- 
tion given,  beyond  its  chemical  composition  and  habitudes. 

4060.  Of  cane  sugar,  perfect  specimens  are  seen  in  the 
best  double  refined  sugar,  and  in  colourless  sugar  candy. 
Its  specific  gravity  is  1.6.     At  350°  it  fuses  into  the  well 
known  form  of  barley  sugar,  which,  by  exposure  to  air,  is 
alleged  to  become  white,  opaque,  and  crystalline. 

4061.  Exposed  to  the  temperature  of  650°,  by  losiirg  an 
atom  of  water  besides  that  of  crystallization,  sugar  is 
transformed  into  the  dark  brown  substance  called  caramel. 
Thus  obtained,  caramel  is  not  entirely  exempt  from  unde- 
composed  sugar  and  other  impurities,  but  may  be  freed 
from  them  by  solution  in  water,  and  precipitation  by  alco- 


OF  GRAPE  SUGAR.  403 

hoL  The  precipitate  thus  created,  when  dried,  forms  a 
black  or  dark  brown  powder,  which  may  be  redissolved  in 
water.  It  is  insipid,  not  fermentable,  and  neither  acid  nor 
alkaline.  Caramel  is  used  to  deepen  the  colour  of  fer- 
mented or  spirituous  liquors.  During  its  decomposition 
by  heat,  fumes  are  emitted  by  sugar,  which  not  only  dis- 
guise, but,  as  I  believe,  neutralize  fetid  emanations.  For 
its  solution,  cane  sugar  requires  one-third  of  its  weight  of 
cold  water,  but  the  effect  of  this  liquid  at  a  high  tempera- 
ture, is  rather  that  of  lowering  the  point  of  fusion,  than 
acting  as  a  solvent;  since,  at  the  temperature  of  350°,  su- 
gar liquefies  per  se,  and  of  course  may  liquefy  with  the  mi- 
nutest proportion  of  water  which  can  be  added.  Hence 
the  liquefaction  is  due  to  heat  rather  than  to  water. 

4062.  If  a  concentrated  solution  of  sugar  be  subjected, 
for  some  time,  to  the  temperature  requisite  to  vaporize  the 
excess  of  water,  under  the  whole  pressure  of  the  atmos- 
phere, it  is  changed  by  degrees  into  uncrystallizable  sugar. 
Hence,  of  late  years,  the  vaporization  is  aided  by  a  reduc- 
tion of  atmospheric  pressure,  by  means  of  an  air  pump. 
(172.) 

4063.  Sugar  combines  with  some  salts;  and  acts  feebly 
as  an  acid,  so  far  as  to  unite  with  some  bases.     In  the 
insoluble  compound,  formed  by  anhydrous  sugar  with  oxi- 
dized lead,  the  base  is  a  dioxide.    With  one  atom  of  ba- 
ryta, sugar  forms  a  crystalline  compound;  with  common 
salt  it  forms  crystals  readily  soluble  in  water. 

4064.  Berzelius  alleges  that  an  aqueous  solution  of  su- 
gar  dissolves   the  carbonate  and   subacetate  of  copper, 
giving  rise  to  a  green  liquid,  from  which  the  metal  is  pre- 
cipitated by  sulphydric  acid,  or  cyanoferrite  of  potassium, 
but  not  by  alkalies.     When  boiled  with  solutions  of  cu- 
preous salts,  it  causes  the  reduction  of  the  copper. 

4065.  Several  products  are  obtained  by  the  reaction  of 
various  acids,  either  dilute  or  concentrated,  with  the  various 
kinds  of  sugar;  also  by  their  reaction  with  alkalies.    These 
products  being  complicated  in  their  nature  and  of  little 
practical  utility,  I  shall  not  treat  of  them  here. 

Grape  Sugar. 
Crystallized,  C12  H14  O14;  Anhydrous,  C  M  H12  O12. 

4066.  Crystals  of  this  sugar  may  be  seen  in  raisins,  in 
what  are  called  candied  sweetmeats,  and  in  honey,  in  either 

52 


404  ORGANIC  CHEMISTRY. 

of  which  it  forms  the  least  fluid  portion.  Fruits  generally 
owe  their  sweetness  to  its  presence.  The  sugar  formed 
from  starch  by  digestion  with  diastase,  or  sulphuric  acid, 
is  of  this  species;  and  also  the  sugar  of  diabetes.* 

4067.  Grape  sugar  may  be  obtained  in  crystals  from 
grape  juice,  by  neutralization  with  chalk,  clarifying  with 
albumen,  evaporation,  and  subsequent  repose:  also  from 
diabetic  urine,  by  evaporation  to  dryness,  by  means  of  a 
water  bath,  washing  the  resulting  crystalline  mass  on  a 
filter  with  cold  alcohol  until  it  becomes  white,  and  repeated 
re-solution  and  recrystallization. 

4068.  It  is  remarkable,  that  notwithstanding  the  ana- 
logy between  cane  and  grape  sugar,  they  differ  much  in 
their  chemical  qualities,  as  shown  by  their  habitudes  with 
chemical  reagents.     Strong   mineral   acids,  which  react 
but  feebly  with  grape  sugar^  readily  decompose  cane  su- 
gar.    With  alkalies  an  opposite  result  ensues.     The  com- 
pounds which  are  formed  by  these  sugars  respectively,  with 
bases,  are  quite  different. 

4069.  From  an  alcoholic  solution,  grape  sugar  crystal- 
lizes in  transparent  square  tables  or  cubes;  from  an  aque- 
ous solution,  it  consolidates  into  a  spongy  mass  of  crys- 
talline grains.t 

Sugar  of  Milk,  or  Lactin. 

4070.  The  formula  of  crystallized  sugar  of  milk  is  C24 
H24  O24,  or  C24  H19  O19  +  5HO.     By  a  heat  of  248°  it  loses 
two  atoms  of  water,  and  by  302°,  five  atoms.  (Berzelius.) 
It  is  obtained  by  evaporating  the  whey  of  milk,  and  puri- 
fying the  first  crystalline  product  by  animal  charcoal  and 
recrystallization.     It  forms  white,  semi-transparent,  quad- 
rangular prisms,  which  have  the  density  1.543.     They  are 
soluble  in  five  or  six  parts  of  cold  water,  and  in  two  and 
a  half  parts  of  boiling  water.     The  taste  of  the  crystals  is 
very  feeble,  being  inferior,  in  sweetness,  to  that  of  their 
solution.     Sugar  of  milk  is  unalterable  in  the  air,  or  by  a 
heat  under  212°,  and  is  insoluble   in  alcohol  or  ether. 
When  milk  is  exposed  to  a  temperature  of  from  95°  to 

*  Dumas  has  proposed  that  grape  sugar  be  called  glucose;  but  as  Liebig  alleges 
that  all  sugars,  even  that  of  the  cane,  have  to  be  converted  into  grape  sugar  in  order 
to  be  rendered  susceptible  of  the  vinous  fermentation;  it  would  seem,  consistently 
with  the  received  definition  of  sugar  (4053),  as  if  cane  sugar  should  be  called  glu- 
cose, yielding  the  name  of  sugar  to  the  sweet  matter  of  the  grape. 

t  See  fermentation;  also  (4071). 


OF  MUSHROOM  SUGAR,  &C.  405 

104°,  it  undergoes  the  vinous  fermentation,  generating  al- 
cohol, while  its  sugar  disappears.  But  it  is  presumed  that 
the  latter  is  converted  first  into  grape  sugar,  probably 
under  the  influence  of  the  free  acid,  which,  being  formed, 
curdles  the  milk.  Milk  sugar  forms  two  compounds  with 
oxide  of  lead,  of  which  the  formulae  are  C24  H19  O19  +  5PbO, 
and  C24  H19  O19  +  lOPbO.  (Berzelius.) 

Mushroom  Sugar. 

4071.  This  sugar,  of  which  the  formula  is  CJ2  H13  O13, 
according  to  an  analysis  by  MM.  Liebig  and  Pelouze, 
was  obtained  by  M.  Wiggers,  by  subjecting  the  tincture 
of  the  ergot  of  rye  to  water.     It  is  crystallizable  and  solu- 
ble in  water  and  alcohol,  but  insoluble  in  ether.     Mush- 
room sugar  is  also  fermentable  by  yeast,  and  diffuses  the 
odour  of  caramel  when  carbonized  by  a  high  temperature. 
The  only  property  by  which  this  sugar  is  distinguished 
from  the  ordinary  species  is,  that  it  does  not  throw  down 
sub-oxide  of  copper  from  a  boiling  solution  of  the  acetate. 

Of  the  Fermentable  Matter  of  Diabetes,  called  Insipid  Sugar. 

4072.  It  has  been  stated  (4052),  that  a  substance  was 
obtained,  by  Thenard,  from  the  urine  of  diabetes  insipidus, 
and,  subsequently,  by  Bouchardat,  from  the  same  source, 
which  was  insipid,  or  only  faintly  sweet.     The  aqueous 
solution  of  this  sugar  was  fermentable  by  yeast,  and  sus- 
ceptible of  being  converted  into  the  sugar  of  grapes  by  di- 
lute sulphuric  acid. 

Liquorice  Sugar. 

4073.  The  inspissated  juice  of  the  root  of  the  Glycyr- 
rhiza  glabra  contains  a  species  of  unfermentable  sugar, 
which  may  be  obtained  by  clarifying  the  juice  with  albu- 
men, precipitating  the  sugar  with  sulphuric  acid,  washing 
the  precipitate  with  water,  dissolving  it  in  alcohol,  which 
separates    some  undissolved   albumen,  and  then  decom- 
posing the  sulphate  of  liquorice  sugar  by  carbonate  of  pot- 
ash.    After  evaporation,  the  sugar  remains  as  a  yellow 
translucent  mass,  cracked  in  all  directions,  and  easily  de- 
tached from  the  vessel  in  which  it  has  been  desiccated. 
Liquorice  sugar  is  capable  of  forming  soluble  or  sparingly 
soluble  compounds,  with  both  the  mineral  and  vegetable 
acids.     It  also  combines  with  bases. 


406  ORGANIC  CHEMISTRY. 

Manna  Sugar,  or  Mannite. 

4074.  The  formula  of  manna  sugar  is  C6  H7  O6,  accord- 
ing to  the  analysis  of  Oppermann  and  of  Liebig.     Manna 
is  in  oblong  globules  or  masses,  of  a  yellowish-white  co- 
lour, being  an  exudation  from  various  trees,  principally  the 
fraxinus  ornus,  and  encalyptus  mannifera  of  New  South 
Wales.     It  exists  also  in  the  juices  exuded  by  cherry  and 
plum  trees,  in  those  of  various  kinds  of  mushrooms,  and 
of  celery  and  other  roots.     Manna  sugar  may  be  prepared 
by  dissolving  the  manna  of  the  shops  in  boiling  alcohol, 
and  allowing  the  solution  to  cool.     It  may  be  purified  by 
repeated  crystallizations.     Mannite  crystallizes  in  slender, 
colourless,  four-sided  prisms,  of  an  oily  lustre.     It  has  a 
slightly  sweet  taste,  forms,  with  water,  a  solution  which  is 
not  fermentable.     It  is  anhydrous,  and  may  consequently 
be  heated  to  redness,  without  any  loss  of  weight.     Its 
aqueous  solution  dissolves  oxide  of  lead.     Nitric  acid  con- 
verts mannite  either  into  oxalic,  or  saccharic  acid;  but  not 
into  mucic  acid.     Mannite  is  also  one  of  the  products  of 
the  vinous  fermentation  of  cane,  or  grape  sugar.1* 

Fecula,  or  Starch. 

4075.  A  substance,  of  which  starch  is  a  good  specimen, 
and  of  which  the  generic  name  is  fecula,  may  be  obtained 
from  the  rneal  or  flour  of  grain,  and  from  the  tubers  of  the 
potato,  and  various  other  vegetables.     It  is  found  in  com- 
merce under  the  names  of  sago,  tapioca,  arrow-root,  &c. 
Of  the  sources  of  these  varieties  of  fecula,  an  excellent  ac- 
count is  given  in  the  United  States  Dispensatory.     It  is 
more  or  less  a  constituent  of  vegetables  in  general.    When 
the  farinaceous  matter,  procured  from  such  sources  by 
rasping  or  grinding,  is  washed,  the  fecula  is  suspended, 
and  subsequently  deposited.   Where  there  is  vegeto-animal 
matter,  as  in  wheat  flour,  fermentation  is  employed  to  get 
rid  of  this  substance. 

4076.  It  was  discovered  by  Leeuwenhoeck,  with  the  aid 
of  a  microscope,  in  1716,  that  starch  consists  of  globular 

trains,  each  enveloped  in  a  tegument,  pocket,  or  sac,  dif- 
jring  from  the  internal  mass.     In  1825,  these  observa- 
tions were  confirmed  and  extended  by  Raspail,  who  also 

*  Graham,  page  757. 


OF  DIASTASE.  407 

observed  that  the  envelope,  or  tegument,  was  insoluble  in 
water,  while  the  interior  portion  was  soluble  in  this  liquid. 
Agreeably  to  the  microscopic  observations  of  this  last 
mentioned  author,  the  sizes  of  the  globules  of  fecula  vary 
with  the  plant  whence  it  may  be  derived.  Those  of  the 
potato  did  not  exceed  in  diameter  ws  of  an  inch;  those  of 
wheat  2T7  of  an  inch;  and  of  arrow-root  TGV.  As,  accord- 
ing to  Payen  and  Persoz,  the  tegument  does  not  form  more 
than  four  or  five  thousandths  of  the  weight,  the  internal 
portion  may  be  considered  as  characterizing  the  whole, 
uninfluenced  to  any  important  extent  by  the  tegumentary 
matter. 

4077.  Fecula  is  blackened  by  a  certain  quantity  of  io- 
dine, becomes  blue  with  less,  and  violet  with  still  less. 
The  iodide  of  starch  becomes  colourless  at  a  temperature 
less  than  200°,  and  if  not  made  to  reach  the  boiling  point, 
regains  its  colour  on  cooling. 

4078.  Starch  does  not  combine  with  cold  water,  but 
forms  a  viscid  solution  with  hot  water.     It  is  neither  dis- 
solved nor  acted  upon  by  alcohol  or  ether. 

4079.  Fecula  dissolves  in  nitric  acid  without  heat,  and 
when  heated  with  it  is  converted  into  oxalic  acid.    A  slight 
torrefaction  changes  its  nature,  so  that  it  may  be  used  as 
a  substitute  for  gum.     Triturated  with  potash,  fecula  ac- 
quires the  property  of  dissolving  in  cold  water.     The  so- 
lution is  clouded  by  acids. 

4080.  Its  solution  in  hot  water  is  precipitated  by  sub- 
salts  of  lead,  and  in  cold  water  by  an  infusion  of  galls. 

s 

OF  DIASTASE, 

And  of  the  Conversion  of  Fecula  into  Dextrine  and  Grape 

Sugar. 

4081.  Boiled  in  water,  constantly  replenished  for  nearly 
forty  hours,  with  between  TV  and  Tihr  of  its  weight  of  sul- 
phuric acid,  fecula  is  converted  into  grape  sugar.    A  simi- 
lar change  is  alleged  to  have  ensued  partially  in  starch, 
which  was  made  into  a  paste  with  twelve  times  its  weight 
of  boiling  water,  and  kept  for  two  years.     By  the  addition 
of  the  glutinous  matter  obtained  by  washing  wheat  dough, 
and  the  application  of  a  heat  between  122°  and  167°  Fah., 
a  similar  result  is  said  to  have  been  attained  in  about  ten 
or  twelve  hours. 


408  ORGANIC  CHEMISTRY. 

4082.  It  is  well  known  to  those  who  are  acquainted  with 
the  manufacture  of  whiskey  from  grain,  that  a  portion  of 
malt  is  necessary  to  render  the  wash  or  wort  susceptible 
of  the  vinous  fermentation;  and  that  the  product  is  much 
affected  by  the  circumstances  under  which  the  infusion  of 
the  grain  is  accomplished.     Nearly  thirty  years  ago,  my 
late  friend,  Col.  Anderson,  who  had  distinguished  himself 
by  his  ingenuity  and  sagacity  in  improving  the  processes 
and  apparatus  of  our  American  distilleries,  expressed  to 
me  an  opinion,  that  the  mixture  of  farina  and  water  be- 
came sweeter  towards  the  close  of  the  process  of  infusion, 
and  that  he  believed  a  chemical  change  was  induced,  by 
which  more  or  less  sugar  was  generated.     The  inference 
of  our  ingenious  countryman  has  been  fully  justified  by  the 
researches  of  Payen  and  Persoz,  whence  it  appears  that, 
by  digestion  with  malt,  fecula  is  at  first  partially  changed 
into  a  sweetish  gummy  matter,  called  dextrine,  and  that 
this   matter   is   afterwards   converted   into   grape  sugar. 
Dextrine  has  received  its  name  from  a  peculiar  influence 
which  it  exercises  upon  the  plane  of  polarization,  during 
the  passage  of  light.*    It  may  be  considered  as  holding,  as 
respects  its  properties,  an  intermediate  position  between 
fecula  and  grape  sugar. 

4083.  The  sugar-producing  property  thus  existing  in 
malt,  has  been  traced  to  a  peculiar  principle  called  dias- 
tase, which  exists  therein  in  a  proportion  not  exceeding  a 
five-hundredth.     It  is  obtained  by  moistening  ground  malt 
with  half  its  weight  of  water,  and  exposing  the  mass  to 
pressure.     The  exuding  liquor  is  mingled  with  a  quantity 
of  alcohol  of  840°,  by  which  the  diastase  is  thrown  down 
impure.     By  three  successive  solutions  in  water,  and  pre- 
cipitations by  the  same  means,  with  subsequent  exposure 
on  a  glass  pane,  in  thin  layers,  to  a  current  of  air  about 

*  When  light,  polarized  by  reflection  from  the  surface  of  a  plate  of  black  glass,  or 
from  the  surm.ce  of  a  pile  of  superposed  plates  of  transparent  glass,  reaches  the  eye 
through  a  disc  of  tourmalin,  a  solution  of  dextrin  being  interposed  in  a  tube  between 
the  reflecting  plate  and  tourmalin,  the  light  does  not  disappear  in  those  positions  of  the 
tourmalin  in  which  light  would  be  completely  absorbed  without  the  interposition  of 
the  solution  of  dextrine ;  but  prismatic  colours  are  produced  which  follow  a  certain 
order,  if  the  plane  of  polarization  is  turned  from  left  to  right.  It  is  by  the  order  of 
these  colours,  that  a  liquid  is  said  to  polarize  light  to  the  right  or  to  the  left.  The 
solution  of  starch  polarizes  to  the  right,  and  that  of  dextrine  considerably  more  so  in 
the  same  direction ;  while  a  solution  of  cane  sugar  produces  the  succession  of  colours 
in  an  inverse  order,  and  is  said  therefore  to  polarize  to  the  left.  The  progress  of 
chemical  changes  may  thus  often  be  observed  in  a  solution  of  starch,  the  juices  of 
plants,  and  other  organic  fluids. —  Graham,  743. 


OF  LIGNIN.  409 

121°  Fah.,  pure  and  dry  diastase  is  obtained  in  the  state 
of  a  white  amorphous  solid  matter.  Diastase  does  not 
alter  gum,  sugar,  gluten,  nor  albumen,  nor  the  teguments 
of  fecula,  but  operates  surprisingly,  as  above  described,  on 
fecula  proper.  This  change  is  effected  without  any  ab- 
sorption of  the  air,  or  any  evolution  of  gaseous  matter.  It 
may  take  place  either  in  pleno  or  vacuo.  An  infusion  of 
100  parts  of  starch  in  39  parts  of  water,  at  about  90°  Fah., 
being  mixed  with  6.13  parts  of  diastase,  dissolved  in  40 
parts  of  cold  water,  and  digested  afterwards  for  an  hour, 
at  a  temperature  between  90°  and  100°,  gave  86.91  parts 
of  sugar.  At  the  temperature  of  158°,  one  part  of  dias- 
tase will  convert  2000  parts  of  starch  into  sugar.* 

4084.  When  sulphuric  acid  is  employed  in  lieu  of  dias- 
tase, if,  by  confinement,  the  temperature  and  pressure  are 
raised  (192),  less  sulphuric  acid  will  suffice.     Less  time  is 
requisite  when  care  is  taken  to  prevent  too  rapid  refrige- 
ration. 

4085.  If  a  paste,  made  by  subjecting  starch  and  water 
to  ebullition,  be  gently  poured  into  a  boiling  dilute  solution 
of  sulphuric  acid,  the  pasty  consistency  soon  disappears. 
In  like  manner,  starch  paste  loses  its  gelatinous  character 
when  mingled  with  malt  wort,  and  if  kept  at  a  temperature 
between  190°  and  200°,  becomes,  at  the  end  of  some  hours, 
converted  into  grape  sugar. 

4086.  In  proportion  as  the  diastase    saccharifies   the 
starch,  it  disappears   itself;    and  when  the   solution   no 
longer  acts  on  a  fresh  portion  of  starch,  the  presence  of 
diastase  cannot  be  detected  in  it.     The  reaction  is  proba- 
bly chemico-electric,  and  if  understood,  would  throw  light 
on  a  multitude  of  phenomena. 

4087.  When  dried,  diastase  is  a  white,  solid,  amorphous 
substance,  soluble  in  water  and  in  weak  alcohol,  but  in- 
soluble in  absolute  alcohol.     It  is  not  known  to  enter  into 
combination  with  any  substance.t     It  received  its  name 
from  JWjj^,,  I  separate,  in  reference  to  separation  of  the 
envelope  of  the  starch  globules  (4065). 

Lignin. 

4088.  The  tasteless,  inodorous,  insoluble,  but  tenacious 
fibres  of  wood,  hemp,  cotton,  or  flax,  and  other  plants, 

*  Graham,  745.     Annales  de  Chimie  et  de  Physique,  Vol.  53,  p.  73. 
t  Gregory's  Turner,  943.     Graham,  744. 


410  ORGANIC  CHEMISTRY. 

have  been  deemed  to  consist  of  a  peculiar  vegetable  sub- 
stance, called  lignin,  from  lignum,  the  latin  for  wood.  The 
formula  of  lignin,  dried  between  300°  and  350°,  is  C12  H8  O8 
(Prout). 

4089.  Graham  alleges,  that  it  constitutes  about  95  per 
cent,  of  baked  wood,  and  that  it  may  be  obtained  in  purity 
by  treating  the  sawings  of  wood,  paper,  or  the  fibre  of  lint, 
cotton,  hemp,  &c.,  successively  with  ether,  alcohol,  water, 
diluted  acid,  and  a  caustic  alkaline  solution,  so  as  to  dis- 
solve and  remove  all  the  matter  soluble  in  those  menstruse. 
Wood  consists  of  an  association  of  capillary  tubes,  in 
which,  after  it  is  desiccated,  agreeably  to  the  observations 
of  Hartig,  a  quantity  of  starch  remains,  in  spherical  grains 
of  a  grey  colour.     Hence  by  triturating  it,  in  the  state  of 
fine  saw-dust,  with  water,  from  one-fourth  to  one-fifth  of 
its  weight  of  starch  may  be  obtained. 

4090.  If  Payen  is  to  be  credited,  wood  consists  of  two 
organic  principles,  one  of  which  is  isomeric  with  starch, 
having  the  same  formula,  C12  H10  O10,  being  named  cellu- 
lose by  him.    The  other  principle,  which  forms  the  tubes,  is 
considered  by  the  same  author  as  the  true  lignin.     Cellu- 
lose was  obtained  by  subjecting  sawings  of  beech  wood  to 
several  times  its  weight  of  the  most  concentrated  nitric 
acid,  which  leaves  that  principle,  while  it  dissolves  the  lig- 
nin.   Cellulose  is  dissolved  by  concentrated  sulphuric  acid 
without  blackening,  and  is  then  converted  into  dextrine. 
The  formula  of  lint,  hemp,  straw,  and  linen  cloth,  was 
found  by  Payen  to  be  C35  H24  O20.     Oak  wood,  by  the  ana- 
lysis of  Gay-Lussac  and  Thenard,  is  C36  H22  O22. 

4091.  When  hemp,  straw,  &c.,  are  added  cautiously  to 
concentrated  sulphuric  acid,  so  as  to  prevent  elevation  of 
temperature,  not  only  is  dextrine  created,  but  also  ligno- 
sulphuric  acid,  analogous  to  benzo-sulphuric  acid,  which 
forms  a  soluble  salt  with  baryta,  or  with  oxide  of  lead. 

4092.  The  dextrine  formed  when  lignin  is  dissolved  in 
sulphuric  acid,  is  converted,  by  dilution  and  boiling,  into 
starch  sugar. 

4093.  Saw-dust,  gum,  and  starch,  dissolve  in  the  most 
highly  concentrated  nitric  acid,  without  decomposing  the 
acid ;  and,  if  immediately  diluted  with  water,  give  a  white 
pulverulent  neutral  substance,  insoluble  in  water,  which 
contains  the  elements  of  nitric  acid,  and  is  highly  combus- 
tible. 


OF  VEGETO- ANIMAL  SUBSTANCES.  411 

4094.  To  obtain  grape  sugar  from  lignin,  twelve  parts 
of  shreds  of  paper  or  linen,  or  of  wood  shavings,  are  inti- 
mately incorporated  by  trituration  with  seventeen  parts 
of  concentrated  sulphuric  acid  (according  to  Vogel  five 
parts),  and  one  of  water,  carefully  preventing  any  rise  of 
temperature.    After  twenty-four  hours,  the  resulting  tarry 
mass  is  to  be  dissolved  in  water,  boiled  for  ten  hours,  neu- 
tralized with  chalk,  and  being  filtered  and  evaporated  to  a 
syrupy  consistence,  the  residue  is  to  be  left  to  crystallize. 

4095.  According  to  Brunner,  100  parts  of  fecula  yield 
100  of  crystallized  grape  sugar;  according  to  De  Saussure, 
110.     Agreeably  to  calculation,  100  of  fecula,  with  four 
atoms  of  water,  should  be  productive  of  120  of  sugar.    100 
parts  of  linen  shreds  produce  114  of  sugar,  according  to 
Bracconot;  or,  according  to  Guerin,  115  parts'. 

4096.  lit  is  worthy  of  remark,  that  the  formula  of  crys- 
tallized grape  sugar  may  be  made  by  adding  to  the  for- 
mula of  lignin  six  atoms  of  water;  to  that  of  starch,  four 
atoms;  to  that  of  cane  sugar,  three  atoms;  and  to  that  of 
sugar  of  milk,  two  atoms. 

Formula  of  lignin,  C12  H  8  O  8        Starch,  C13  H10  Oto 

Six  atoms  of  water,  H  6  O  6       Four  atoms  of  water,        H  4  O  * 


Crystallized  grape  sugar,  C13  H14  O14       Grape  sugar,  Cia  H14  O14 

Crystallized  cane  sugar,    C13  H11  O11       Sugar  of  milk,  C13  H13  O12 

Three  atoms  of  water,  H  3  O  3       Two  atoms  of  water,        H  3  O  a 


Grape  sugar,  C13  H14  O14       Grape  sugar,  C14  H14  O14 

OF  VEGETO-ANIMAL  SUBSTANCES. 

Under  this  Head  are  included  Gluten,  Vegetable  Albumen, 
Vegetable  Fibrin,  and  Legumen,  or  Vegetable  Caseine. 

4097.  Plants  contain  substances  which  have  been  desig- 
nated as  vegeto-animal,  on  account  of  their  analogy  with 
the  white  of  egg,  and  the  fibrin  of  animal  matter.     Nitro- 
gen is  always  an  ultimate  element  in  them,  and  occasion- 
ally sulphur  and  phosphorus.     As  they  are  to  be  found  in 
all  vegetables,  to  a  greater  or  less  extent,  it  appears  pro- 
per to  arrange  them  under  the  head  of  the  general  princi- 
ples of  vegetables. 

4098.  It  had  long  been  known  that  wheat  dough,  by 
being  enclosed  and  kneaded  within  a  porous  bag,  while 

53 


412  ORGANIC  CHEMISTRY. 

subjected  to  water,  might  be  resolved  into  a  portion  which 
would  be  washed  away  by  the  water,  and  an  adhesive  por- 
tion left  within  the  bag. 

4099.  Beccaria  first  drew  the  attention  of  chemists  to 
the  substance  thus  obtained.  Subsequently,  Rouelle,  Jr., 
demonstrated  the  existence  in  the  expressed  juices  of  many 
plants,  of  a  substance  coagulable  by  heat,  like  animal  albu- 
men. This  coagulable  matter  was,  by  Fourcroy,  deemed 
to  be  of  the  same  nature  as  the  albumen  of  eggs.  Subse- 
quently, Einhof  demonstrated  the  existence,  in  rye,  barley, 
peas,  and  beans,  of  two  vegeto-animal  substances;  one  re- 
sembling white  of  egg,  the  other,  which  he  designated  as 
gluten,  was  not  considered  as  resembling  any  animal  sub- 
stance. 

5000.  It  may  be  inferred,  from  the  account  of  gluten 
given  by  Berzelius,  that  both  Einhof  and  Taddei  subjected 
the  gluten  of  Beccaria  to  boiling  alcohol,  and  thus  resolved 
it  into  two  substances;  one  similar  to  albumen  in  its  pro- 
perties, the  other  soluble  in  alcohol,  especially  when  boil- 
ing, and  possessing,  in  a  high  degree,  the  adhesiveness  and 
other  properties  by  which  gluten  had  been  distinguished. 

5001.  The  matter  taken  up  by  the  boiling  alcohol  was, 
by  Taddei,  designated  as  gliadine,  from  yA<«,  glue,  the  por- 
tion  remaining   undissolved,    zimome,  from  £yfM7,  leaven. 
Berzelius  treats  the  matter,  soluble  in  alcohol,  as  gluten 
nearly  pure,  and  the  residue  as  vegetable  albumen,  and 
gives  the  following  account  of  the  sources  and  properties 
of  gluten  and  the  vegetable  albumen  with  which  it  is  as- 
sociated. 

Gluten. 

5002.  It  owes  its  name  to  the  adhesive  property  which 
it  possesses,  and  which  it  communicates  to  wheat  dough. 
It  exists  in  the  seed  of  the  grape,  and  of  the  cerealia  es- 
pecially; also  in  those  of  leguminous  plants,  such  as  peas 
and  beans,  in  which  it  is  found  in  combination  with  starch 
and  vegetable  albumen.     Its  distinguishing  characteristics 
are  as  follows.     When  isolated,  it  is  almost  insoluble  in 
water.     It  is  gluey  when  moist,  yellow  and  translucent 
when  dry.     Ordinarily,  it  has  an  acid  reaction  with  litmus, 
in  consequence  of  the  presence  of  acetic  and  phosphoric 
acid.     It  is  soluble  in  alcohol,  especially  when  boiling,  and 
likewise  in  diluted  aqueous  solutions  of  acids,  caustic  alka- 


OP  VEGETABLE  ALBUMEN.  413 

line  leys,  &c.  It  is  precipitated  from  the  latter  by  ferro- 
prussiate  of  potash.  With  nut-galls  it  gives  a  precipitate, 
which  is  not  redissolved  even  by  ebullition. 

N    Vegetable  Albumen. 

5003.  It  is  found  in  the  above  mentioned  seeds  in  com- 
bination with  gluten ;  in  seeds  which  yield  emulsions,  as, 
for  instance,  in  almonds;  and  likewise  in  the  seeds  of  the 
ricinus,  where  it  is  found  in  combination  with  an  oil.     It 
exists  in  all  vegetable  juices  which  coagulate  with  heat. 
Vegetable  albumen  is  soluble  in  water,  until  coagulated  by 
heat,  but  is  not  soluble  in  alcohol;  it  is  not  adhesive,  and 
by  desiccation  becomes  opaque,  and  of  either  a  white, 
gray,    brown,  or  black   colour.     It   dissolves   readily  in 
caustic  alkaline  solutions,  neutralizing  their  caustic  taste, 
and  is  precipitated  by  a  great  excess  of  acid.     The  pre- 
cipitate is  a  chemical  compound  of  albumen  with  the  acid, 
soluble  in  water  when  pure,  but  less  so  when  this  liquid  is 
acidulated. 

5004.  The  aqueous  solution  of  vegetable  albumen  is 
precipitated  by  acids,  by  ferro-prussiate  of  potash,  by  chlo- 
ride of  mercury,  and  infusion  of  galls;  being,  in  these  re- 
spects, perfectly  analogous  to  animal  albumen. 

5005.  Gluten  and  vegetable  albumen  spontaneously  un- 
dergo decomposition,  accompanied  by  an  evolution  of  am- 
monia, a  production  of  the  acetate  of  ammonia,  and  like- 
wise the  fetor  which  distinguishes  the  putrefaction  of  ani- 
mal substances.     At  a  certain  period  of  putrefaction,  they 
have,  whether  separate  or  mixed,  the  smell  of  old  cheese. 

Of  the  Gluten  and  Albumen  of  Wheat. 

5006.  If  we  make  a  thick  paste  of  wheat  with  water,  in 
a  porous  bag,  and  knead  this  paste  within  the  bag,  under 
water,  until  this  liquid  is  no  longer  rendered  milky,  there 
remains,  finally,  a  gray  coherent  elastic  residue.     This 
residue  consists  mainly  of  a  mixture  of  gluten  and  vegeta- 
ble albumen,  not  quite  free  from  other  matter  derived  from 
the  wheat,  and  more  or  less  of  starch,  which  it  is  difficult 
to  remove  completely.     This  residue  does  not  contain  the 
whole  of  the  vegeto-animal  matter  of  the  wheat,  a  part 
being  carried  away  by  the  water  during  the  kneading  of 
the  paste. 


414  ORGANIC  CHEMISTRY. 

5007.  To  separate  from  each  other  the  albumen  and 
gluten  proper,  contained  in  the  gluten  of  Beccaria,  it  is  ne- 
cessary to  subject  it  to  boiling  alcohol,  till  this  liquid,  on 
being  filtered,  is  not  made  turbid  by  cooling.    The  alcohol 
dissolves  the  gluten  proper,  as  well  as  another  substance 
imperfectly  known,  leaving  the  vegetable  albumen.     The 
gluten  is  obtained  by  mixing  the  alcoholic  solution  with 
the  water,  and  removing  the  alcohol  by  distillation.     A 
liquid  remains,  in  which  the  gluten  floats  in  coherent  volu- 
minous flocks.     A  very  small  portion  of  gluten  remains  in 
solution,  combined  with  gum. 

5008.  The  gluten  being  separated  from  the  liquid,  is  of 
a  pale  yellow,  and  readily  becomes  agglutinated  into  a 
mass,  which  sticks  to  the  fingers,  is  elastic,  insipid,  and 
endowed  with  a  peculiar  odour.     In  dry  air  it  becomes 
spontaneously  polished  on  the  outside,  and  of  a  deeper 
yellow,  drying,  by  little  and  little,  into  a  translucent  mass 
of  a  very  deep  yellow,  resembling  dried  animal  matter. 
Alcohol  dissolves  the  gluten,  and  the  solution,  which  is  of 
a  pale  yellow,  being  evaporated,  the  gluten  remains  in  the 
form  of  a  yellow  transparent  varnish.     If  the  gluten  be 
macerated  in  cold  alcohol,  it  is  whitened,  and  forms  a 
milky  solution,  from  which  an  insoluble  matter  is  depo- 
sited.    This  is  not  gluten,  though  of  a  kindred   nature, 
being  soluble  by  the  aid  of  ebullition;  the  resulting  solu- 
tion, when  concentrated,  acquires  a  mucilaginous  consist- 
ence on  cooling.    Gluten  dissolves  in  boiling  officinal  alco- 
hol, and  precipitates  by  refrigeration,  without  having  lost 
its  gluey  quality.     It  is  insoluble  in  ether,  or  in  fixed  oils 
or  volatile  oils.    If  we  subject  it  to  acetic  acid,  it  becomes, 
in  consistency,  mucilaginous,  semi-liquid,  losing  its  yellow 
colour.     Mixed  in  this  state  with  water,  it  gives  a  muci- 
laginous flocky  residuum  and  a  milky  solution. 

5009.  From  the  investigations  of  Einhof,  as  stated  by 
Berzelius,  it  appears   that  a   matter,  analogous  to  that 
above  described  as  true  gluten,  may  be  obtained  from  rye, 
barley,  oats,  or  even  from  maize,  which,  from  the  absence 
of  any  cohesiveness  in  its  moistened  meal,  would  not  be 
supposed  to  contain  any  matter  deserving  to  be  distin- 
guished as  gluten. 

5010.  It  will  be  perceived,  from  the  preceding  history  of 
the  opinions  and  observations  of  chemists,  respecting  the 
vegeto-animal  matter  obtained  from  wheat  and  the  seeds 


OF  THE  GLUTEN  AND  ALBUMEN  OF  WHEAT.      415 

of  other  vegetables,  that  the  idea  lately  put  forth  by  Lie- 
big,  respecting  the  identity  of  their  composition  with  ani- 
mal albumen,  has  long  been  entertained,  though  never  be- 
fore presented  so  forcibly  to  popular  attention. 

5011.  Respecting  the  matter  treated  as  gluten  by  Ber- 
zelius,  Liebig  advances  views  which  are  in  some  respects 
new,  and  somewhat  discordant.     I  will  here  quote  the  lan- 
guage of  the  author  last  mentioned: — 

"  These  nitrogenized  forms  of  nutriment  in  the  vegetable  kingdom  may  be  re- 
duced to  three  substances,  which  are  easily  distinguished  by  their  external  charac- 
ters. Two  of  them  are  soluble  in  water,  the  third  is  insoluble. 

"  When  the  newly-expressed  juices  of  vegetables  are  allowed  to  stand,  a  separa- 
tion takes  place  in  a  few  minutes.  A  gelatinous  precipitate,  commonly  of  a  green 
tinge,  is  deposited,  and  this,  when  acted  on  by  liquids  which  remove  the  colouring 
matter,  leaves  a  grayish  white  substance,  well  known  to  druggists  as  the  deposite 
from  vegetable  juices.  This  is  one  of  the  nitrogenized  compounds  which  serves  for 
the  nutrition  of  animals,  and  has  been  named  vegetable  fibrin.  The  juice  of  grapes 
is  especially  rich  in  this  constituent,  but  it  is  most  abundant  in  the  seeds  of  wheat, 
and  of  the  cerealia  generally.  It  may  be  obtained  from  wheat  flour  by  a  mechanical 
operation,  and  in  a  state  of  tolerable  purity;  it  is  then  called  gluten,  but  the  glu- 
tinous property  belongs,  not  to  vegetable  fibrin,  but  to  a  foreign  substance  present  in 
small  quantity,  which  is  not  found  in  the  other  cerealia. 

11  The  method  by  which  it  is  obtained,  sufficiently  proves  that  it  is  insoluble  in 
water;  although  we  cannot  doubt  that  it  was  originally  dissolved  in  the  vegetable 
juice,  from  which  it  afterwards  separated,  exactly  as  fibrin  does  from  blood. 

"The  second  nitrogenized  compound  remains  dissolved  in  the  juice  after  the  sepa- 
ration of  the  fibrin.  It  does  riot  separate  from  the  juice  at  the  ordinary  temperature, 
but  is  instantly  coagulated,  when  the  liquid  containing  it  is  heated  to  the  boiling 
point. 

"  When  the  clarified  juice  of  nutritious  vegetables,  such  as  cauliflower,  asparagus, 
mangel  wurtzel,  or  turnips,  is  made  to  boil,  a  coagulum  is  formed,  which  it  is  abso- 
lutely impossible  to  distinguish  from  the  substance  which  separates  as  coaarulum, 
when  the  serum  of  blood  or  the  white  of  an  egg,  diluted  with  water,  are  heated  to 
the  boiling  point.  This  is  vegetable  albumen.  It  is  found  in  the  greatest  abundance 
in  certain  seeds,  in  nuts,  almonds,  and  others,  in  which  the  starch  of  the  gramineae 
is  replaced  by  oil. 

"  The  third  nitroorenized  constituent  of  the  vegetable  food  of  animals  is  vegetable 
caseine.  It  is  chiefly  found  in  the  seeds  of  peas,  beans,  lentils,  and  similar  legu- 
minous seeds.  Like  vegetable  albumen,  it  is  soluble  in  water,  but  differs  from  it  in 
this,  that  its  solution  is  not  coagulated  by  heat.  When  the  solution  is  heated  or 
evaporated,  a  skin  forms  on  its  surface,  and  the  addition  of  an  acid  causes  a  coagu- 
lum, just  as  in  animal  milk. 

"These  three  nitrogenized  compounds,  vegetable  fibrin,  albumen,  and  caseine,  are 
the  true  nitrogenized  constituents  of  the  food  of  graminivorous  animals;  all  other  ni- 
trogenized compounds,  occurring  in  plants,  are  either  rejected  by  animals,  as  in  the 
case  of  the  characteristic  principles  of  poisonous  arid  medicinal  plants,  or  else  they 
occur  in  the  food  in  such  very  small  proportion,  that  they  cannot  possibly  contribute 
to  the  increase  of  mass  in  the  animal  body. 

"  The  chemical  analysis  of  these  three  substances  has  led  to  the  very  interesting 
result  that  they  contain  the  same  organic  elements,  united  in  the  same  proportion 
by  weight;  and,  what  is  still  more  remarkable,  that  they  are  identical  in  composi- 
tion with  the  chief  constituents  of  blood,  animal  fibrin,  and  albumen.  They  all  three 
dissolve  in  concentrated  muriatic  acid  with  the  same  deep  purple  colour;  and  even 
in  their  physical  characters,  animal  fibrin  and  albumen  are  in  no  respect  different 
from  vegetable  fibrin  and  albumen.  It  is  especially  to  be  noticed,  that  by  the  phrase, 
identity  of  composition,  we  do  not  here  imply  mere  similarity,  but  that  even  in  re- 
gard to  the  presence  and  relative  amount  of  sulphur,  phosphorus,  and  phosphate  of 
lime,  no  difference  can  be  observed." 

5012.  In  addition  to  the  information  conveyed  in  the 
preceding  quotation,  we  are  informed  in  a  note  (8)  that 


416  ORGANIC  CHEMISTRY. 

the  portion  of  wheat  flour,  above  alluded  to,  under  the 
name  of  fibrin,  is  that  which  is  not  taken  up  by  boiling  al-- 
cohol  from  the  glutinous  mass  mechanically  obtained  by 
washing  wheat  dough  in  a  bag. 

5013.  The  vegetable  fibrin  of  Liebig  is,  therefore,  the 
vegetable  albumen  of  Einhof  and  Berzelius,  or  the  zimome 
of  Taddei. 

5014.  The  statement  in  the  note,  that  "pure  gluten  is  the 
portion  of  raw  wheat  flour  which  is  soluble  in  hot  alcohol"  is 
not  consistent  with  the  allegation,  that  the  glutinous  quality 
is  due  to  a  foreign  substance  present  in  small  quantity,  and 
which  is  not  found  in  other  cerealia.     This  allegation  is, 
moreover,  inconsistent  with  the  observations  of  Einhof,  as 
stated  by  Berzelius,  that  gluten  is  found  in  rye,  barley,  and 
in  small  proportion  in  maize.     Besides,  it  is  difficult  to  be- 
lieve that  the  adhesiveness  of  wheat  dough,  to  which  it 
owes  its  power  of  confining  the  carbonic  acid  generated 
during  panification,  can  be  the  effect  of  a  small  quantity  of/ 

foreign  matter.  It  would  seem  to  require  a  quantity  of 
matter  intimately  associated  with  the  farina,  and  pervading 
the  whole  of  the  dough,  into  which  it  is  converted  in  the 
bread  making  process. 

5015.  There  seems,  however,  to  be  good  grounds  to 
suppose  the  existence  of  an  error  in  estimating  the  nourish- 
ing power  of  different  kinds  of  grain,  to  be  in  proportion 
to  the  quantity  of  glutinous  matter  obtained  from  them  by 
washing,  since  the  farina  of  maize,  which  for  equal  weight 
is  in  this  country  considered  at  least  as  nutritive  as  wheat, 
seems  to  have  not  perceptible  adhesiveness.     Hence,  the 
statement  of  Liebig,   however  inconsistent  with  precon- 
ceived opinions,  may  point  towards  an  important  truth, 
that  there  is  a  vegetable  fibrin  meriting  the  highest  rank 
as  animal  food,  which  differs  from  pure  gluten  in  not  being 
soluble  in  alcohol  nor  glutinous;  and  from  vegetable  albu- 
men, in  not  being  soluble  in  water,  nor  coagulable  by  heat. 

5016.  The  idea,  above  quoted  from  Berzelius,  respect- 
ing the  superiority  of  wheat  as  a  nutriment,  being  due  to 
its  holding  a  peculiarly  large* proportion  of  gluten,  has  ge- 
nerally prevailed ;  and  by  Sir  H.  Davy  the  opinion  was 
entertained,  that  the  wheat  of  more  southern  climates  was, 
on  account  of  a  greater  abundance  of  gluten,  more  nutri- 
tious than  grain  of  the  same  kind,  raised  in  colder  lati- 
tudes.    To  a  greater  abundance  of  the  same  matter,  has 


OF  THE  GLUTEN  AND  ALBUMEN  OF  WHEAT.      417 

been  ascribed  the  superior  capability  in  wheat  dough  of 
what  is  called  rising;  as  the  gluten,  by  preventing  the 
escape  of  carbonic  acid,  causes  the  inflation  of  innumera- 
ble little  cavities  producing  the  cellular  structure  which 
distinguishes  leavened  bread. 

5017.  It  appears,  that  during  panification  there  is  ac- 
tually a  generation  of  alcohol,  as  well  as  carbonic  acid,  so 
that  in  the  usual  process  there  is  an  incipient  fermenta- 
tion. 

5018.  Gingerbread,  however,  owes  its  lightness  to  a  dif- 
ferent process.     Being  made  of  flour  and  molasses,  with  a 
suitable  addition  of  an  alkaline  carbonate,  an  acid  is  gra- 
dually generated  by  the  absorption  of  atmospheric  oxygen, 
which  displaces    the  carbonic  acid   from  the  carbonate, 
(1198.)     The  gas,  thus  liberated  from  the  alkali,  being 
confined  by  the  gluten,  when  the  bread  is  placed  in  an 
oven,  an  inflation  of  every  part  arises  from  the  expansion 
of  the  gaseous  matter. 

5019.  A  bicarbonate  is  more  efficacious  than  pearlash 
in  causing  gingerbread  to  rise,  as  in  proportion  to  the  al- 
kali it  yields  double  the  quantity  of  gas.     A  bicarbonated 
alkali  is  found  to  act  as  a  leaven  for  cakes,  when  old  cider 
is  mingled  with  the  dough.     Tartaric  acid  has  been  used 
for  this  purpose,  and  lime  juice  might  be  employed,  or  any 
well  flavoured  vegetable  acid.     An  equivalent  portion  of 
chlorohydric  acid  might  be  resorted  to. 

5020.  It  is  supposed  that  bakers  generally  use  a  sufficiency  of  pearlash 
to  neutralize  the  acidity  which  is  liable  to  supervene  in  their  yeast  or  lea- 
ven; and  that  latterly,  carbonate  of  soda  having  become  cheaper,  has  been 
preferred.     An  erroneous  prejudice  has  existed  as  respects  this  practice, 
whereas  evidently  sourness  in  bread  must  be  more  injurious  to  health  than 
an  alkaline  acetate. 

5021.  Carbonate  of  ammonia  has  been  used,  and  is  alleged,  by  being 
vapourized  during  the  baking  process,  to  contribute  to  the  inflation  and  con- 
sequent sponginess  of  the  bread  in  which  it  is  used. 

5022.  More  than  forty  years  since,  a  candidate  for  graduation  in  our 
university,  Dr.  Pennington,  published  a  thesis,  in  which  bread  was  described 
as  being  simultaneously  salted  and  raised,  by  the  addition  to  the  dough  of 
chlorohydric  acid  and  carbonate  of  soda,  in  due  proportion.     Rolls  are  al- 
leged to  be  rendered  lighter,  when  made  with  carbonated  water,  of  the  Con- 
gress spring  at  Saratoga.     The  knowledge  which  we  now  have  of  the  equi- 
valent proportions  in  which  to  use  bases  and  acids,  renders  experiments  of 
this  kind  much  more  easy  than  they  were  at  the  period  when  Dr.  Pen- 
nington graduated.     Of  course  a  bicarbonated  alkali  should  in  all  cases  be 
preferred,  for  the  reason  above  given. 


418 


ORGANIC  CHEMISTRY. 


Legumen,  or  Vegetable  Caseine. 

5023.  The  substance  bearing  these  names,  appears  to 
be  intermediate  between  gluten  and  vegetable  albumen, 
not  being  coagulable  by  heat  like  the  one,  nor  like  the 
other  soluble  in  alcohol  while  insoluble  in  water.  It  is, 
however,  alleged  by  Liebig,  that  agreeably  to  recent  ana- 
lyses made  in  his  laboratory,  there  is  no  difference  as  re- 
spects composition,  between  gluten,  vegetable  albumen, 
vegetable  fibrin,  and  vegetable  caseine,  nor  between  these 
substances  and  those  of  the  same  names  derived  from  ani- 
mals. 

Composition  of  Vegetable  Fibrin,  Vegetable  Albumen,  Vegetable  Caseine,  and  Vegetable 

Gluten. 


VEGETABLE  FIBRIN. 


Sherer.*  a 


Carbon 

Hydrogen 

Nitrogen 

Oxygen 

Sulphur 

Phosphorus 


I. 

ii. 

in. 

53.064 

54.603 

54.617 

7.132 

7.302 

7.491 

15.359 

15.809 

15.809 

Jones.*  6 
IV. 

53.83 

7.02 

15.58 


Gluten,  as  obtained 

from  wheat  flour. 

Marcet.  c    Boussingault. 


55.7 
14.5 

7.8 


ii. 

53.5 
15.0 

7.0 


24.445 


22.285 


22.083 


a  Ann.  der  Chem.  und  Pharm.  XL.  7. 
c  L.  Gmelin's  Theor.  Chemie,  II.  1092. 


23.56  22.0  24.5 

b  Ibid.  XL.  65. 


VEGETABLE  ALBUMEN,  a 


Carbon 

Hydrogen 

Nitrogen 

Oxygen 

Sulphur 

Phosphorus 


From  Rye. 

Jones.* 

54.74 

7.77 

15.85 

>     21.64 


Carbon    - 
Hydrogen 
Nitrogen 
Oxygen,  &c. 


Wheat. 

Jones.* 

55.01 

7.23 

15.92 


21.84 


Gluten. 

Varrentrapp  &  Will.* 

54.85 

6.98 

15.88 

22.39 


ingault. 

i27 


52 

6.9 

18.4 

22.0 


Almonds. 

Jones.* 

57.03 

7.53 

13.48 


21.96 


Varrentrapp  and  Will.* 


15.70 


a  Ann.  der  Chem.  und  Pharm.  XL.  66,  and  XXXIX.  291. 


VEGETABLE  CASEINE.  a 


Scherer.* 

54-138 

7.156 

15.672 

23.034 


Jones.* 

55.05 
7.59 
15.89 
21.47 


Sulphate  of  Caseine 

and  Potash. 
Varrentrapp  and  Will. 


Carbon 
Hydrogen 
Nitrogen 
Oxygen,  &c. 

a  Ann.  der  Chem.  und  Pharm.  XXXIX.  291,  and  XL.  8  and  67. 


5141 

7.83 
14.48 


51.24 

6.77 

13.23 


OF  VEGETABLE  COLOURING  MATTER.  419 

VEGETABLE  GLUTEN. 

Jones.*  a  Boassingault. 


Carbon         -  -  55.22  54.2  52.3 

Hydrogen    -  -  7.42  7.5  6.5 

Nitrogen      -  -  15.98  13.9  18.9 

Oxygen,  &c.  -  21.38  24.4  22.3 

a  Ann.  der  Chem.  und  Pharm.  XL.  66. 

The  pure  gluten,  analyzed  by  Jones,  was  that  portion  of  the  raw  gluten  from 
wheat  flour  which  is  soluble  in  hot  alcohol.  The  insoluble  portion  is  vegetable  fibrin, 
the  analysis  of  which  has  been  already  given. 

Composition  of  Animal  Caseine.  a 

Scherer. 


From  fresh 
milk. 

From  sour  milk. 

.  A  

From  milk 
by  acetic  acid. 

Albuminous  sub- 
stance in  milk,  b 

I. 

54.825 
7.153 
15.628 

^^ 
II. 

54.721 
7.239 
15.724 

^l 

in. 
54.665 
7.465 
15.724 

IV. 

54.580 
7.352 
15.696 

54.507 
6.913 
15.670 

22.394 

22.316 

22.146 

22.372 

22.910 

Carbon 
Hydrogen 
Nitrogen 
Oxygen       > 
Sulpnur      £ 

a  Ann.  der  Chem.  und  Pharm.  XL.  40  et  seq. 

b  This  substance,  called,  in  German,  zieger,  is  contained  in  the  whey  of  milk 
after  coagulation  by  an  acid.  It  is  coagulated  by  heat,  and  very  much  resembles 
albumen. 

Mulder,  a 

Carbon 54.96 

Hydrogen 7.15 

Nitrogen 15.89 

Oxygen         .....        21.73 
Sulphur 0.36 

a  For  the  analysis  of  vegetable  caseine,  see  the  preceding  page. 

Of  Vegetable  Colouring  Matter,  or  Dyes,  and  of  Dyeing. 

5024.  None  of  the  operations  of  nature  are  more  inscrutable,  than  those 
by  which  organic  substances  are  endowed  with  the  immense  variety  of 
colours  with  which  vegetables  and  animals  are  adorned.      The  chemist 
may  know  how  to  elaborate  dyes,  to  fix  them,  and  in  fixing  them,  by  the 
interposition  of  mordants,  to  vary  their  hues;  but  excepting  the  influence  of 
transparent  media,  or  of  crystalline  structure,  in  dispersing  refracted  or  po- 
larized rays,  he  is  still  quite  ignorant  of  the  differences  in  the  arrangement 
of  particles  which 'give  rise  to  diversity  of  colour;  or  of  the  mode  in  which 
chemical  combination  causes  the  various  colours  of  precipitates. 

5025.  Colouring  substances  or  dyes  are  divided  into  substantive  and  ad- 
jective dyes.    The  former,  with  little  disposition  to  dissolve  in  water,  have  a 
strong  affinity  for  the  fibre  to  be  dyed,  and  enter  directly  into  union  there- 
with.    The  adjective  colours,  having  little  or  no  affinity  for  the  fibre  to 
which  they  are  to  be  attached,  an  union  is  produced  by  an  intermediate  sub- 
stance having  an  affinity  for  both,  and  which  is  consequently  called  a  mor- 
dant, from  mordant,  biting,  in  French.    In  some  cases  the  colour  is  changed 
by  the  mordant,  in  others  improved  and  heightened. 

5026.  Lakes  are  precipitates  of  colouring  matters,  made  by  the  sub- 
stances used  as  mordants.     By  presenting  them,  in  a  proper  state  of  com- 
bination, to  colouring  matter,  both  alumina  and  oxidized  iron  are  used  ex- 

54 


420  ORGANIC  CHEMISTRY. 

tensively  as  mordants,  and  for  the  formation  of  lakes.  By  means  of  cochi- 
neal dye  and  protoxide  of  tin,  the  well  known  scarlet  of  the  military  uni- 
form of  Great  Britain  is  produced.  The  ordinary  carmine  of  commerce, 
is  a  lake  produced  from  that  dye  by  alumina.  Chinese  carmine  is  pro- 
duced by  the  same  dye  with  protoxide  of  tin. 

5027.  Indigo  is  a  substantive  dye  which  is  made  to  attach  itself  to  woollen 
cloth,  without  the  aid  of  a  mordant.     By  digestion  with  lime  and  green  sul- 
phate of  iron,  it  is  rendered  white.     When  in  this  state  it  unites  with  the 
woollen  fibre,  and  by  subsquent  exposure  to  air,  regains  its  blue  colour. 
The  rationale  of  this  process,  suggested  by  Liebig,  is  as  follows : — 

5028.  A  soluble  colourless  substance,  which  may  be  called  indigogene 
being  generated  in  the  indigo  plant,  is  by  oxidizement  converted  into  the 
insoluble  blue  indigo  of  commerce.     In  the  process  of  dyeing,  the  oxide  of 
indigogene  or  blue  indigo  is  deoxidized  by  protoxide  of  iron,  liberated  by 
the  lime  from  the  sulphate,  and  is  thus  restored  to  its  whiteness  and  so- 
lubility.    In  this  state,  combining  with  the  organic  fibre,  it  is  subsequently 
reconverted  into  insoluble  blue  indigo  by  union  with  atmospheric  oxygen. 

5029.  But  Kane  conceives,  that  Dumas  has  proved  by  analysis,  that  so- 
luble white  indigo  is  a  hydruret  of  insoluble  blue  indigo.     Each  atom  of 
the  hydruret  being  deprived  of  an  atom  of  hydrogen,  during  the  macerating 
process  of  the  manufacturer,  the  indigo  loses  its  solubility  and  assumes  its 
appropriate  blue  colour.     In  this  state  it  is  found  in  commerce,  and  when 
subjected  to  the  process  of  the  dyer,  above  alluded  to,  is  made  to  receive  an 
atom  of  hydrogen  liberated  by  an  atom  of  water,  of  which  the  oxygen  is 
simultaneously  seized  by  the  protoxide  of  iron.     The  hydruret  thus  formed 
combining  with  the  organic  fibre,  while  colourless  and  soluble,  by  subse- 
quent exposure  to  air  is  dehydrogenated,  and  thus  again  converted  into  an 
insoluble  blue  dye. 

5030.  Indigo  is  soluble  in  concentrated  sulphuric  acid,  especially  the 
fuming  acid  of  Nordausen.     The  solution  thus  made,  yields  what  is  called 
the  Saxon  blue.     Previously  to  the  immersion  of  the  cloth,  the  solution  is 
neutralized  by  carbonate  of  soda,  which  uniting  with  the  acid,  the  dye  at- 
taches itself  to  the  organic  fibre,  whether  it  be  wool,  silk,  or  cotton. 

5031.  Indigo  forms  various  peculiar  combinations,  to  which  it  would  be 
inexpedient  to  direct  the  attention  of  those  who  study  chemistry  only  as 
auxiliary  to  medicine.    , 

Of  the  Colouring  Matter  of  Leaves  and  Floivers. 

5032.  The  green  colour  of  plants  is  said  to  be  due  to  the  pressure  of  a 
substance  called  chlorophyll.     This  has  not  been  obtained  sufficiently  pure 
to  have  any  formula  assigned  to  it.     It  does  not  contain  nitrogen,  is  inso- 
luble in  water,  but  soluble  both  in  ether  and  alcohol,  and  in  strong  acids. 
From  these,  however,  it  precipitates  on  dilution.     It  combines  with  bases. 

5033.  Berzelius  conceives  three  kinds  of  chlorophyll  to  exist.    The  first, 
existing  in  fresh  leaves,  dissolves  in  acetic  acid  with  a  rich  grass-green  co- 
lour; the  second,  formed  from  the  first  by  drying,  gives  with  the  same  acid 
an  indigo  blue  solution;  the  third,  which  exists  principally  in  the  dark 
leaved  plants,  is  brownish  green. 

5034.  So  potent  is  the  colouring  power  of  chlorophyll,  that  Berzelius 
has  calculated  that  all  the  foliage  of  a  large  tree  seldom  contains  ten  grains 
of  it.     When  trees  change  colour  in  the  fall,  chlorophyll  is,  according  to. 
the  same  chemist,  replaced  by  other  colouring  matter. 


OP  OILS.  421 

5035.  Chlorophyll  floats  in  the  cells,  existing  in  the  green   leaves  of 
plants  in  general,  in  the  form  of  green  globules,  from  which  it  may  be  ex- 
tracted by  ether.     The  etherial  solution  thus  obtained,  being  subjected  to 
the  distillatory  process  to  remove  the  solvent,  the  residue  is  digested  in  al- 
cohol, which  takes  up  impure  chlorophyll.     The  alcohol,  being  entirely  re- 
moved, the  residual  matter  is  subjected  to  concentrated  chlorohydric  acid, 
by  which  a  fine  emerald  green  colouring  matter  is  dissolved.     This  precipi- 
tating on  dilution,  is  digested  in  a  strong  lixivium  of  potash.     The  resulting 
compound  being  dissolved  by  water,  the  solution,  after  being  filtered,  is  satu- 
rated with  acetic  acid,  when  beautiful  green  flocks  precipitate  of  pure  chlo- 
rophyll, which  in  drying  become  bluish  green.     Graham,  907. 

Of  Oils. 

5036.  When  not  figuratively  used  to  describe  substances 
having  only  an  oleaginous  consistency,  like  oil  of  vitriol, 
the  word  oil  has  been  applied  to  two  classes  of  substances, 
differing  in  most  respects  in  their  properties  and  chemical 
constitution.     One  of  these  classes  has  been  called  fixed, 
from  their  insusceptibility  of  being  distilled  without  decom- 
position.    But  as  margaric  acid,  a  principal  constituent  in 
a  majority  of  fixed  oils,  and  spermaceti,  a  concrete  animal 
oil,  may  be  distilled  without  change,  this  definition  is  not 
universally  consistent.     It  would,  therefore,  be  preferable 
to  designate  as  fixed  oils  those  which  do  not  spontaneous- 
ly evaporate  when  exposed  to  the  air,  or  which  are  not 
vaporized  at  the  boiling  point  of  water,  when  subjected  to 
the  distillatory  process  with  that  liquid.* 

Of  Fixed  Oils. 

5037.  I  propose  rather  to  treat  briefly  of  the  general 
properties  of  fixed  oils,  of  their  composition,  and  of  the 
theory  of  their  conversion  into  soap,  than  to  give  an  ac- 
count of  each  of  them  particularly. 

5038.  There  is  no  essential  difference  between  fat,  and 
oil.     The  one  differs  from  the  other,  merely,  in  a  greater 

*  By  distinguished  writers,  such  oils  have  been  designated  as  fat  or  unctuous  oils. 
But  as  unctuous  and  oily  are  synonymous  words,  and  as  fats  are  concrete  oils,  the  use 
of  the  words  in  question,  in  the  way  alluded  to,  were  equivalent  to  saying  oily  oils, 
or  fat  fats.  The  word  greasy  though  inelegant,  would  be  more  appropriate,  simi- 
larly applied,  than  unctuous,  as  one  of  the  most  characteristic  differences  between 
volatile  and  fixed  oils  is  the  presence  of  this  property  in  the  one,  and  its  absence 
from  the  other. 

Kane  distinguishes  fixed  oils  as  saponifiable.  But  as  chemists  consider  compounds 
of  certain  oily  acids  with  bases  as  soaps,  evidently  (4032)  fixed  oils  are  native 
compounds  meriting  this  appellation;  as  will  shortly  be  made  more  evident.  It  is 
the  oily  acid  ingredient,  not  the  compound  formed  with  it,  which  can  be  saponified. 
I  should  conceive  it,  therefore,  more  proper  to  designate  the  oils  in  question,  as 
soap  oils,  or  unctuous  soaps. 


422  ORGANIC  CHEMISTRY. 

propensity  to  the  fluid  state.  That  which  may  pass  for 
fat  in  winter,  may  become  oil  in  summer.  The  oils  of  an- 
imals are  generally  in  the  solid  state  of  fat;  those  of  ve- 
getables are  generally  liquid. 

5039.  Although  fats  and  oils,  as  they  exist  in  nature, 
appear  to  be  homogeneous,  they  all  consist  of  two  or  more 
oleaginous  substances,  of  which  one  is  more  fluid  than  the 
rest.     The  more  fluid  ingredient,  named  olein,  is  found  in 
its  chemical  habitudes  and  composition  to  be  the  same  in 
a  great  majority  of  instances,  but  the  less  fluid  portion  con- 
sists very  extensively  of  a  matter  called  stearine,  more  or 
less  associated  with  another,  rather  more  fusible  and  much 
more  soluble  in  alcohol  and  ether,  called  margarine.     In- 
deed, this  last  mentioned  substance  abounds  in  human  fat, 
and  in  that  of  some  other  animals,  and  in  vegetable  oils 
predominates.     Besides  margarine  and  stearine,  the  fol- 
lowing analogous  substances  have  been  noticed  in  various 
kinds  of  fat,  or  oily  matter;  as  for  instance,  spermaceti  in 
the  cachalot  whales;  delphinine  in  the  oil  of  the  dolphin 
and  common  whale;  butyrin,  caproin  and  caprin  in  butter; 
myristicine  in  butter  of  nutmegs;  ricino  stearine,  ricino 
olein,  and  ricin,  in  ricinus  communis;  crotonine  in  the  oil 
of  crotontiglium;  cocostearine  in  cocoa  nut  oil ;  palmatine 
in  palm  oil.* 

5040.  Spermaceti  is  obtained,  as  is  well  known,  from 
the  crania  of  cachalot  whales,  whence  its  inappropriate 
name,  from  sperma,  seed,  and  cetus,  a  whale.     The  part 
allotted  to  it,  is  analogous  to  that  which  stearine  performs 
in  tallow  or  suet ;  but  that  it  differs  in  composition  has 
been  already  mentioned,  and  to  keep  it  in  fusion  requires 
a  temperature  peculiarly  high.     Hence  it  crystallizes  from 
its  solvent  olein,  at  the  ordinary  temperature  of  the  air. 

5041.  The  summer  strained  and  winter  strained  oils  of 
commerce,  severally  consist,  the  one  of  a  large  portion  of 
olein,  with  a  small  proportion  of  stearine,  the  other  of  the 
same  materials,  but  with  a  greater  proportion  of  the  more 
solid  constituent.     The  appellation  given  to   these  oils, 
conveys  the  idea  of  the  fact,  that  the  one  is  obtained  by 

*  Mr.  Stenhouse  having  isolated  the  stearine  of  palm  oil,  alleges  its  formula  to  be 
as  follows,  C33  H66  O4;  and  that  it  consists  of  one  atom  of  a  peculiar  fat  acid,  which 
he  calls  the  palmatic,  C32  H62  -j-  O3,  and  one  atom  of  oxide  of  glyceryl.  He  assigns, 
however,  a  new  formula  for  the  latter,  C3  H*  Qi,  which  Berzelius  does  not  consider 
as  admissible  upon  the  evidence  of  this  author  alone,  while  inconsistent  with  the 
previous  analysis  made  by  Liebig  and  Pelouze. 


OF  OILS.  423 

straining  at  a  lower  temperature  than  the  other.  In  like 
manner,  a  liquid  may  be  obtained  from  crude  olive  oil 
when  thickened  by  cold,  which,  when  employed  to  lubri- 
cate delicate  machinery,  like  that  of  watches,  does  not,  by 
congealing,  impede  the  movements  in  frosty  weather. 

5042.  Subsequently,  the  following  more  effectual  process 
was  discovered  by  Chevreul,  of  isolating  the  constituents 
of  oil,  whether  liquid  or  in  the  concrete  state  of  fat. 

5043.  The  whole  being  dissolved  in  boiling  alcohol,  the 
margarine  and  stearine  separate  by  congelation  on  cool- 
ing.    The  mass  thus  separated  is  subjected  to  ether,  with 
as  much  heat  as  the  low  boiling  point  of  this  solvent  will 
permit.    The  margarine  is  taken  up  by  the  ether,  in  which 
it  is  soluble,  leaving  the  stearine  undissolved.     Of  course, 
by  distillation,  the  alcohol  may  be  removed  from  the  olein, 
the  ether  from  the  margarine. 

5044.  Stearine  is  white,  crystallizable,  soluble  in  alcohol 
when  boiling,  but  insoluble  in  cold  alcohol,  water,  or  ether. 

5045.  It  is  best  obtained  from  mutton  suet,  by  washing 
with  ether  as  long  as  any  thing  is  taken  up,  or  by  agitating 
melted  suet  with  six  times  its  volume  of  ether,  and  subject- 
ing the  mass,  when  cold,  to  intense  pressure.     In  either 
case  the  ether  removes  the  olein  and  margarine,  leaving 
the  stearine  pure.     Thus  obtained,  it  is  usually  crystalline. 
Like  spermaceti  it  is  not  in  the  least  greasy  to  the  touch, 
and  is  easily  pulverized.     It  is  insoluble  in  ether  or  alco- 
hol, when  cold,  but  is  soluble  in  those  liquids  when  boiling, 
and  by  refrigeration  crystallizes  from  the  solution. 

5046.  Stearine  consists  of  an  atom  of  glycerine  or  oxide 
ofglyceryl,  C  6  H  7  O5 
Two  atoms  stearic  acid,                                    C136  H132  O10 
Two  atoms  of  water,      -             -            -  H  2  O 2 


Hence  the  formula  of  stearine  is  -        C142  H141  O17 


5047.  Margarine  is  obtained  from  the  ether  employed 
as  above  mentioned  to  depurate  stearine,  by  vaporizing 
the  ether,  and  redissolving  the  mass  in  boiling  alcohol. 
From  this  alcoholic  solution  the  margarine  crystallizes,  on 
cooling,  any  olein  which  may  be  present  remaining  dis- 
solved. Excepting  its  greater  fusibility,  melting  at  118°, 
and  its  solubility  in  alcohol  and  ether,  already  mentioned, 
it  much  resembles  stearine. 


424  ORGANIC  CHEMISTRY. 

5048.  Its  composition  will  appear  from  the  following 
formula  of  its  ingredients : — 


One  atom  oxide  of  glyceryl,  -         C  6  H  7  O 5 

Two  „  margaric  acid,  C68  H66  O 6 

One  „  water,  -  -  HO 


Formula  of  margarine,     -  C74  H74  O12 

5049.  Olein. — In  concrete  oils,  usually  called  fats,  olein 
exists  in  but  a  small  proportion,  but  constitutes  a  large 
portion  of  all  the  fixed  oils  which  are  not  drying,  or,  in 
other  words,  capable  of  hardening  by  exposure  to  the  air. 
As  found  in  nature,  it  always  holds  more  or  less  stearine 
and  margarine.     Margarine  abounds  in  olive  oil.     In  the 
oil  obtained  from  sweet  almonds  by  expression,  there  is 
less  margarine  in  proportion  to  the  olein  than  in  any  other. 
In  this  respect  rape  seed  oil  approximates  most  nearly  to 
the  oil  of  sweet  almonds. 

5050.  Olein  is  best  obtained  by  dissolving  almond  oil  in 
ether  heated  nearly  to  its  boiling  point,  and  afterwards 
cooled  till  the  margarine  congeals,  so  as  to  be  separated 
by   straining.     Olein,   thus   obtained,   remains   liquid   at 
zero,  F. 

5051.  The  composition  of  olein  is  inferred  to  be  as  fol- 
lows : — 

One  atom  of  glyceryl,       -  -  C 6  H 7  O 5 

Two       „       oleic  acid,  C88  H78  O 8 

Two      „       water,          -  -  -  H2  O2 


Hence  the  formula  of  olein  is        -  -        C94  H87  O15 


Of  Saponification. 

5052.  In  treating  of  glyceryl  and  cetyl  (4029,  4036),  it 
has  been  explained,  that  all  fixed  oils,  whether  concrete  or 
liquid,  are  supposed  to  be  compounded  of  two  ingredients, 
one  acting  as  a  base,  the  other  as  an  acid,  and  that  in  a 
great  majority  of  cases  an  oxide  of  glyceryl  is  inferred  to 
be  the  base.  Hence,  when  substances  in  which  it  exists  in 
this  capacity  are  boiled  with  an  alkaline  oxide,  the  oxide  of 
glyceryl  is  dispossessed  of  its  acid.  The  acids  thus  trans- 


OF  SAPONIFICATION.  425 

ferred  to  the  alkaline  oxide  have  been  named  from  the 
substances  by  which  they  are  respectively  yielded. 

Thus  Stearine  gives  Stearic  acid. 

Margarine  Margaric  acid. 

Olein  Oleic  acid. 

Butyrin      )  Butyric  acid. 

Caproin  Caproic  acid. 

Caprin        }  Capric  acid. 

Delphinine  Delphinic  acid. 

Myristicine  of  Nutmeg  Butter     Myristicic  acid. 

Ricino  Stearine  }  Ricino  Stearic  acid. 

Ricino  Olein  >    Castor  Oil    Ricino  Oleic  acid. 

Ricin  )  Ricinic  acid. 

Crotonine,  Oil  of  Croton  Tiglium  Crotonic  acid. 
Cocoa  Stearine  Cocoa  Stearic  acid. 

5053.  It  remains  doubtful  whether  the  acids  thus  elabo- 
rated exist  ready  formed,  in  union  with  the  oxide  of  glyce- 
ryl, or  whether  both  base  and  acid  are  generated  during 
the  process  of  saponification.     The  former  opinion,  how- 
ever, is  supported  by  the  fact,  that,  by  the  direct  union  of 
stearic  acid  with  the  oxide  of  ethyl,  an  oil   is  formed, 
which,  on  being  cooled  below  90°,  solidifies  with  all  the 
a~ppearance  of  a  fat.    If  the  artificial  fat,  consisting  thus  of 
ethyl,  be  boiled  with  caustic  potash,  the  results  of  the  reac- 
tion of  that  alkali  with  stearine,  under  similar  circum- 
stances, are  exactly  reproduced ;  except  that  while  stea- 
rate  of  potash  is  formed  in  both  cases,  an  oxide  of  ethyl  is 
liberated  in  the  latter  instead  of  the  oxide  of  glyceryl.     It 
may,  therefore,  be  presumed,  that  stearine,  olein,  &c.,  may 
be  regarded  as  definite  salts  formed  by  the  union  of  the  fat 
acids,  which  are  respectively  produced  from  them  with  the 
oxide  of  glyceryl. 

5054.  The  oxide  of  glyceryl  is  the  base  of  a  majority  of 
oleaginous  bodies,  the  difference  between  them  being  pro- 
duced by  the  diversity  of  the  acids  which  enter  into  their 
composition.    In  the  single  case  of  spermaceti  this  general 
rule  is  reversed,  the  acids  being  the  same  as  those  which  are 
present  in  large  quantities  in  the  fat  of  men  or  of  sheep, 
while  the  base  is  the  oxide  of  another  radical,  cetyl,  capa- 
ble, as  already  mentioned,  of  combining  with  sulphuric  acid 
to  form  a  compound  corresponding  to  sulphovinic  acid,  and 
likewise  of  existing  as  a  hydrate,  or  in  a  state  analogous  to 


426  ORGANIC  CHEMISTRY. 

that  of  ethyl  in  alcohol.  It  would  appear,  therefore,  that 
while  we  must  regard  common  tallow,  or  suet,  as  a  stea- 
rate,  margarate,  and  oleate  of  oxide  of  glyceryl,  sperma- 
ceti must  be  looked  upon  as  a  margarate  and  oleate  of 
oxide  of  cetyl.  It  may  be  observed,  that  the  view  of  the 
composition  of  the  different  fats  here  given,  and  founded 
on  the  fact  of  their  decomposition  by  alkalies  into  an  acid 
and  a  base,  is  confirmed  by  the  result  of  direct  analysis, 
which,  when  disposed  in  a  rational  formula,  in  all  cases 
gives  the  number  of  atoms  necessary  to  represent  the  or- 
ganic acid  and  base  which  they  are  supposed  to  contain. 

5055.  In  a  paper  published  in  the  last  number  of  the 
American  Journal  of  Science,  Dr.  Smith,  as  the  result  of  a 
careful  analytical  investigation,  alleges  that  ethalic  acid  is 
the  sole  electro-negative  product  of  reaction  of  spermaceti 
with  alkalies,  in  the  process  of  saponification ;  and  that 
the  margaric  and  oleic  acids,  are  not  evolved  by  that  pro- 
cess.   He  supposes  that  an  atom  of  spermaceti,  C64  H64  O4, 
is  separated  by  the  action  of  potash  into  an  atom  of  ethalic 
acid,  C32  H31  O3,  and  one  atom  of  ethal,  C32  H33  O.     From 
the  fact  that  the  ethal,  thus  separated,  by  a  farther  treat- 
ment with  potash  at  a  high  temperature  and  with  access 
of  air,  may  be  completely  converted  into  ethalic  acid,  Smith 
infers  that  the  saponification  of  spermaceti  differs  from 
that  of  ordinary  fats,  since  the  glycerine,  which  they  yield, 
is  insusceptible  of  further  acidification:  also  that  sperma- 
ceti must  be  regarded  as  a  homogeneous  fatty  body,  not 
containing,  ready  formed,  either  the  acid  or  base  which  it 
affords  when  treated  with  alkalies. 

Properties  of  the  Fixed  Oils. 

5056.  I  infer  that  fixed  oils,  when  not  accompanied  by 
any  other  matter,  are  nearly  colourless,  insipid,  and  in- 
odorous.    The  smell  and  taste  produced  by  them,  in  the 
state  in  which  they  come  under  our  observation,  is  ob- 
viously due  to  some  volatile  oil  or  acid  with  which  they  are 
associated.     Their  colour  is  evidently  caused  by  foreign 
matter,   as   they   may   be   decolorized   by   charcoal.     In 
some  instances  impurities  exist  in  them  naturally,  in  others 
are  produced  during  their  elaboration  or  subsequent  expo- 
sure to  atmospheric  oxygen,  by  which  they  are  more  or 
less  oxidized,  and  brought  into  the  state  called  rancidity. 
The  fine  flavour  of  fresh  grass  butter,  and  the  nauseous 


PROPERTIES  OF  THE  FIXED  OILS.  427 

savour  of  that  which  is  rancid,  are  neither  of  them  to  be 
ascribed  to  the  pure  oil  of  butter,  which,  when  fresh  made 
from  cream  obtained  from  cows  fed  on  hay,  although 
sweet,  is  not  highly  flavoured. 

5057.  The  difference  between  cold  pressed  olive,  or  cas- 
tor oil,  and  that  obtained  with  the  aid  of  heat,  shows,  that 
in  proportion  as  substances  of  this  kind  are  more  near  to 
the  natural  state,  the  less  they  are  endowed  with  colour,  or 
any  activity  as  respects  taste  or  smell. 

5058.  Boiling  with  magnesia,  diminishes  the  unpleasant 
smell  and  taste  of  rancid  oils,  by  removing  the  acid  which 
causes  those  defects. 

5059.  As  in  every  animal,  and  in  a  great  number  of  ve- 
getables, fixed  oils  are  more  or  less  to  be  found,  of  which 
each  affects  the  sight,  the  smell,  and  taste,  in  a  different 
way,  it  might  be  imagined  that  there  was  much  difference 
in  the  proportions  of  the  ultimate  elements  of  which  they 
are  formed.* 

5060.  But  it  has  already  been  made  evident,  that,  in  or- 
ganic products  especially,  diversity  of  properties,  is  not  at- 
tended by  corresponding  diversities  in  the  proportions  of 
ultimate  elements.    However,  in  the  case  of  the  substances 
under  consideration,  it  is  probable  that  there  would  be  very 
little  difference  in  properties  to  be  accounted  for,  could 
those  substances  be  obtained  free  from  certain  volatile  oils 
and  acids  by  which  they  are  accompanied.     It  is  not, 
therefore,  surprising,  that  the  results  of  ultimate  analysis 
do  not  display  any  material  difference  as  to  the  ratio  in 
which  carbon,  hydrogen,  and  oxygen,  enter  into  their  com- 
position. 

5061.  Agreeably  to  quotations  made  by  Raspail,  of  the 
ultimate  analysis,  by  various  distinguished  chemists,  of 
twelve  species  of  oils,  including  white  wax,  it  appears  that 
the  differences  resulting  from  the  diversity  in  composition, 

*  Mr.  M.  S.  Wright  has,  by  means  of  ether,  extracted  from  spurred  rye  or  ergot 
(secule  coruntum)  a  fat  and  saponifiable  oil,  which  has  the  odour  of  the  ergot,  and 
which  he  alleges  to  have  a  like  efficacy.  This  oil  is  changed  by  exposure  to  air,  es- 
pecially if  simultaneously  heated,  becoming,  in  consequence,  brown.  Nevertheless 
it  may  be  kept  unchanged,  in  well  closed  vessels.  It  is  soluble  in  alcohol,  ether, 
sulpho-carbonic  acid,  and  fixed  and  volatile  oils.  Berzelius  deems  it  worthy  of  a 
more  thorough  examination.  Report  for  1841,  page  150. 

It  may  be  inferred,  so  far  as  reliance  is  to  be  placed  on  the  statement  of  Mr. 
Wright,  that  the  active  principle  of  ergot  is  associated  with  the  oil  abovementioned. 
No  reference  is  made  to  the  ergotin  of  Wiggers,  supposed  by  him  to  be  the  active 
principle  of  ergot.     U.  S.  Dispensatory,  585. 
55 


428  ORGANIC  CHEMISTRY. 

are  less  than  those  arising  from  variation  in  the  manipula- 
tions of  the  different  analysts. 

5062.  There  seems,  however,  to  be  some  justification 
for  the  idea,  that  in  concrete  oils  there  is  more  carbon; 
and  that  solubility  in  alcohol  increases  with  the  proportion 
of  oxygen. 

5063.  The  carbon  in  the  less  fluid  portion  of  olive  oil  is 
to  that  in  the  more  fluid  portion,  as  82-?<k  to  76Tw,  while 
the  oxygen  of  the  latter,  which  is  the  only  part  soluble  in 
alcohol,  is  to  the  former,  as  12-dnr  to  6. 

5064.  This  inference  is  supported  by  the  fact,  that  while 
the  fusing  points  of  spermaceti  and  beeswax  are  pre-emi- 
nently high,  so  likewise  is  their  proportion  of  carbon. 

5065.  Fixed  oils  are  all  more  or  less  liable  to  a  slow 
union  with  atmospheric  oxygen,  by  which  they  are  thick- 
ened and  rendered  less  fit  for  combustion  in  lamps:  but 
some  oils  are  susceptible,  in  this  wray,  of  attaining  a  de- 
gree of  induration,  forming  on  the  surface  an  adhesive  and 
elastic  pellicle  resembling  gum  elastic.     This  tendency  is 
increased  by  boiling  the  oil  from  three  to  six  hours  with 
from  a  half  ounce  to  an  ounce  of  litharge,  and  one-fourth 
of  an  ounce  of  sulphate  of  zinc,  by  which  mucus  is  alleged 
to  be  coagulated,  which  protects  the  oil  from  oxidation  by 
atmospheric  oxygen. 

5066.  The  oils  capable  of  being  thus  changed  are  called 
drying  or  siccative  oils.     Berzelius  applies  the  term  "  non 
siccative"  to  those  which  are  not  capable  of  indurating  by 
exposure.     Linseed  oil  is  the  most  abundant  of  the  drying 
oils,  and  hence  is  most  employed  in  making  pigments  and 
varnishes.     The  oils  of  hemp  seed,  of  nuts,  of  the  seeds  of 
the  ricinus  communis,  of  croton  tiglium,  of  the  belladonna, 
of  tobacco,  of  the  sunflower,  are  placed  under  the  sicca- 
tive head  by  the  same  author. 

5067.  The  drying  oils  are  said  to  consist  of  the  oxide 
of  glyceryl  united  to  a  peculiar  liquid  acid  differing  from 
oleic  acid.* 

*  Liebig  alleges  himself  to  have  ascertained  that  the  presence  of  glyceryl  in  oil,  is 
indispensable  to  qualify  it  for  a  varnish  ;  since  neither  the  olein  alone,  nor  its  combi- 
nation with  margaric  acid,  produces,  with  oxidized  lead,  a  varnish  capable  of  speedily 
drying. 

The  success  of  the  following  process,  recommended  by  Mr.  Jonas,  seems  to  show 
that  the  oxide  of  lead  may  be  replaced  in  the  usual  process  by  another  oxidizing 
agent.  To  100  pounds  of  oil,  heated  previously  in  a  copper  boiler,  add,  drop  by  drop, 
from  two  to  four  "  gros"  of  concentrated  nitric  acid,  agitating  the  oil  continually. 
The  acid  is  decomposed  with  a  lively  effervescence.  The  oil,  after  this  treatment, 


OF  VOLATILE  OILS.  429 

5068.  When  oils  are  made  to  present  an  extensive  sur- 
face to  the  air  by  being  distributed  throughout  the  fibres 
of  cotton,  as  when  damaged  candles  are  heated  and  pressed 
to  separate  the  tallow  from  the  wicks,  spontaneous  inflam- 
mation is  liable  to  ensue.     If  paper,  linen,  tow,  wool,  cot- 
ton, straw,  wood,   shavings,   moss,  or  soot,   be   imbued 
slightly  with  linseed  or  hemp  seed  oil,  and  exposed  to  the 
sun  and  air,  especially  when  wrapped  up,  or  piled  so  as  to 
form  a  heap,  spontaneous  heat,  smoke,  or  ultimately  com- 
bustion, is  apt  to  follow.    If  linseed  oil  and  pulverized  per- 
oxide of  manganese  be  triturated  together,  a  soft  lump, 
formed  of  the  mixture,  will  soon  become  ignited.* 

OF  VOLATILE  OILS. 

Of  the  Resemblances  and  Dissimilarities  of  the  Fixed  and 

Volatile  Oils. 

5069.  Volatile  oils  resemble  fixed  oils  as  respects  com- 
bustibility, solubility  in  ether,  and  insolubility  in  water. 
They  may,  however,  be  considered  as  much  more  liable  to 
inflammation  than  fixed  oils,  and  as  not  being  so  utterly 
insoluble  in  water. 

5070.  As  fixed  oils  do  not  vaporize  without  being  sub- 
jected to  a  heat  adequate  to  effect  their  partial  decompo- 
sition into  vapour  or  gas,  they  take  fire  only  when  in  con- 
tact with  an  ignited  body  sufficiently  large  in  proportion 
to  raise  them  to  a  red  heat.    Hence  a  comparatively  small 
quantity  of  a  fixed  oil,  poured  upon  embers,  causes  a  co- 
pious inflammation;  but  if  the  quantity  be  sufficiently  in- 
creased, the  embers  may  be  extinguished  by  being  cooled 
below  ignition,  and  shielded  from  contact  with  the  air. 

being  allowed  to  cool,  and  to  remain  at  rest,  by  depositing  a  yellow  mucus  it  be- 
comes,  after  a  few  days,  clear,  and  may  be  decanted  from  the  sediment,  forming  an 
excellent  varnish.  Report  on  Chemistry,  by  Berzelius,  for  1841,  page  143. 

*  By  the  reaction  with  nitric  acid,  or  still  better  with  the  red  fumes  of  nitrous 
acid,  olein  is  resolved  partly  into  another  fat  oil,  called  elaidine,  consisting  of  a  fat 
acid,  distinguished  as  the  elaidic,  and  glycerine.  At  the  same  time  an  orange  red  oil 
is  separated. 

Elaidine,  by  the  usual  process  of  saponification,  gives  up  the  glycerine  with  which 
it  is  united,  to  the  alkali  employed.  The  resulting  elaidate  may  be  decomposed  by 
a  stronger  base,  and  elaidic  acid  liberated,  of  which  the  formula,  when  crystallised, 
is  C72  H66  O>  -f-  2HO,  being  a  bibasic  acid.  The  orange-coloured  oil,  formed  simul- 
taneously with  elaidic  acid,  has  not  been  well  examined. 

Pure  elaidic  acid  fuses  at  113°,  and  is  soluble  both  in  alcohol  and  ether. 

In  the  reaction  of  olive  oil  with  nitrate  of  mercury,  by  which  citrine  ointment  is 
made,  both  elaidic  acid  and  the  orange-red  oil  are  produced.  To  the  latter  the  cha 
racteristic  smell  and  hue  of  the  ointment  is  attributed. 


430  ORGANIC  CHEMISTRY. 

5071.  Agreeably   to   the   same   rationale,   inverting   a 
lighted  candle  causes  an  extinction  of  the  flame.     On  the 
other  hand,  any  volatile  oil  in  the  vicinity  of  an  ignited 
body  forms,  on  contact  with  the  air,  a  superstratum  of  va- 
pour intermingled  with  atmospheric  oxygen,  so  as  to  con- 
stitute an  inflammable  mixture.     Hence  the  approach  of 
any  thing  ignited  or  inflamed,  causes  a  conflagration  of  the 
whole  surface.     This  makes  it  evident  wherefore,  in  the 
combustion  of  fixed  oils,  as  in  lamps  and  candles,  a  wick 
is  requisite,  which  being  brought  into  a  state  of  combustion 
at  the  upper  extremity,  and  drawing  up  the  oleaginous 
matter  by  capillary  attraction,  causes  minute  portions  to 
be  successively  subjected  to  the  heat  requisite  to  a  decom- 
position into  the  combustible  gas  and  vapour,  by  which 
flame  is,  in  such  cases,  supported. 

5072.  Although  volatile  oils  may  be  described  as  im- 
miscible with  water,  they  are  not  like  those  of  the  other 
class  perfectly  insoluble  in  that  liquid.     Hence  rose  water, 
cinnamon  water,  peppermint  water,  as  well  as  many  ana- 
logous preparations,  are  formed  by  the  union  of  a  minute 
portion  of  an  essential' oil  with  water,  during  its  distillation 
from  the  native  product  containing  the  oil,  or  from  a  por- 
tion of  it  previously  procured. 

5073.  Water  by  agitation  with  a  fixed  oil,  may  acquire 
a  savour  resembling  that  associated  with  the  oil,  but  this 
is  owing  to  a  solution  of  the  foreign  matter  to  which  that 
savour  is  due,  rather  than  the  presence  of  the  oil  itself. 
Yet  the  repulsion   which   exists   between    the   oily,  and 
aqueous  particles,  causes  a  surprisingly  rapid  distribution 
of  oleaginous  liquids  over  the  surface  of  the  water,  so 
that  it  is  difficult  to  remove  every  trace  of  greasiness  after 
it  has  been  imparted.     It  is  in  consequence  of  this  proper- 
ty that  oil  has  been  found  to  abate  the  size  and  duration 
of  waves  by  lessening  that  hold  of  them,  taken  by  the 
wind;  to  which  they  owe  their  existence. 

5074.  The  great  affinity  existing  between  fixed  and  vo- 
latile oils,  renders  it  possible  to  combine  them  in  any  pro- 
portion.    The  volatile  oil,  being  usually  the  most  liquid,  is 
considered  as  the  solvent,  and  this  appears  especially  pro- 
per, when  oil,  in  the  solid  form  of  fat,  is  taken  up  by  them. 
Hence  the  efficacy  of  oil  of  turpentine  in  removing  paint, 
which  consists  of  a  drying  oil  and  the  metallic  compound, 
forming  the  pigment.     Hence,  also,  the  oil  of  turpentine 


OF  VOLATILE  OILS.  431 

is  used  to  attenuate  paints  and  varnishes,  made  with  sic- 
cative oils. 

5075.  The  readiness  with  which  fixed  oils  imbibe  those 
of  the  volatile  kind,  has  led  to  their  employment  in  se- 
curing the  delicate  essences  of  certain  flowers.     The  odo- 
riferous petals  being  stratified  between  alternate  layers  of 
carded  cotton,  imbued  with  an  inodorous  fixed  oil,  their 
essence  is  taken  up  by  the  latter,  and  is  subsequently  se- 
parated by  distillation  with  water.* 

Of  Volatile  Oils  in  particular. 

5076.  After  the  efforts  made  in  the  preceding  pages,  to 
discriminate  fixed  from  volatile  oils,  it  must  be  evident, 
that  the  latter  are  distinguished  from  the  former,  by  sus- 
ceptibility of  spontaneous  evaporation,  and  of  being  dis- 
tilled with  the  steam  of  boiling  water,  by  greater  inflamma- 
bility,   the  absence  of  greasiness,   superior   solubility  in 
water  or  alcohol,  and  lastly,  an  insusceptibility  of  being 
decomposed  by  alkaline  and  other  bases,  so  as  to  yield  to 
the  latter  saponifiable,  oily  acids.     Like  fixed  oils,  many 
volatile  oils  consist  of  a  more  fluid,  and  a  less  fluid  oil,  of 
which  the  former  is,  of  course,  more  readily  congealed  by 
cold.     They  are  also  prone,  like  fixed  oils,  to  absorb  oxy- 
gen, and  to  have  a  portion  of  their  hydrogen  removed  by 
uniting  therewith;  being  thus  partially  converted  into  a 
resinous  mass,  which  remains  in  solution  in  the  rest  of  the 
oil. 

5077.  By  some  chemists,  the  less  fusible  or  liquid  por- 
tion is  called  stearopten,  the  more  liquid  part,  elaopten. 
By  others,  the  words  stearessence  and  oleessence  are  sub- 
stituted, respectively,  for  the  names  above  mentioned. 

5078.  In  some  respects  there  is  a  great  analogy  in  the 
properties  of  volatile  oils  and  ethers.    The  latter  as  respects 
volatility,  incapacity  to  mix  with  water,  solubility  in  alco- 

*  For  removing  oils  from  clothes,  oil  of  turpentine  or  any  other  volatile  oil  may 
be  used,  burfollowed  by  some  inconvenience  from  the  smell  of  the  oil  enduring  for 
some  time  afterwards.  By  enclosing  the  greasy  spot  between  folds  of  blotting  pa- 
per, and  applying  a  hot  smoothing  iron  to  the  paper,  the  oil  is  drawn  up  hy  capillary 
attraction;  and  the  more  readily  if  its  bulk  and  fusibility  be  previously  increased  by 
the  addition  of  an  essential  oil. 

It  is  by  capillary  attraction  that  moistened  clay,  in  drying,  draws  grease  out  of  a 
floor;  and  in  like  manner  leather  is,  by  previous  moistening,  made  to  take  up  oil, 
applied  to  it  superficially,  as  the  moisture  is  vaporized. 

Strong  alcohol,  especially  when  hot,  may  be  used  to  extract  grease;  also  aqua 
ammonia,  or  the  alcohol  and  ammonia,  without  being  heated,  may^be  united  for  this 
purpose,  with  still  greater  effect. 


432  ORGANIC  CHEMISTRY. 

hol,  and  ability  to  unite  in  all  proportions  with  volatile 
oils,  cannot  be  distinguished  from  them.  But  as  to  com- 
position there  is  no  analogy;  while  between  fixed  oils  and 
certain  ethers,  both  consisting  of  acids  in  union  with  an 
oxidized  compound  radical,  the  analogy  in  composition  is 
perfect. 

5079.  Volatile  oils  may  be  arranged  into  several  sets, 
or  classes,  according  to  their  origin. 

,5080.  1st.  Oils  directly  produced  by  vegetables  and  ex- 
tricated by  pressure,  heat,  or  solvents,  so  as  to  be  obtained 
in  their  native  state. 

5081.  2d.  Oils  which  result  from  the  reaction  of  the 
proximate  elements  of  vegetation,  as  the  oil  of  bitter  al- 
monds, of  spirea,  and  black  mustard  seed. 

5082.  3d.  Oils  which  have  been  produced  by  the  reac- 
tion of  their  ultimate  elements  during  destructive  distilla- 
tion, or  by  the  reaction  of  organic  substances  with  chemical 
agents.    Among  these  we  may  place  mineral  naphtha,  coal 
naphtha,  kreosote,  camphogen,  caoutchouchine,  and  a  great 
variety  of  liquids  resulting  from  the  exposure  of  bituminous 
or  resinous  substances  to  heat. 

5083.  It  must  be  evident  that  for  almost  every  flower 
and  fruit,  as  well  as  many  leaves  and  roots,  there  is  an 
appropriate  odour;  and  moreover,  that  in  some  instances, 
as  in  that  of  the  orange,  different  parts  of  the  same  plant 
will  be  productive  of  different  odours.     In  all  cases  where 
such  odours  are  observed,  we  have  good  reason  to  infer 
the  existence  of  a  peculiar  volatile  oil.    It  is  plainly  among 
the  wonders  of  the  creation,  that  such  diversity  of  proper- 
ties should  be  found  in  substances  of  which  a  great  number 
consist,  as  far  as  chemical  skill  can  determine  the  question, 
of  only  two  ultimate  elements,  carbon  and  hydrogen,  which 
are  severally,  when  isolated  and  pure,  inodorous.     Many 
different  kinds  of  non-oxygenated  volatile  oils  are  com- 
posed of  these  elements  in  the  same  proportion. 

5084.  The  volatile  oils  generated  by  vegetation,  are  gene- 
rally extricated  by  subjecting  the  substance  containing  them 
to  distillation  with  water,  when,  agreeably  to  the  Daltonian 
law  (229)  that  one  vapour  acts  as  a  vacuum  to  another,  a 
portion  of  the  oil  comes  over,  bearing  the  same  ratio  to 
the  aqueous  steam,  that  the  tension  of  the  one  vapour  in 
vacuo  would  have  to  that  of  the  other.     Thus,  supposing 
that  at  212°  the  oil  would  boil,  when  within  the  containing 


OF  VOLATILE  OILS.  433 

vessel  the  pressure  should  be  equal  only  to  five  inches  of 
mercury,  while  the  aqueous  steam  may  be  formed  under  a 
pressure  of  30  inches,  then  the  vapour  which  would  come 
over  when  they  are  both  subjected  to  distillation  at  212°, 
would  be  a  mixture  of  five  volumes  of  steam  for  one  of 
vaporized  oil. 

5085.  Some  oils  are  obtained  by  expression,  those  of  the 
skins  of  oranges  and  lemons  for  instance,  while  others  are 
procured  by  maceration  in  fixed  oils  (5075),  which,  when 
inodorous,  may  be  used  as  a  vehicle  for  their  subsequent 
application,  or  may  be  made  to  give  them  up  by  distillation 
with  water,  as  already  mentioned. 

5086.  Ether  may  be  advantageously  employed  to  isolate 
volatile  oils.     It  is  an  excellent  solvent  of  them,  and  when 
quite  pure  evaporates,  leaving  them  unchanged. 

5087.  When  distilled  or  evaporated  without  protection, 
there  is  a  reaction  between  them  and  atmospheric  oxygen, 
or  other  impurities,  by  which  more  or  less  resin  is  gene- 
rated.    Hence,  when  used  as  solvents  for  resins,  they  do 
not  dry  off  as  well  as  alcohol  or  ether.    The  affinity  which 
oil  of  turpentine  has  for  some  resins,  common  resin  among 
others,  is  so  great  that  mere  evaporation  in  the  air  never 
causes  its  entire  removal  from  them. 

5088.  By  agitation  with  diluted  sulphuric  acid  with  al- 
cohol, or  preferably  with  a  solution  of  chloride  of  calcium 
in  alcohol,  the  resin  may  be  removed  from  an  essential  oil, 
as  is  shown  by  the  colour  imparted  to  the  detergent  liquid, 
and  the  diminution  of  that  of  the  oil.* 

5089.  According  to  Graham,  the  odour  of  essential  oils 
is  due  to  oxidizement,  since  no  oil  has  any  smell  imme- 
diately after  its  distillation,  in  an  atmosphere  of  carbonic 
acid.     This  may  afford  an  explanation  of  a  fact,  which  I 
have  long  noticed,  that  an  alcoholic  solution  of  a  volatile 
oil  has  more  odour  than  the  oil  when  isolated.    Hence  the 
importance  of  keeping  such  substances  in  well  closed  bot- 
tles must  be  evident. 

5090.  The  inflammation  of  an  essential  oil  by  concen- 
trated nitroso-nitric  acid,  has  been  shown.     A  compound 
results  from  its  reaction  with  them,  when  inflammation 

*  A  small  proportion  of  alcohol,  and  also  of  water,  is  liable  to  be  held  by  essential 
oils.  This  may  be  removed  by  chloride  of  calcium.  In  fact,  this  chloride  has  been 
recommended  lately  to  be  used,  in  order  to  detect  the  falsification  of  such  oils  by  a!- 
cohol.  If,  on  adding  a  lump  of  anhydrous  chloride  to  the  oil,  no  change  in  the  sur- 
face is  perceived,  the  oil  may  be  considered  as  free  from  both  alcohol  and  moisture. 


434  ORGANIC  CHEMISTRY. 

does  not  ensue,  which  has  not  been  well  examined.  With 
iodine  some  of  the  volatile  oils  have  an  explosive  reac- 
tion. 

5091.  Volatile  oils,  at  a  high  temperature,  dissolve  much 
sulphur,  and  a  small  proportion  of  phosphorus,  and  are  in 
some  degree  soluble  in  several  vegetable  acids,  as  for  in- 
stance, acetic,  oxalic,-  succinic,  and  the  oily  acids.     With 
the  exception  of  oil  of  cloves,  of  cinnamon,  and  of  cedar 
wood,  they  do  not  form  compounds  when  heated  with 
alkaline  or  earthy  bases.      They  are  not  susceptible  of 
saponification.    When  triturated  with  sugar  they  are  more 
ready  to  mingle  with  water.     They  are  excellent  solvents 
of  the  fixed  oils,  fat,  spermaceti,  wax,  and  generally  for  re- 
sins.    Agreeably  to  my  observations,  the  volatile  oils,  es^ 
pecially  those  containing  oxygen,  absorb  sulphurous  acid 
copiously;  and  even  when  washed  with  liquid  ammonia,  do 
not  give  all  the  elements  of  the  acid,  but  retain  it,  proba- 
bly in  the  state  of  hipposulphuric  acid. 

5092.  The  density  of  native  essential  oils  varies  between 
0.750  as  in  the  case  of  that  of  coriander,  and  1.096  in  the 
instance  of  oil  of  sassafras. 

5093.  From  caoutchouc,  or  gum  elastic,  an  oil  has  been 
obtained  of  the  density  of  .670,  which  is  much  less  than 
that  of  any  native  oil  evolved  from  vegetables. 

5094.  Volatile  oils,  in  general,  absorb  six  or  eight  times 
their  volume  of  ammoniacal  gas ;  but  the  oil  of  lavender 
absorbs  47  times  its  volume. 

5095.  Oil  of  turpentine  absorbs  one-fifth  of  its  volume 
of  carbonic  acid;  nearly  double  its  volume  of  carbonic 
oxide;  twice  its  volume  of  olefiant  gas;  27  per  cent,  of 
nitrous  oxide,  and  five  times  its  volume  of  cyanogen. 

5096.  Volatile  oils  are  converted  into  resins  by  those 
metallic  oxides  which  are  readily  deoxidized :  also  by  the 
chlorides  of  tin  and  of  antimony.     What  is  called  Star- 
key's  soap,  obtained  by  triturating  oil  of  turpentine  with 
an  alkali,  is  a  combination  of  a  resin,  produced  during  the 
process,  with  the  alkali  employed. 

Volatile  Oils  containing  Sulphur  as  an  ultimate  Element. 

5097.  The  presence  of  sulphur  in  the  volatile  oils,  which 
come  under  the  preceding  designation,  forms  a  remarkable 
exception  to  the  prevailing  composition  of  such  oils.     The 


VOLATILE  OIL  OF  MUSTARD.  435 

volatile  oils  of  black  mustard  seed,  of  horse-radish,  of 
onions,  of  asafcetida,  of  water  pepper,  of  hops,  and  some 
others,  contain  sulphur. 

Volatile  Oil  of  Mustard,  C8  H5  NS2. 

5098.  This  oil  is  obtained,  by  distillation  with  water, 
from  the  black  mustard  seed,  being,  it  is  alleged,  the  result 
of  the  reaction  of  an  albuminous  constituent  called  myro- 
zine,  and  an  acid  denominated  rnyronic  acid.     Volatile  oil 
of  mustard  is  colourless,  heavier  than  water,  affecting  the 
olfactory  nerves  so  painfully  as  to  induce  tears,  and  pro- 
ducing inflammation  and  blisters  on  contact  with  the  skin. 
Its  boiling  point  is  289.4.     When  inflamed,  it  gives  fumes 
of  sulphurous  acid.     By  distillation  from  hydrated  oxide  of 
lead,  it  is  deprived  of  its  sulphur,  and  resolved  into  ammo- 
nia, and  a  crystalline  substance  called  sinapoline. 

5099.  From  the  formula  it  will  be  seen  that  this  oil  con- 
tains one  atom  of  nitrogen,  as  well  as  two  atoms  of  sul- 
phur.    From  the  contact  of  this  oil  with  ammonia  in  a 
well  closed  phial,  a  crystalline  compound  is  formed,  sup- 
posed to  be  an  amiduret.    Of  this  the  formula  is  C8  H5  NS2 
+  NH2. 

5100.  The  remarks  which  were  made  respecting  the  in- 
expediency of  treating  of  fixed  oils  in  detail,  apply  equally 
in  the  case  of  the  volatile  oils. 

5101.  For  information  respecting  their  medical  proper- 
ties, their  botanical  relations,  and  the  processes  of  extri- 
cating them,  where  they  are  among  the  articles  of  the  ma- 
teria  medica,  reference  may  be  had  to  the  United  States 
Dispensatory. 

5102.  It  has  been  mentioned  that  there  are  two  classes 
of  oils ;  one  containing  oxygen,  the  other  devoid  of  that 
element.     The  following  tables  of  the  more  important  vo- 
latile oils,  with  and  without  oxygen,  are  given  by  Kane. 


56 


436 


ORGANIC  CHEMISTRY. 
Volatile  Oils  containing  Oxygen. 


Plant  yielding  the  Oil. 

Sj?-.  S^- 
as  Liquid. 

Boiling 
Point. 

Formula. 

Sp.  gr. 
of  Vapour. 

Cajeput        .... 

0.927 

347° 

C10  H9  Q 

Lavender   .... 

0.896 

397° 

C15  H14  O 

Rosemary       .     .     . 

0.897 

365° 

C45   R38   Q3 

Pennyroyal     .     .     . 

0.925 

395° 

C10  H8  O 

Camphor  tree       .     . 

0.910 

C30  H16  O 

Valerian     .... 

518° 

C20  H13  O 

Spearmint       .     .     . 

0.914 

C35  H28  O 

Marjoram  .... 

0.867 

354° 

C50  H40  0 

Asarum      .... 

C16  H9  O3 

Fennel       .... 

0.997 

C30  H13  Oa 

Anise    

C20  H13  O3 

Peppermint     .     .     . 

0.902 

C*i  H30  O3 

Rue       

0.837 

446° 

C28  H38  O3 

7690 

Olibanum  .... 

0.866 

323° 

C35  H28  O 

0.860 

418° 

C30  H1S  O3 

5094 

Volatile  Oils  devoid  of  Oxygen. 


Plant  yielding  the 
Oil. 

Sp.  gr. 
as  liquid. 

Boiling 
Point. 

Formula. 

Sp.  gr. 
as  Vapour. 

Circular  Polarizing 
Power. 

Citron    .  < 

0.847 

343° 

Q}  c  o 

_C    0  Xj 

ID   O   fcT 

.S  -c  ^* 

4-  80°  9,  right 

Copaiva 

0.878 

473° 

CD  -^          ,** 

4-  34°  2,  left 

Parsley 

410° 

«  2  .a*™ 

«,  "§    S 

Juniper 

0.839 

311° 

"S  5  T-J  O 

'o  ^ 

—  3°  5,  left 

Savine  . 

315° 

O    O    ;/;    c3 

0    2    0§ 

Cubebs  . 

0.929 

J^  £  c 

"    0  ^  ^ 

—  40°  l,left 

Black  Pepper  . 

£  a-  £ 

+^    c«    X!    o 

«    0.  II 

Bergamotte 

_    73    <D  « 

_.     >     CO 

4-  29°  3,  right 

Turpentine 

0.864 

315° 

—  43°  3,  left 

5103.  Generally,  essential  oils  containing  oxygen  may 
be  separated  into  an  acid  and  an  oil  destitute  of  oxygen, 
by  reaction  with  fused  hydrate  of  potash.  Thus,  from  oil 
of  valerian,  valerianic  acid  has  been  obtained,  and  an  oil 
which,  absorbing  oxygen  rapidly,  is  converted  into  com- 
mon camphor.*  Oil  of  cumin,  by  similar  treatment,  yields 
cuminic  acid,  which  is  analogous  with  benzoic  acid,  and  is 
conjectured  to  have  a  relation  to  a  peculiar  compound  ra- 
dical, cumyl,  analogous  to  that  which  the  acid  last  men- 
tioned, has  to  benzule  or  benzyl. 


Gerhardt  and  Cahours. 


OILS  CONTAINING  OXYGEN.  437 

5104.  The  composition  of  all  the  essential  oils  free  from 
oxygen,  may  be  represented  by  C5  H4,  their  formulas  being 
multiples  of  these  numbers.     Turpentine  has  the  formula 
of  C20  H16;  cubebs  C15  H12;  and  the  rest  C10  H8. 

5105.  Kane  observes,  that  an  examination  of  the  tables 
above  given,  will  make  it  appear  that  all  essential  oils  con- 
sist of  multiples  of  C5  H4  with  oxygen  and  water. 

5106.  Of  Oil  of  Turpentine. — This  is  the  cheapest,  and 
hence  by  much  the  most  used  of  all  the  volatile  oils,  and 
furnishes  a  good  exemplification  of  an  essential  oil  devoid 
of  oxygen.     When  pure,  it  is  as  colourless  and  limpid  as 
water.     Its  volatility,  inflammability,  hot  pungent  taste, 
and  disagreeable  smell,  recalling  that  of  camphor,  are  well 
known.     At  72°  F.  its  density  is  .86.     Its  boiling  point 
is  above  300°.     In  water  it  is  but  minutely  soluble,  and 
cold  alcohol  only  takes  up  about  one-seventh  of  its  bulk. 
When  hot,  it  takes  up  a  larger  proportion,  which  is  de- 
posited by  refrigeration.     As  found  in  commerce,  oil  of 
turpentine  is  said  to  contain  oxygen,  whereas,  in  truth, 
it  holds  a  resin,  in  which  that  element  is  a  constituent,  and 
from  which  it  may  be  freed  by  distillation  with  water,  or 
by  agitation  either  with  alcohol,  with  diluted  sulphuric 
acid,  or  with  an  alcoholic  solution  of  chloride  of  calcium. 
From  the  diversity  of  the  two  compounds  formed  with  it 
by  chlorohydric  acid,  there  cannot  be  a  doubt  that  it  con- 
sists of  two  volatile  oils  differing  but  little  in  composi- 
tion.   These  are  alleged  to  give  rise  to  two  different  resins, 
found  in  the  rosin  which  is  associated  with  it  in  its  native 
state.*    See  artificial  camphor,  camphene,  &c.  5112,  5114. 

*  Recently  distilled,  and  after  being  carefully  purified  of  any  resinous  matter,  oil 
of  turpentine  has  been  found  capable,  lately,  of  being  burned  in  Argand  lamps  of  a 
peculiar  construction,  and  of  giving  a  light  much  more  intense  than  that  produced 
by  fixed  oil,  wax,  or  gas. 

In  fact,  the  excess  of  carbon  which  makes  the  flames  of  volatile  oils  too  fuliginous 
for  use,  as  subjected  to  combustion  in  ordinary  lamps,  is,  in  the  case  in  point,  the 
cause  of  the  superior  light,  as  it  is  well  known  that  the  intensity  of  the  illumination 
is  as  the  quantity  of  carbon  oxidized  in  a  given  space. 

The  odour  of  oil  of  turpentine,  and  a  flocculent  deposition  of  carbon,  notwithstand- 
ing that  there  is  no  apparent  association  of  such  matter  with  the  flame;  also  the  ad- 
ditional danger  in  case  of  fire  resulting  from  the  presence  even  of  a  small  quantity 
of  a  volatile  inflammable  liquid,  are  the  great  objections  to  the  general  use  of  this 
cheap  and  brilliant  method  of  illumination.  For  streets  and  light-houses,  where  gas 
cannot  be  employed  advantageously,  a  resort  to  this  process  may  be  highly  expe- 
dient. 

The  principles  already  adverted  to,  by  which  a  liquid  in  contact  with  matter  in  a 
state  of  vaporization,  will  be  vaporized  proportionably  to  the  tension  of  the  vapour 
which  it  would  form  in  vacuo  at  that  temperature,  are  brought  into  play  when  a  so- 
lution of  turpentine  in  alcohol  is  burned  in  lamps  of  an  appropriate  form.  This  con- 
trivance is  founded  upon  experiments  made  by  myself  more  than  twenty  years  ago, 


438  ORGANIC  CHEMISTRY. 

Of  Camphor. 

5107.  Camphor,  C20  H16  O2,  or  C20  H14  +  2HO,  seems  to 
have  a  relation  to  the  volatile  oils,  resembling  that  of  stea- 
rine  or  spermaceti  to  the  fixed  oils,  being  a  species  of  con- 
crete oxidized  volatile  oil.     It  is  represented  as  the  stea- 
ropten  of  the  oil  of  camphor.    Its  consistency,  smell,  taste, 
solubility  in  alcohol,  in  ether,  and  in  the  fixed  and  volatile 
oils;  also  its  insolubility  in  water,  and  susceptibility  of 
volatilization  or  evaporation  in  the  air,  are  well  known. 
Camphor  fuses  at  347°,  boils  at  399.2°.     Its  density  in  the 
solid  state,  as  compared  with  that  of  water,  0997 ;  in  the 
state  of  vapour,  as  compared  with  air,  5317. 

5108.  By  repeated  distillations  with  anhydrous  phos- 
phoric acid,  it  loses  two  atoms  of  water,  and  is  reduced  to 
the  state  of  a  colourless  liquid  hydruret  of  carbon,  C20  H14, 
of  the  density  of  .861  at  57°,  being  denominated  by  Du- 
mas, its  discoverer,  camphogen.    Camphogen  is  analogous 
to  benzole  or  naphthaline. 

5109.  Liquid  camphor,  C20  H16  O1,  is  a  product  of  the 
same  tree  as  concrete  camphor,  and  contains  a  more  liquid 
portion,  and  less  liquid  portion.    The  former,  the  elaopten, 
differs  from  concrete  camphor  in  containing  only  half  as 
much  oxygen.     Its  density  is  less  than  that  of  the  solid 
camphor.     In  composition,  the  latter  differs  from  oil  of 
turpentine  only  in  the  presence  of  two  atoms  of  oxygen; 
liquid  camphor  in  the  presence  of  one  atom  of  the  same 
element. 

5110.  An  interesting  account  of  this  substance  will  be 
found  in  the  United  States  Dispensatory. 

5111.  Other  volatile  oils,  besides  that  of  the  camphor 
tree,  yield  stearopten  analogous  to  camphor.     Of  such  oils 
Kane  gives  the  following  table: — 

when  I  used  a  mixture  of  six  parts  of  alcohol,  and  one  of  oil  of  turpentine,  in  an  Ar- 
gand  lamp. 

Subsequently,  however,  on  being  consulted,  I  objected  to  the  use  of  the  contri- 
vance on  account  of  the  danger  arising  from  its  liability  to  inflame.  Experience  has 
shown,  by  many  melancholy  disasters,  that  this  counsel  was  correct. 


OF  ARTIFICIAL  CAMPHOR. 


439 


Plant  giving  the 
Camphor. 

sTP-.gr.- 
as  Liquid. 

Melting 
Point. 

Boiling 
Point. 

Sp.  gr. 
of  Vapour. 

Formula. 

Rose  (Otto)      . 

77° 

550° 

CH 

Parsley       .     . 

70° 

552° 

c«  H?  0* 

Iris  Florentina 

C4H*O 

Elecampane     . 

108° 

C7H5O 

Asarum      .     . 

104° 

530° 

C18  Hll  Q4 

Fennel        .     . 

1.014 

68° 

428° 

Q20  H13  Q3 

Anise     .     .     . 

64° 

430° 

5680 

C30  H13  Oa 

Peppermint 

91° 

406° 

5455 

C31  H20  O3 

Cubebs  .     .     . 

C18  H14  O 

Turpentine 

1.057 

302° 

311° 

C*o  Hao  o* 

"  On  comparing  these  formulae  with  those  of  the  corresponding  oils,  it  is  seen  that 
the  camphors  arise  from  very  various  causes ;  in  some  cases  they  are  isomeric  with 
the  oils,  in  others  oxides  of  them,  and  in  others  hydrates;  thus,  the  camphor  of  tur- 
pentine may  be  formed  at  will,  by  agitating  the  oil  with  water  and  then  exposing  it 
to  cold;  the  hydrate  crystallizes  out  in  colourless  prisms,  sometimes  of  great  size. 

"  The  peppermint  camphor  has  been  found  to  yield,  by  the  action  of  reagents,  a 
series  of  compounds.  Thus,  by  the  action  of  glacial  phosphoric  acid,  or  of  oil  of 
vitriol,  a  light  oil  was  obtained,  having  the  formula  C21  H18,  which  is  termed  men- 
then.  By  the  action  of  chlorine,  a  thick  heavy  liquid  is  produced,  C21  H14  Cl6  O2. 
By  nitric  acid,  menthen  yields  a  heavy  oily  liquid,  C21  H18  O9,  which  possesses  acid 
properties;  and  with  chlorine,  menthen  yields  a  syrupy  yellow  liquid,  having  the 
formula  C^  H*  CIV 

Artificial  Camphor. 

5112.  If  one  hundred  parts  of  oil  of  turpentine,  refrige- 
rated by  snow  and  salt,  be  saturated  with  chlorohydric 
acid  gas,  by  means  of  an  impregnating  apparatus,  a  quan- 
tity of  the  gas,  equal  to  about  one-third  of  the  weight  of 
the  turpentine,  is  absorbed.     Meanwhile  the  turpentine  is 
changed  into  a  soft  crystalline  mass,  from  which,  allowing 
it  to  drip  for  some  days,  about  twenty  parts  of  a  colour- 
less acid  liquor  are  obtained,  charged  with  many  crystals, 
and  one  hundred  parts  of  a  white,  granular,  crystalline  sub- 
stance, which  so  much  resembles  camphor  in  odour  and 
volatility,  that  it  has  received  the  same  appellation. 

5113.  Artificial  camphor  is  lighter  than  water.     It  does 
not  redden  litmus.     It  may  be  sublimed,  but  not  without 
partial  decomposition.     If  passed  through  an  incandescent 
tube,  it  is  resolved  into  its  constituents.    It  dissolves  in  al- 
cohol, and  is  precipitated  from  it  by  water  unchanged. 
Chlorine  is  disengaged  from  it  by  nitric  acid.     This  sub- 
stance has  been  analyzed  both  by  Dumas  and  Oppermann. 
According  to  the  former  chemist,  it  is  composed  of  one 
volume  of  chlorohydric  acid  united  to  one  volume  of  a 


1 
I 


440  ORGANIC  CHEMISTRY. 

compound,  formed  of  ten  atoms  of  carbon  and  eight  of 
hydrogen,  and  consequently  identical  in  composition  with 
pure  oil  of  turpentine. 

Of  Camphene  or  Camphelene,  and  Terebene. 

5114.  From  artificial  camphor,  by  subjection  to  the  distillatory  process 
with  quick-lime,  an  oil  separates,  called,  by  Dumas,  camphene,  by  others, 
camphelene.  This  oil  is  identical  in  composition  with  pure  oil  of  turpen- 
tine, and  differs  from  it  so  little  in  properties,  that  were  it  not  that  the  latter 
has  a  power  of  causing  a  pencil  of  polarized  rays  to  turn  to  the  left,  of 
which  power  the  former  is  devoid,  one  could  not  be  distinguished  from  the 
other.  The  liquid  from  which  the  artificial  camphor  crystallizes,  has  the 
smell  of  camphor  no  less  than  the  crystalline  portion,  and  consists  of  nearly 
the  same  ultimate  elements,  united  to  chlorohydric  acid.  It  has  a  relation 
to  artificial  camphor  like  that  which  the  eleapten  of  a  volatile  oil  bears  to 
the  stearopten.  When  this  liquid  artificial  camphor  is  distilled  with  sul- 
phuric acid  at  as  low  a  heat  as  possible,  an  oil  is  obtained,  called  terebene, 
which  is,  like  camphene,  devoid  of  the  power  of  causing  any  rotation  in  po- 
larized rays.  Yet  either  terebene  or  camphene,  by  uniting  again  with  chlo- 
rohydric acid,  may  regenerate  each  the  kind  of  artificial  camphor  from 
which  it  was  evolved,  and  in  this  respect  they  differ  from  each  other,  while 
differing  from  the  pure  native  oil  as  already  stated.  Yet,  by  combining 
with  chlorine,  both  camphene  and  terebene  acquire  a  power  of  causing,  in 
polarized  light,  a  rotation  in  a  direction  the  opposite  of  that  produced  by  the 
native  oil  of  turpentine  (4052).  v 

Of  Kreosote. 

5115.  This  name  has  been  given  to  an  essential  oil,  to 
which  allusion  has  been  above  made,  as  one  of  the  pro- 
ducts of  the  destructive  distillation  of  vegetable  matter.    It 
is  represented  as  highly  interesting  and  important,  on  ac- 
count of  its  efficacy  as  a  medicine,  and  in  preserving  meat; 
being  in  fact  considered  as  the  principle  to  which  pyrolig- 
neous  acid  and  wood  smoke  are  indebted  for  their  antisep- 
tic powers,  and  tar-water  for  its  medicinal  virtues.* 

5116.  Kreosote  is  elaborated  either  from  crude  pyrolig- 
eous  acid,  or  from  wood  tar,  by  a  series  of  distillations, 

and  subjection  to  different  agents. 

5117.  Besides  its  activity  in  medicine,  kreosote  is  al- 
leged to  have  energetic  powers  as  a  chemical  agent.    It  is 
an  oleaginous,  colourless,  transparent,  and  highly  refract- 
ing liquid.     It  has  the  smell  of  crude  pyroligneous  acid,  or 
of  smoked  meat,  and  its  taste  is  caustic  and  burning.     To 

*  The  antiseptic  power  of  oil  of  cloves,  and  still  more  that  of  oil  of  cinnamon,  are 
equal  to  those  of  kreosote,  agreeably  to  my  experiments  made  with  meat  or  cream. 
A  few  drops  of  cinnamon  oil  added  to  a  paste  of  gum  tragacanth,  will  prevent,  for 
months,  the  fetor  which  otherwise  is  soon  acquired. 


OF  ESSENTIAL  OILS  WHICH  ARE  HYDRURETS.  441 

the  touch  it  is  a  little  greasy,  and  its  consistency  is  similar 
to  that  of  the  oil  of  almonds.  It  is  rather  heavier  than 
water,  being  of  the  specific  gravity  of  1.037.  It  boils  at 
397°. 

5118.  Kreosote  is  devoid  of  acid  or  alkaline  reaction. 
With  water  it  forms  two  combinations — one  a  solution  of 
one  part  xof  kreosote  in  four  hundred  of  water,  the  other  a 
solution  of  one  part  of  water  in  ten  of  kreosote.     It  unites 
in  all  proportions  with  alcohol,  ether,  and  naphtha,  and  is 
capable  of  dissolving  a  large  quantity  of  iodine  and  phos- 
phorus, and  likewise  sulphur,  especially  when  assisted  by 
neat.     Agreeably  to  Thenard,  the  composition  of  kreosote 
is  expressed  by  the  formula,  C14  H9  O2. 

Of  Essential  Oils  which  are  Hydrurets. 

5119.  Among  the  oils  which  may  be  called  hydrurets, 
are  the  hydruret  of  benzule  or  oil  of  bitter  almonds;  an 
oily  hydruret  existing  in  the  commercial  oil  of  cinnamon 
or  cassia,  called  hydruret  of  cinnamyl;  the  oil  of  spirea 
ulmaria  or  hydruret  of  salycyl;  and  the  hydruret  of  cumyl, 
derived  from  the  oil  of  cumin.     Of  the  three  first  men- 
tioned oils,  some  account  has  been  given  in  treating  of 
their  radicals ;  and  to  the  hydruret  of  cumyl,  allusion  was 
made  in  paragraph  5103.     I  do  not,  however,  deem  it  ex- 
pedient to  give  any  details  here  respecting  any  of  these 
oils,  excepting  the  hydruret  of  benzule.     Of  this  I  shall 
treat  for  the  purpose  of  exemplification. 

Of  the  Hydruret  of  Benzule,  or  Oil  of  Bitter  Almonds. 

5120.  The  formula  of  this  hydruret  is  O4  H5  O3  -f  H,  or  BZ  +  H.    By 
distilling  bitter  almonds,  or  the  leaves  of  cherry  laurel,  with  water,  a  vola- 
tile product  comes  over,  consisting  of  a  mixture  of  the  hydruret  of  benzule, 
of  benzoic  acid,  of  gum  benzoin,  and  cyanhydric  acid.     In  order  to  extri- 
cate the  hydruret  from  this  mixture,  a  second  distillation  is  requisite,  with 
the  previous  addition  of  chloride  of  iron,  hydrate  of  lime,  and  sufficient  water 
to  liquefy  the  whole.     Under  these  circumstances,  the  oil  may  be  distilled, 
accompanied  by  water,  which  may  be  separated  by  the  usual  means,  and 
subsequent  agitation  with  chloride  of  calcium. 

5121.  Properties. — This  hydruret  is  colourless  and  transparent,  refract- 
ing light  strongly,  being  endowed  with  a  strong  odour  like  that  of  cyanhy- 
dric acid,  and  a  hot  taste.     Its  specific  gravity  is  1.043;  its  boiling  point 
356°.     It  is  soluble  in  thirty  parts  of  water,  and  in  alcohol  in  proportion. 
Its  vapour  may  be  transmitted  through  a  red-hot  tube  without  decomposi- 
tion.    It  burns  with  a  white,  though  smoky  flame.     By  absorbing  two 
atoms  of  atmospheric  oxygen,  one  to  unite  with  an  atom  of  hydrogen,  the 
other  to  take  its  place,  this  hydruret  is  converted  into  benzoic  acid.     Sub- 


442  ORGANIC  CHEMISTRY. 

jected,  at  a  high  temperature  in  close  vessels,  to  hydrate  of  potash,  it  forms 
a  benzoate  of  that  base  by  absorbing  the  oxygen,  and  liberating  the  hydro- 
gen of  an  atom  of  water. 

5122.  The  hydruret  of  benzule  undergoes  no  change  by  being  in  contact 
with  aqueous  solutions  of  caustic  alkalies  or  earths,  but,  while  thus  situated, 
a  few  drops  of  cyanhydric  acid  will  enable  crystals  of  benzoin  to  be  gene- 
rated. 

5123.  By  contact  with  chlorine  or  bromine,  the  hydruret  of  benzule  is 
converted  into  chloride  or  bromide,  its  hydrogen  being  simultaneously  con- 
verted into  chlorohydric  or  bromohydric  acid,  by  uniting  with  one  or  the 
other  of  those  elements. 

5124.  An  iodide  of  benzule  can  be  obtained  by  the  reaction  of  the  chlo- 
ride of  this  compound  radical  with  the  iodide  of  potassium ;  in  like  manner 
a  sulphide,  by  the  distillatory  reaction  of  a  chloride  with  the  sulphide  of 
lead;  and  a  cyanide,  by  substituting  a  cyanide  of  mercury  and  resorting  to 
the  same  means. 

Of  the  Amiduret  of  Benzule  or  Benzamide,  BZ  NH3. 

5125.  From  the  preceding  formula  it  must  be  evident  that  the  compound, 
of  which  the  name  is  above  given,  consists  of  benzule,  and  the  compound 
radical,  amide. 

5126.  This  amiduret  arises  from  the  reaction  of  the  chlorides  of  the  same 
radical  with  dry  ammonia.     It  is  likewise  evolved  by  the  reaction  of  hip- 
puric  acid  with  the  peroxide  of  lead. 

5127.  Amiduret  of  benzule  crystallizes  in  right  rhomboidal  pearly  prisms 
or  tables.     A  hot  concentrated  solution  by  refrigeration,  yields  a  soft  mass 
of  very  fine  crystalline  needles,  which  are  gradually  transformed  into  broad 
colourless  laminae.     These  crystals  melt  at  239°  into  a  colourless  liquor, 
and  at  higher  temperatures  are  susceptible  of  forming  an  inflammable  va- 
pour.    They  are  soluble  either  in  water,  alcohol,  or  ether. 

5128.  Water  being  present,  alkalies  or  acids  resolve  this  amiduret  into 
ammonia  and  benzoic  acid.     On  being  heated  with  anhydrous  baryta,  a 
benzoate  of  this  base  is  produced,  with  a  disengagement  of  ammonia,  much 
heat,  and  the  volatile  oil  called  benzole.     Similarly  treated  with  potassium, 
a  cyanide  of  this  metal  results,  with  the  evolution  of  an  oleaginous  aromatic 
liquid  of  a  slightly  sweet  taste.     The  hydruret  of  benzule  unites  also  with 
anhydrous  formic  acid,  generating  a  compound  acid  called  formobenzolic 
acid ;  also  with  benzoic  acid,  formingxwhat  is  by  Liebig  termed  a  benzoate 
of  the  hydruret  of  benzule. 

Of  Resins. 

5129.  Resin  is  now  the  generic  name  of  a  class  of  bo- 
dies, of  which  common  resin  or  rosin  is  an  exemplification, 
having  had  its  name  extended  to  the  class  in  consequence 
of  their  analogy  with  it.    On  this  account,  English  writers 
have  latterly  used  the  word  resin,  generally  employing  the 
word  rosin  as  the  name  for  the  substance  which  formerly 
was  designated  either  as  resin  or  rosin.    In  pharmacy,  rosin 
is  also  known  as  colophony  or  colophonium;  especially  on 
the  continent  of  Europe. 


OF  RESINS.  443 

5130.  Resins  are  found  in  vegetables  and  in  the  fossil 
state,  as  in  the  instance  of  amber  and  asphaltum ;  but  in 
every  case,  are  considered  as  having  been  originally  the 
products  of  vegetation. 

5131.  In  vegetables,  resins  exist  more  or  less  in  combi- 
nation with  essential  oils;  and  I  believe  them  to  be  gene- 
rally produced  by  the  reaction  of  such  oils  with  oxygen. 
It  has  been  mentioned  that,  when  distilled  per  se,  almost 
every  volatile  oil  is  liable  to  be  partially  converted  into  a 
resinous  substance,  which  does  not  come  over.     It  is  also 
true,  that  any  resin,  exposed  to  destructive  distillation,  gives 
rise  to  more  or  less  pyrogene  oils  of  the  volatile  kind,  as 
well  as  carburetted  hydrogen,  and  carbonaceous  deposi- 
tions, and  residues. 

5132.  In  many  cases,  as  in  that  of  the  turpentine  of 
commerce,  the  compound  formed  by  the  resin  and  the 
volatile  oil  with  which  it  is  naturally  associated,  is  suffi- 
ciently liquid  to  flow  from   incisions   made   through   the 
bark  and  sap  wood.     It  is  thus  that  the  copious  supply  of 
turpentine  found  in  commerce,  is  obtained  from  the  long- 
leaved  pine  of  the  Carolinas. 

5133.  Another  portion  of  resinous  matter,  expelled  by 
fire,  forms  the  tar  of  commerce.     This  contains  some  re- 
markable volatile  compounds  generated  by  heat,  called 
paraifine,  eupion,  and  kreosote.    The  former  is  a  concrete 
oil,  the  others  liquid.     Tar  also  contains  acetic  acid  in 
combination  with  the  several  peculiar  resins,  called  pyre- 
tene,  or  pyrogene  resins,  by  Berzelius. 

5134.  As  the  expulsion  of  resinous  matter  by  the  tar- 
producing  process  destroys  the  peculiar  properties  of  re- 
sins, I  believe  it  is  not  resorted  to  in  obtaining  resins  in 
other  cases.     More  valuable  resins,  which  do  not  sponta- 
neously exude,  are  generally  extracted  by  digesting  the 
vegetable  product  containing  them  in  alcohol.     From  the 
alcoholic  solution,  when  it  takes  up  other  substances,  the 
resin  is  precipitated  by  water.* 


*  The  celebrated  varnish  of  the  island  of  Japan  exudes  from  the  rhus  vernix, 
which  is  among  the  forest  trees  of  the  United  States,  being  notorious  for  its  poison- 
ous influence  on  some  persons,  while  to  others  comparatively  harmless.  The  active 
principle  to  which  its  poisoning  power  is  due,  would  be  a  worthy  object  of  investiga- 
tion by  any  one  not  susceptible  of  the  injurious  effects  alluded  to.  In  the  art  of  ja- 
panning in  this  country  and  in  Europe,  other  substances  are  made  to  imitate  the 
effect  of  the  real  Japan  varnish,  named  from  the  country  in  which  it  is  employed. 
57 


444  ORGANIC  CHEMISTRY. 

5135.  Resins  are  all  insoluble  in  water,  and  for  the  most 
part,  directly  or  indirectly,  soluble  in  alcohol,  and  in  vola- 
tile and  fixed  oils.     They  cannot,  like  volatile  oils,  be  dis- 
tilled with  the  aid  of  water.     When  subjected,  per  se,  to 
the  distillatory  process,  they  are  decomposed,  as  above 
mentioned,  into  carburetted  hydrogen,  carbon,  peculiar  re- 
sins, and  volatile  oils,  some  acids,  and  more  or  less  car- 
bon partly  in  the  state  of  lamp-black,  partly  in  union  with 
the  other  products,  whence  their  dark  or  black  colour. 

5136.  In  few  instances  do  resins  assume  a  crystalline 
form.     They  are  brittle  when  pure,  and  generally  translu- 
cent, rarely  colourless,  having,  commonly,  various  hues  of 
yellow  or  brown,  but  sometimes  green  or  red.     There  is  a 
great  resemblance  in  properties  between  resins  and  con- 
crete oils,  such  as  suet,  tallow,  spermaceti. 

5137.  Resins  are  distinguished  by  a  greater  hardness 
and  tenacity,  and  in  being  sticky  to  the  touch  instead  of 
being  greasy.     Hence  rosin  serves  to  create  the  necessary 
attrition  between  the  hair  of  the  bow  and  the  strings  of 
the  violin,  which  is  an  effect  the  opposite  of  that  for  which 
oil  is  used  in  machinery.     In  this,  as  well  as  in  other  re- 
spects, wax  approaches  the  resins  in  character  more  than 
any  other  concrete  fixed  oil.      But  this  adhesiveness  is 
much  increased  by  heat,  so  that  at  ordinary  temperatures 
copal,  amber,  and  many  other  resins,  are  not  sticky.     In 
consistency  resins  much  resemble  gums,  but  are  distin- 
guished from  them  by  insolubility  in  water,  and  solubility 
in  fixed  and  volatile  oils,  and  generally  in  alcohol  and 
ether. 

5138.  Some  resins  resemble  fixed  oils,  in  containing  two 
substances,  of  which  one  is  more  soluble,  the  other  less  so- 
luble in  alcohol.     This  characteristic  is,  in  some  instances, 
displayed  in  their  habitudes  with  some  essential  oils.     Ro- 
sin, for  instance,  is  said  to  be  only  partially  soluble  in 
naphtha. 

5139.  Resins,  also,  are  susceptible  of  saponification,  so 
far  as  to  combine  with  alkaline  and  other  bases  forming 
salts,  in  which  the  base,  being  imperfectly  neutralized,  pos- 
sesses the  detersive  power.     It  is  well  known  that  rosin 
is  a  constituent  of  common  brown  soap,  yet,  according  to 
Ure,  it  cannot  enter  into  it  advantageously  beyond  the 
proportion  of  a  third.     There  is  this  important  difference, 
however,  in  the  phenomena  of  the  reaction  of  fixed  oils 


OF  RESINS.  445 

with  bases,  and  that  of  resins,  that  there  is  no  base  to  be 
expelled  analogous  to  the  oxide  of  glyceryl. 

5140.  Concentrated  nitric  acid  and  resins  react,  in  some 
cases,  with  an  explosive  ignition.     According  to  Berzelius, 
they  dissolve  in  concentrated  sulphuric  acid,  when  cold, 
without  decomposition,  although  when  hot  reciprocal  de- 
composition ensues.     I  have  ascertained  that  sulphuric 
acid    forms,  either  with  oil  of  sassafras,  or   with   oil  of 
cloves,  resins,  by  which  it  is  coloured  to  a  miraculous  de- 
gree, since  a  six-millionth  part  suffices  to  create  a  rosy 
tinge.     A  similar  effect,  in  an  inferior  degree,  ensues  from 
the  presence  of  oil  of  cloves.     To  the  resins  thus  produced, 
I  have  given  the  names  of  sassarubrin  and  cinnarubrin. 
I  believe  in  any  case  it  will  be  found,  that  more  or  less 
resin  is  produced  by  the  reaction  of  concentrated  sulphuric 
acid  with  essential  oils.     In  fact,  such  oils,  to  a  certain 
extent,  act  as  bases  to  this  acid,  diminishing  the  sourness 
of  a  diluted  solution,  and  when  such  a  solution  is  saturated 
with  ammonia,  a  resin  formed  from  the  oil  separates. 

5141.  Resins  are  soluble  without  alteration,  either  in 
acetic  or  chlorohydric  acid.* 

5142.  Prof.  F.  W.  Johnson  has  proposed  to  represent 
all  resins  by  two  general  formulae,  either  of  which  contains 

*  It  appears  from  Unverderben's  laborious  investigations,  that  by  the  various  use 
of  cold  or  hot  alcohol  or  ether,  resins,  as  they  are  found  in  nature,  may  be  resolved 
into  various  substances,  differing  from  each  other  as  respects  readiness  to  combine 
with  bases;  so  that  he  has  classed  them  as  resins  strongly  electro-negative,  mode- 
rately electro-negative,  feebly  electro-negative,  and  indifferent.  This  author  founds 
this  diversity  of  designation,  on  their  greater  or  less  disposition  to  combine  with 
ammonia,  carbonate  of  soda,  or  caustic  alkaline  solutions. 

Agreeably  to  Johnson's  Report  to  the  British  Association,  for  1832,  Buchner  and 
Herberger  had  described  some  resins  as  having  weak  basic  properties.  Resins  ex- 
tracted from  jalap  and  euphorbium  had  each  been  found  a  compound  of  two  resins 
and  one  acid,  the  other  a  weak  base:  also  all  drastic  gum  resins  were  considered  by 
those  chemists  as  similarly  compounded. 

It  is  well  known  that  all  resins  are  electrics,  and  by  friction  become  negatively 
electrified. 

According  to  the  author  last  mentioned,  sandarach  is  a  mixture  of  three  resins; 
copal  of  five;  benzoin  of  three;  guiac  of  two;  and  lac  and  colophony  of  several. 

When  rosin  or  colophony  is  subjected  to  cold  alcohol,  of  the  density  of  867°,  one 
portion  dissolves,  called  alpha  resin  or  pinic  acid;  while  another  remains,  called  beta 
resin  or  sylvic  acid.  By  exposing  pinic  acid  to  distillation,  another  acid  is  generated 
called  colopholic.  Again,  the  solution  of  pinic  acid  may  be  decomposed  by  acetate 
of  copper,  of  which  the  oxide  precipitates  with  the  acid,  leaving  an  indifferent  resin 
in  solution. 

The  white  rosin,  from  the  pinus  maritina,  consists  of  an  acid,  crystallizable  resin, 
called  pimaric  acid.  Distilled  in  vacuo,  pimaric  acid  gives  rise  to  another,  called 
pyromaric  acid.  Boiled  with  nitric  acid,  pimaric  yields  azomaric  acid.  But  there  is 
no  end  to  the  variety  of  compounds  resulting  from  subjecting  resins  to  heat  and  va- 
rious solvents.  It  may  be  of  some  practical  importance  to  know,  that  resins  are  not 
homogeneous  substances,  and  that  even  the  rosin  of  different  trees  may  contain  dif- 
ferent acids. 


446 


ORGANIC  CHEMISTRY. 


forty  atoms  of  carbon,  while  one  holds  from  sixty  to  sixty- 
eight  atoms  of  hydrogen,  with  from  one  to  twenty  of  oxy- 
gen; the  other,  forty  to  fifty-four  of  hydrogen  with  from 
seven  to  fourteen  atoms  of  oxygen. 

5143.  He  infers,  that  the  resin  of  scammony,  C40  H33  O20, 
extracted  from  crude  scammony  by  alcohol,  contains  the 
largest  quantity  of  oxygen  of  any  resin  hitherto  analysed; 
and  that  the  resin  of  jalap,  obtained  by  evaporating  the  al- 
coholic extract,  and  subsequent  boiling  in  water,  of  which 
the  formula  is  C40  H34  O18,  is,  as  respects  the  quantity  of 
contained  oxygen,  surpassed  only  by  scammony. 

5144.  Agreeably  to  the  same  author,  there  is  a  striking 
relation  between  the  formulae  of  the  resins  of  ammoniac 
and  asafcetida,  the  former  being  C40  H25  O9,  the  latter,  C40 
H26  O10,  as  if  the  one  were  merely  a  hydrate  of  the  other. 

5145.  Berzelius  considers  our  knowledge  of  the  compo- 
sition of  resins  as  yet  too  imperfect  to  justify  us  in  placing 
much  confidence  in  these  suggestions  of  Johnson  as  to  the 
grouping  of  all  resins  under  two  formulae  as  above  men- 
tioned.    Report  for  1841,  171. 

5146.  The  following  list  of  the  more  important  resins  of 
commerce,  with  their  formulae,  is  taken  from  Kane's  Ele- 
ments, p.  969. 

Anime  Resin 
Elemi  Resin 
Fossil  Copal 
B.*  Mastic  Resin 
Antiar  Resin 
B.  Copal  Resin 
Birch  Resin 
A.  Mastic  Resin 
Copaiva  Resin 

A.  Elemi  Resin 

B.  Olibanum  Resin 

C.  Sandarach 
Ammoniac  Resin 
B.  Asafoetida 
Guiacum 
Bdellium  Resin 
A.  Sandarach 

Of  Wax. 

5147.  This  word  is  generally  used  to  designate  the  sub- 
stance of  which  bees  make  their  honeycomb;  more  accu- 


C40H33O 

B.  Sandarach 
A.  Euphorbium 

C40H32O 

Asphaltene 

C49H31O2 

A.  Olibanum 

C«H30Oa 

Labdanum 

C40H31O3 

Pasto  Resin 

C40H33O3 

Sagapenum 

C40H31O4 

Scammony 
Jalap  Resin 

C40H32O4 

Galbanum 
Dragon's  Blood 

O°H30O6 

Gamboge 

C40H24O9 

A.  Asafcetida 

C40H26O9 

Acaroid  Resin 

C45H23O10 

Opoponax 

B.  Benzoin  Resin 

V 

A.  Benzoin  Resin 

O°H3106 
C40H3208 

C48H3SO7 
C40H32O8 


C40H33O20 
C40H34O20 


C40H20O19 
C40H30O13 


C40H2209 


*  Where  a  native  resin  has  been  separated  into  two,  by  solvents,  the  letters  A  and 
B  are  used  to  distinguish  one  from  the  other. 


OF  WAX.  447 

rately  called  bees- wax.  Other  kinds  of  wax  are  found  to 
form  the  pollen  of  flowers,  the  varnish  on  the  upper  sur- 
faces of  the  leaves  of  certain  trees,  and  the  skins  of  certain 
stone  fruit ;  also  to  be  yielded  by  the  cabbage,  and  in  a 
large  proportion  by  the  berries  of  several  species  of  the 
myrtle,  myrica  angustifolia,  latifolia,  and  cerifera. 

5148.  Formerly  bees-wax  was  supposed  to  arise  from 
the  pollen  of  flowers  swallowed  and  excreted  by  bees;  but 
it  has  been  proven  that  the  wax  of  bees  is  secreted  by  an 
organ  situated  on  the  sides  of  the  medial  line  of  the  abdo- 
men of  the  insect.     On  raising  the  lower  segments  of  the 
abdomen  these  sacs  were  observed ;  also  the  scales,  or 
spangles  of  wax  arranged  in  pairs  upon  each  segment. 
Mr.  Huber  ascertained  that  bees,  while  prevented  from 
going  abroad  in  quest  of  food,  and  fed  solely  on  sugar, 
were  capable  of  generating  wax. 

5149.  These  conclusions  have  been  strengthened  by  the 
fact,  that  myrtle  wax  yields,  by  saponification,  stearic, 
margaric,  and  oleic  acids,  and  glycerine,  like  a  true  fat, 
while,  when  subjected  to  the  same  reagents,  bees-wax  is 
capable  only  of  a  partial  saponification,  yielding  in  lieu  of 
any  congener,  of  ethal,  or  of  the  sweet  principle  of  oils,  a 
substance  called  cerain,  which  differs  neither  in  composi- 
tion nor  properties  from  that  portion  of  wax  which  is  inso- 
luble in  boiling  alcohol. 

5150.  This  portion  has  been  called  myricine,  while  the 
portion  dissolved  in  the  hot  alcohol  is  called  cerine.     It  is 
cerine  only,  that  is  capable  even  of  the  partial  saponifica- 
tion to  which  allusion  has  been  made.     As  respects  this 
separation  into  cerine,  and  myricine,  by  boiling  alcohol, 
bees-wax  resembles  a  fat,  consisting  of  stearine  and  mar- 
garine, while  devoid  of  oleine;  but  in  its  chemical  constitu- 
tion and  habitudes,  with  bases,  it  resembles  the  resins. 
Wax  is  also  destitute  of  the  greasiness  or  slipperiness  of 
fat,  tending,  when  interposed  between  surfaces,  to  impede 
their  sliding,  rather  than  to  facilitate  it  like  an  oil.    Upon 
the  whole  I  consider  bees-wax  as  a  substance  intermediate 
between  a  concrete  fixed  oil  and  a  resin. 

5151.  The  yellow  wax  of  commerce  is  obtained  by  fu- 
sing, and  washing,  the  crude  wax  of  the  comb  with  boiling 
water.   Yellow  wax  is  converted  into  white  wax  by  causing 
it  to  form  thin  ribbons  by  flowing  while  melted  upon  a  re- 
volving wooden  cylinder,  half  immersed  in  water,  and  sub- 


448  ORGANIC  CHEMISTRY. 

sequently  exposing  these  ribbons  to  the  solar  light  and  the 
air,  as  in  the  old  process  for  bleaching  linen.  The  wax  of 
the  honeycomb,  before  being  supplied  with  honey,  is  white. 
5152.  Pure  white  wax  is  of  the  specific  gravity  960,  966. 
It  is  insipid  and  inodorous,  insoluble  in  water,  partially  so- 
luble in  boiling  alcohol,  and  perfectly  soluble  in  essential 
or  fixed  oils.  It  fuses  at  about  154°.  Its  general  uses  are 
too  well  known  to  need  description.  Not  being  much  act- 
ed on  by  acids,  it  is  used  to  defend  corks,  and  as  cement 
or  lute,  for  chemical  apparatus.* 

Of  Caoutchouc  or  Gum  Elastic,  and  Caoutchoucine. 

5153.  Caoutchouc  exudes,  in  the  state  of  an  emulsion,  from  incisions 
made  in  certain  trees,  and  congeals  in  the  form  of  the  mould  upon  which  it 
may  be  received.     Like  essential  oils,  devoid  of  oxygen,  it  consists  only  of 
carbon  and  hydrogen,  C8  H7.     As  respects  its  chemical  habitudes,  it  might 
be,  considered  as  a  resin,  were  it  not  for  its  wonderful  and  peculiar  elasti- 
city, and  the  mechanico-chemical  property  of  allowing  gases  to  get  through 
its  pores  with  a  celerity  not  corresponding  with  the  minuteness  of  their 
atomic  weights.     In  its  native  state,  instead  of  being  held  in  solution,  as  re- 
sins are  usually,  by  an  essential  oil,  it  is  merely  suspended  in  water,  as  but- 
ter and  caseine  are  in  milk.     Faraday  found  in  a  portion  of  caoutchouc 
milk  which  he  examined,  the  following  ingredients: — 

Brown  bitter  azotized  matter,  soluble  in  alcohol  and  water,  and 

precipitable  by  nitrate  of  lead, 

Vegetable  albumen,  .... 

Substance  soluble  in  water,  insoluble  in  alcohol, 
Water  holding  a  small  quantity  of  free  acid, 
Caoutchouc,  .... 

100.00 

5154.  Pure  caoutchouc,  carefully  prepared  from  the  native  emulsion,  is 
of  the  density  of  .925,  being  transparent  and  colourless,  and,  when  in  mass, 
yellowish  white. 

5155.  It  is  utterly  insoluble  in  water  or  alcohol,  but  soluble  in  pure  ether 
(oxide  of  ethyl),  and  likewise  generally  in  pure  essential  oils,  especially  oil 

*  Of  Cerosie. — Mr.  Avequin  has  examined  the  wax  which  covers  the  sugar  cane, 
and  the  lower  part  of  the  leaves  by  which  it  is  surrounded.  It  may  be  obtained  by 
scraping  the  surfaces  covered  with  it.  In  the  violet  variety  of  the  plant  in  question, 
this  wax  is  so  abundant,  that  it  Is  inferred  by  Mr.  Avequin  that  it  might  be  profitably 
collected  for  the  purpose  of  making  candles.  The  scrapings  are  digested  in  cold  al- 
cohol to  remove  impurities.  Afterwards  they  are  dissolved  in  boiling  alcohol.  This 
solvent  being  removed  by  distillation,  the  wax  is  isolated. 

This  wax  is  slightly  yellow,  hard,  brittle,  easily  reducible  to  powder  of  a  bright 
white,  fuses  at  176°,  and  burns  like  ordinary  wax  or  spermaceti.  It  is  less  soluble  in 
ether  than  alcohol.  From  boiling  solutions  in  either  solvent,  it  separates  in  pearly 
needle-shaped  crystals  by  refrigeration.  Mr.  Avequin  proposes  for  this  wax  the 
name  cerosie,  from  the  Greek  ceros,  wax.  The  formula  of  this  wax  is,  according  to 
analysis  by  Dumas,  C2Q  HW  O'. 


OF  CAOUTCHOUC.  449 

of  sassafras,  cajeput,  and  turpentine.  It  does  not,  however,  readily  liquefy, 
but,  absorbing  many  times  its  bulk  of  the  solvent,  may  be  liquefied  after- 
wards by  rubbing  through  a  sieve.  It  is,  perhaps,  even  more  soluble  in  the 
pyrogene  oils,  such  as  naphtha,  whether  native  or  as  obtained  from  coal, 
and  in  the  peculiarly  volatile  oil,  called  caoutchoucine,  which  it  yields  itself 
by  destructive  distillation,  and  repeated  subsequent  rectifications.  It  has 
been  mentioned,  that  this  oil  was  lighter  than  any  analogous  native  product. 
It  is,  in  fact,  lighter  and  more  volatile  than  common  ether,  its  density  being 
only  670,  and  for  its  boiling  point  90°.  From  none  of  the  volatile  oils,  not 
even  caoutchoucine,  have  I  recovered  caoutchouc,  without  more  or  less  de- 
terioration. This  may  be  presumed  to  arise  from  a  minute  quantity  of  re- 
sinous matter  formed  at  the  expense  of  the  solvent  which  remains  with  the 
caoutchouc.  I  have  found  a  great  diversity  in  the  solubility  of  caoutchouc. 
Neither  in  caoutchoucine,  nor  in  ether,  have  I  found  the  ordinary  bag  caout- 
chouc to  dissolve  readily.  It  softens  and  swells  up,  but  does  not  liquefy. 
But  a  large  lump  of  massive  caoutchouc,  sent  to  me  from  London  by  Mr. 
Enderby,  was  readily  liquefied  either  by  the  one  or  the  other  of  the  last 
mentioned  solvents,  and  by  the  ether  was  deposited  in  a  perfect  state.  I 
have  not  learned  the  source  of  the  more  soluble  caoutchouc  thus  alluded  to, 
nor  have  I  met  with  any  notice  respecting  this  difference  of  solubility. 
Caoutchouc  burns  with  an  excessively  fuliginous  flame  in  atmospheric  air, 
but  in  oxygen  gives  an  intense  light  by  the  oxidation  of  the  carbon  forming 
the  smoke  (645).  When  fused,  per  se,  it  is  converted  into  a  tarry  matter, 
which  does  not  indurate  by  drying.  This  tar  may  be  ignited  by  nitroso- 
nitric  acid. 

5156.  Dr.  Mitchell  ascertained  that  caoutchouc  bags,  after  soaking  in  a 
mixture  of  ether  and  alcohol  of  the  specific  gravity  of  from  750°  to  780°, 
or  the  usual  officinal  strength,  may  be  inflated  with  air,  and  the  material  of 
which  they  consist  consequently  extended  to  various  degrees  of  tenuity,  ac- 
cording to  the  peculiar  character  of  the  variety  subjected  to  trial.     Hence 
it  may  be  used  to  make  balloons,  gas  bags,  or  sheet  gum  elastic,  which  is 
very  useful  for  fillets,  with  which  to  make  air-tight  junctures  or  lutings. 
There  is  no  better  mode  of  joining  a  tube  to  the  tubulure  of  a  retort,  or  re- 
ceiver, than  by  tying  about  the  tubulure  the  body  of  a  small  caoutchouc 
bag,  while  the  tube  is  inserted  into  the  neck,  and  carefully  secured  by  a 
ligature.     Fused  caoutchouc  is  useful  in  some  cases  as  a  lute.     It  will  not, 
however,  resist  fuming  nitroso-nitric  acid. 

5157.  Dr.  Mitchell  has  made  some  very  interesting  observations  respect- 
ing the  power  of  gases  to  pass  through  thin  membranes  of  caoutchouc. 
By  some  inconceivable  process,  gases,  which  are  all  prone,  in  a  greater  or 
less  degree,  to  reciprocal  intermixture,  will  effect  this  result,  notwithstand- 
ing the  interposition  of  caoutchouc,  and  the  opponent  influence  of  great 
pressure. 

5158.  When  a  vessel  filled  with  atmospheric  air,  and  having  the  mouth 
closed  by  a  caoutchouc  membrane,  was  introduced  into  a  vessel  of  hydro- 
gen, this  gas  made  its  way  into  the  vessel,  until  the  membrane  burst  out- 
wards; but  when  the  vessel,  while  similarly  closed  by  the  membrane,  and 
replete  with  hydrogen,  was  exposed  to  common  air,  the  hydrogen  escaped 
until  the  membrane  burst  inwards.     A  tube,  with  a  trumpet-shaped  mouth, 
being  bent  so  as  to  form  a  syphon,  and  the  larger  orifice  closed  by  the  mem- 
brane while  full  of  atmospheric  air,  a  suitable  quantity  of  mercury  was 
poured  into  the  syphon,  until  it  stood  in  both  legs  at  the  same  height.     Un- 
der these  circumstances,  when  the  membrane  was  brought  into  contact  sue- 


450  ORGANIC  CHEMISTRY. 

cessively  with  different  gases,  they  were  found  to  enter  with  various  degrees 
of  celerity,  as  will  appear  from  the  following  statement : — 

H.        M. 

Ammoniacal  gas        ----01 

Sulphydric  acid  0  2£ 

Cyanogen  0  3^ 

Carbonic  acid  -                             0  5£ 

Protoxide  of  nitrogen  -         -         -         0  6£ 

Arseniuretted  hydrogen  -                             0  27^ 

Olefiant  gas      -  0  28 

Hydrogen  0  37£ 

Oxygen  1  13 

Carbonic  oxide  -         -         2  40 

Nitrogen  3  15 

5159.  The  gases  continued  in  some  instances  to  enter  until  the  mercury 
in  the  longer  leg  rose  to  the  height  of  sixty  inches. 

5160.  It  is  quite  surprising  that  the  atoms  of  ammonia  should  pass 
through  the  membrane  with  greater  celerity  than  those  of  hydrogen,  when 
each  of  the  former  consists  of  three  of  the  last  mentioned  gas,  united  with 
one  atom  of  nitrogen.     Also  that  two  atoms  of  oxygen,  while  associated 
with  an  atom  of  carbon,  should  permeate  the  membrane  more  speedily  than 
an  isolated  atom  of  oxygen. 

5161.  It  also  appears  from  experiments  made  by  Dr.  Mitchell,  and  re- 
peated by  myself,  that  caoutchouc  is  probably  more  highly  susceptible  of 
electric  excitement,  than  any  other  organized  body ;  and  probably  is  at  least 
equal  in  excitability  to  any  inorganic  substance. 

Of  Balsams. 

5162.  The  word  balsam  has  been  used  to  designate  na- 
tive solutions  of  resinous  matter  in  essential  oils,  which, 
like  the  turpentine  of  commerce,  exude  spontaneously  from 
trees  or  shrubs. 

5163.  Among  these,  however,  there  are  some  distin- 
guished by  the  presence  of  benzoic  or  cinnamic  acid,  or 
both.     It  is  to  the  balsam  of  Peru  and  Tolu  that  this  re- 
mark applies  particularly  (3060).     Styrax  has  also  been 
alleged  to  contain  a  minute  proportion  of  benzoic  acid, 
but  is  not  included  among  balsams  by  Soubieran,  and  by 
this  author  the  corresponding  French  word  baume  is  em- 
ployed to  designate  artificial  compounds  of  resins  with  an 
acid  and  volatile  oil. 

5164.  According  to  Fremy,  balsam  of  Peru  consists  of 
resinous  matter,  of  cinnamic  acid,  a  liquid  essential  oil, 
called  cinnameine,  and  a  crystallizable  oil  supposed  to  be 
a  hydrate  of  cinnamyle  (3058),  called  metacinnameine. 

5165.  Balsam  of  Tolu  consists  of  resin,  cinnameine, 
cinnamic  acid,  and,  perhaps,  metacinnameine. 


OF  GUM-RESINS.  451 

5166.  Balsam  of  copaiva,  or  copaiva  balsam,  consists 
of  a  volatile  oil,  and  two  resins  without  any  acid. 

5167.  But  agreeably  to  the  investigations  of  Deville, 
benzoic  acid  also  exists  in  the  two  first  mentioned  balsams, 
and  when  the  balsam  of  Tolu  is  distilled,  per  se  over  a 
naked  fire,  a  volatile  oil,  and  likewise  benzoic  ether,  are 
obtained.     It  is  suggested  that  the  resin  of  the  balsam  is 
an  oxide  of  this  ether. 

5168.  It  appears  that,  by  reaction  with  caustic  potash, 
cinnameine  is  resolved  into  cinnamic  and  benzoic  acid 
in  union  with  the  alkali :  an  oily  substance,  little  soluble 
in  water,  called  peruvine,  being  simultaneously  evolved. 
There  is  some  analogy  between  this  process,  with  its  re- 
sults, and  those  of  saponification. 

5169.  By  some  authors  the  word  balsam  is  restricted 
to  resiniferous  liquids  containing  benzoic  acid.     It  might 
be  more  reasonable  to  consider  an  acid  of  some  kind  as 
requisite,  yet  it  is  evident  that  ordinary  acceptation  does 
not  justify  the  idea  that  the  presence  of  an  acid  is  neces- 
sary. 

Of  Gum-resins. 

5170.  This  name  is  applied  to  a  class  of  vegetable  sub- 
stances, which  consist  of  a  mixture  of  resin,  gum,  essential 
oil,  and  extractive  matter.     Opium,  aloes,  ammoniac,  asa- 

fcBtida,  eupJiorbium,  galbanum,  gamboge,  myrrh,  and  scam- 
mony  come  under  this  head. 

5171.  As  the  resin  and  essential  oil  require  alcohol,  the 
gum  and  extractive  matter  water,  for  solution,  proof  spirit 
is  the  best  solvent  of  the  gum-resins. 

Of  Opium. 

5172.  This  complex  substance  contains  the  following 
proximate  principles ; — 

1.  Morphia,  in  the  state  of  neutral  sulphate,  and  super- 
meconate. 

2.  Paramorphia. 

3.  Pseudomorphia. 

4.  Codeia,  in  the  state  of  supermeconate. 

5.  Narcotina. 

6.  Narceia. 

7.  Meconin. 

8.  Meconic  acid,  partly  combined  with  bases. 

58 


452  ORGANIC  CHEMISTRY. 

9.  Ulmin. 

10.  A  peculiar  resin. 

11.  A  fatty  oil. 

12.  Caoutchouc. 

13.  Gum. 

14.  Bassorin. 

15.  Lignin. 

16.  The  sulphate  of  potash,  lime,  and  magnesia. 

5173.  Of  these  substances,  morphia,  par  amor pliia,  pseudo- 
morphia,  codeia,  narcotina  and  narceia  are  ranked  as  vege- 
table alkalies,  all  having  the  power  of  neutralizing  acids. 
Meconin  is  an  indifferent  or  neutral  subtance,  which  was 
announced  to  exist  in  opium  in  1832,  by  M.  Couerbe,  but 
which  is  found  to  be  identical  with  the  crystalliz able  princi- 
ple of  M.  Dublanc,  jun.,  discovered  several  years  before. 
Paramorphia,  pseudomorphia,  narceia,  and  meconin,  exist  in 
opium  in  very  small  amount.     For  a  method  of  detecting 
opium,  see  meconic  acid  (5265). 

Of  Bitumen,  Petroleum,  Naphtha,  Amber,  and  Mineral 

Coal. 

5174.  There  is  in  nature  a  gradation  of  substances, 
apparently  arising  from  the  wreck  of  a  former  world,  from 
naphtha,  which  is  highly  volatile,  to  anthracite,  which  is 
extremely  insusceptible  of  the  aeriform   state.     Possibly 
the  diamond  may  be  considered  as  terminating  the  series; 
as  it  has  been  suggested  to  result  from  the  decomposition 
of  vegetable  matter. 

5175.  Bitumen,  in  a  concrete  state,  is  exemplified  by  asphaltum.     The 
coal  called  bituminous,  owes  to  the  presence  of  bitumen  its  capability  of 
caking,  and  yielding  carburetted  hydrogen  when  ignited.    Bitumen  is  found 
also  in  a  tarry  state,  or  more  or  less  liquid,  according  to  the  quantity  of 
petroleum  with  which  it  may  be  united.     Caking  coal  may  be  considered 
as  a  compound  of  carbon  with  bitumen,  and  a  minute  portion  of  silex  and 
iron,  and  sulphur:  anthracite,  as  consisting  of  the  same  ingredients,  substi- 
tuting water  for  bitumen,  though  in  a  lesser  proportion. 

5176.  Petroleum,  or  naphtha,  is  the  name  given  to  an  inflammable  liquid 
which  rises  out  of  the  earth  like  spring  water,  so  that  some  wells  cannot  be 
freed  from  it.    The  name  of  naphtha  is  more  properly  given  to  a  very  vola- 
tile oil  which  may  be  obtained  from  petroleum  by  cautious  distillation,  prefer- 
ably with  water.    Besides  more  or  less  bitumen,  by  which  it  is  discoloured  to 
a  greater  or  less  degree;  agreeably  to  the  researches  of  Pellelier  and  Walter, 
petroleum  comprises  three  volatile  oils,  and  a  species  of  paraffin.     The 
names,  boiling  points,  and  formulas  of  the  oils,  are  as  follows: — naphthol, 
C3*  H32,  boils  at  384° ;  naphthene,  C10  H16,  boils  at  239° ;  naphtha,  C14  H13, 
boils  between  185°  and  194°. 


OF  ACIDS.  453 

5177.  Naphtha  proper. — The  last  mentioned  oil  may  be  considered  as 
the  true  naphtha,  being  the  liquid  employed  for  the  preservation  of  the  me- 
tals of  the  alkalies.     It  much  resembles  oil  of  turpentine  in  properties  and 
composition.    Potassium,  of  which  the  specific  gravity  is  .865,  sinks  readily 
in  naphtha. 

5178.  During  the  destructive  distillation  of  bituminous  coal,  a  bituminous 
liquid,  called  coal  tar,  condenses,  from  which  an  artificial  naphtha  may  be 
extricated,  which  is  used  as  a  solvent  of  caoutchouc. 

5179.  Seneca  Oil,  American  Oil. — Under  these  names  two  liquids  are 
now  to  be  met  with  in  commerce.    The  former  is  obtained  from  the  vicinity 
of  the  lake  after  which  it  is  named ;  the  latter  from  a  well  in  Kentucky, 
which  was  sunk  for  the  purpose  of  obtaining  spring  water.     Either  yield, 
by  distillation  with  water,  more  or  less  naphtha,  arid  contain  heavier  oils 
requiring  a  higher  heat  to  bring  them  over  by  distillation. 

5180.  Amber  is  a  singular  fossil,  which  is  supposed  to  owe  its  origin  to 
vegetable  matter.    It  is  distinguished  by  burning  with  a  peculiar  odour,  and 
yielding,  when  subjected  to  distillation,  succinic  acid,  and  a  peculiar  essen- 
tial oil,  called  oil  of  amber,  which  resembles  crude  naphtha  in  smell  and 
other  properties.     The  acid  sublimes  into  the  neck  of  the  retort  in  crystals. 
Amber  is  insoluble  both  in  water  and  alcohol.     Dr.  Kane  suggests  that  it 
may  be  the  turpentine  of  an  extinct  species  of  tree,  belonging  to  a  former 
geological  epoch.     It  would  seem  rather  to  be  a  variety  of  copal,  which  it 
so  much  resembles  in  appearance  and  properties,  as  that  the  one  may  be 
mistaken  for  the  other,  on  superficial  examination. 


OF  ACIDS. 

Of  Acids  relatively  to  the  Proportions  of  Base  required  for 
their  Saturation. 

5181.  It  has  long  been  known,  that  certain  acids,  such 
for  instance  as  nitric,  or  chloric  acid,  cannot  be  isolated  so 
as  neither  to  be  in  unison  with  water,  nor  with  any  other 
oxide  acting  as  a  base.  Until  of  late,  however,  it  does  not 
seem  to  have  been  perceived,  that  the  water  in  such  acids 
must  act  as  a  base.  Now  it  is  held,  that  wherever  water, 
unless  replaced  by  another  oxide,  cannot  be  expelled  from 
an  acid  without  a  decomposition  of  the  acid,  or  a  destruc- 
tion of  its  properties,  such  water,  while  combined  with 
the  acid,  must  be  considered  as  acting  as  a  base.  More- 
over, as  when  one  atom  of  water,  or  other  oxide,  is  found 
indispensable  to  the  existence  of  an  acid,  that  one  atom 
has  been  considered  as  performing  a  basic  part,  so,  con- 
sistently, when  two  or  three  atoms  of  water  or  other  oxide 
are  ascertained  to  be  no  less  necessary,  the  two  atoms,  or 
three  atoms  of  water  or  other  oxide  thus  required,  are  con- 
sidered as  acting  as  bases.  Experience  has  shown  that  in 
this  way,  some  acids  require  one,  others  two,  and  others 


454  ORGANIC  CHEMISTRY. 

three  atoms  of  base,  and  are  called  accordingly  monobasic, 
bibasic,  or  tribasic  acids. 

5182.  But.  it  may  be  inquired,  how  is  this  diversity  in 
the  acids  ascertained?     The  answer  is,  by  ascertaining  the 
loss  of  weight  which  they  sustain,  on  combining  with  a 
base  to  saturation.      Of  course,  the  weight  of  the  salt 
formed  with  a  dry  base,  should  be  the  aggregate  weight  of 
that  base  and  the  anhydrous  acid.     This  may  be  found  on 
desiccating  the  resulting  salt.     The  difference  between  the 
weight  of  this  Saline  aggregate,  and  that  of  the  sum  of  the 
weights  of  the  hydrated  acid  and  dry  base,  must  be  due  to 
the  escape  of  basic  water. 

5183.  Although  when  water,  which  can  be  replaced  by 
another  base,  is  essential  to  the  existence  of  an  acid,  it 
follows  that  it  must  be  considered  as  basic ;  the  student 
ought  not  to  infer  that  it  cannot  act  as  a  base  to  acids 
which  can  exist  without  it.     Both  sulphuric  and  phospho- 
ric acid  unite  with  water  as  a  base,  although  capable 
of  existing  in  the  anhydrous  state.     This  preliminary  ex- 
planation having  been  given,  it  is  hoped  that  the  stu- 
dent will  be  prepared  to  understand  the  following  state- 
ment, respecting  the  three  classes  of  acids  above  men- 
tioned. 

5184.  Acids,  as  respects  the  quantity  of  base  with  which 
they  are  capable  of  combining,  may  be  divided  into  three 
classes.     Those  requiring  one  equivalent  of  base,  called 
monobasic;  those  requiring  two  equivalents,  called  bibasic; 
those  requiring  three  equivalents,   called  tribasic    acids. 
Water  acts  as  a  base  in  combining  with  any  acid  of  either 
class,  and  is  subject  to  the  same  laws  as  other  bases. 

5185.  The  compounds,  hitherto  called  hydrated  acids, 
are  in  combination  with  one,  two,  or  three  atoms  of  basic 
water,  accordingly  as  they  belong  to  the  monobasic,  the 
bibasic  or  tribasic  class. 

5186.  When  the  hydrate  of  an  acid  of  either  kind  is  pre- 
sented to  a  base,  capable  of  displacing  water,  for  every 
atom  of  the  new  base  which  unites  with  the  acid,  an  atom 
of  water  must  be  expelled.     As  the  single  salts  of  mono- 
basic acids  can  have  only  one  equivalent  of  base,  so  in 
them  there  can  only  be  one  kind  of  base ;  but  in  bibasic 
acid  salts  the  equivalents  may  be  of  one  kind  only,  or  of 
two  kinds ;  and  in  tribasic  acid  salts,  of  one  kind,  or  of 


OF  ACIDS.  455 

two,  or  of  three  kinds.  In  either  case,  water,  acting  as  a 
base,  is  liable  to  be  present  in  the  same  proportions  as  any 
other  base,  and  may  replace  or  be  replaced  by  other  bases. 
All  that  has  been  said  of  water,  is  also  true  in  many  cases 
of  oxide  of  ammonium. 

5187.  Different  bases,  salified  by  the  same  monobasic 
acid,  may  combine  to  form  double  salts.     Of  course,  salts 
having  water  for  their  base  are  not  excepted ;  but  double 
salts  thus  formed  with  an  equivalent  of  basic  water,  on  ac- 
count of  their  sourness  or  reaction  with  litmus,  have  been 
called  acid  salts.     When  in  such  salts  the  water  is  re- 
placed by  another  base,  two  neutral  salts  result,  which 
may  be  separated  by  crystallization,  provided  they  differ 
in  solubility,  and  crystallize  separately,  in  forms  sufficient- 
ly different  to  be  distinguished. 

5188.  When  monobasic  acids  are  united  to  more  than 
one  equivalent  of  base,  not  being  neutral,  as  bibasic  or  tri- 
basic  acids  are,  with  the  same  number  of  basic  equivalents, 
they  are  called  basic  salts ;  which  conveys  the  idea  of  a 
salt  consisting  of  an  acid  united  to  one  or  more  atoms  of 
base  in  excess.     Yet  when  the  atoms  thus  situated,  are 
presented  to  another  atom  of  the  same  monobasic  acid,  in 
the  state  of  hydrate,  they  can  displace  no  more  than  one 
atom  of  basic  water;  for  this  obvious  reason,  that  there 
can  be  no  more  than  one  atom  of  basic  water  in  union 
with  such  an  acid. 

5189.  Salts  of  bibasic  acids,  when  one  of  their  atoms  of 
base  is  water,  are,  from  their  sourness,  called  acid  salts ; 
yet,  substituting  another  base  for  water,  does  not  produce 
a  double  salt.     For  this,  two  atoms  of  acid  and  four  atoms 
of  base  would  be  requisite. 

5190.  Acids  produced  by  dry  distillation,  are  called  py- 
rogene  acids.     Such  acids  are  rarely  created  by  subjecting 
monobasic   acids  to   that   process;    but  pyrogene  acids, 
when  thu^created,  are  always  monobasic. 

5191.  Under  like  circumstances,  bibasic  acids  give  birth 
often  to  two  new  monobasic  acids,  as  in  the  instance  of 
gallic  acid. 

5192.  By  the  same  process,  tribasic  acid  may  give  rise 
to  three  equivalents  of  a  monobasic  acid,  as  in  the  case  of 
cyanuric  acid;  or  they  may  be  resolved  into  two  monoba- 
sic acids,  or  a  bibasic  and  a  monobasic  acid,  as  may  be 
seen  in  the  case  of  meconic  acid. 


456  ORGANIC  CHEMISTRY. 

5193.  In  the  following  table,  taken  from  Gregory's  Lie- 
big,  the  anhydrous  acid  is  represented  by  R,  the  metallic 
oxybase  by  MO,  and  water  by  the  usual  symbol  HO. 

Formula  for  Monobasic  Salts. 

R  +  HO,  hydrate  of  acid. 

R-j-MO,  neutral  salt. 
(R  +  MO)+MO,  basic  salt. 
(2R+2MO+MO,       do. 
(R+MO)+2MO,     do. 

R  \  "*"  >    mO    \  double  salt  with  two  bases. 
8R  \  +  \    mo'  \  double  salt  with  two  bases' 


2R  >         2HO          .  ,     ,. 
MO      acidsaU' 


> 

,  $ 


General  formulae  for  the  salts  of  the  bibasic  acids. 
R     -f     2  HO,  hydrate  of  acid. 

R  +  \  ™  J  acid  salt. 
R  +  2  MO,  neutral  salt. 
R  -f  \  n  i  neutral  salt  with  two  bases. 

General  formulae  for  the  salts  of  the  tribasic  acids. 
R     -f     3HO,  hydrate  of  the  acid. 

f  OTJQ      i 

R     -f  J    ,-^    >  salt  with  one  atom  of  a  fixed  base. 

R     -f-  5  9T\1O    i  sa^  w^tb  two  atoms  °f  a  fixe(^  base. 
R     +     3MO,  tribasic  salt. 

HO    ) 
R     -f  <    MO    >  salt  with  two  different  fixed  bases. 

mO,  ^ 


Of  Acetic  Acid. 

5194.  Acetic  acid  is  monobasic,  being  a  hydrated  triox- 
ide  of  acetyl  (3093),  as  may  be  seen  from  its  formula, 
C4  H3  O3+HO. 

5195.  As  the  cause  of  the  sourness  in  fermented  liquors, 
and  various  products  of  vegetation,  this  acid,  having  been 


OF  ACETIC  ACID.  457 

the  first  to  attract  human  observation,  has  given  a  name 
to  the  whole  class  of  acids;  though  at  this  time  many  of 
the  compounds  recognised  as  acids,  are  devoid  of  the  attri- 
bute on  which  the  general  name  is  founded.  Acetic  acid 
is  the  only  valuable  ingredient  in  vinegar,  causing  the  sour- 
ness indicated  by  its  name,  which  differs  but  little  from 
vin  aigre,  the  words  expressive  of  sour  wine  in  French. 

5196.  This  acid  occurs  in  nature  in  many  products  of 
the  vegetable  and  animal  organization:  as  for  instance;  in 
the  black  elder  (sumbucus  niger);  the  pleurix  dactilifera, 
and  rhus  tiphinus;  in  sweat,  urine,  milk,  and  the  fluids  of 
the  stomach. 

5197.  It  had  long  been  observed  that  the  fermented  li- 
quors containing  the  most  spirit  made  the  strongest  vine- 
gars.    Although  pure  alcohol  is  not  liable  to  be  acidified 
per  se,  when  diluted  with  water  holding  fermentable  sub- 
stances, it  is  readily  converted  into  vinegar.     For  this 
purpose  each  atom  requires  four  of  oxygen.     Two  atoms 
of  this  element  are  requisite  to  remove  two  of  hydrogen, 
by  which  ethyl  (3069),  the  radical  of  the  alcohol,  is  changed 
into  acetyl  (3093),  the  radical  of  acetic  acid.    At  the  same 
time,  two  atoms  of  oxygen  are  required  to  be  added  to  the 
one  atom  previously  in  union  with  the  ethyl,  to  make  the 
three  required  for  acetic  acid,  which  is  a  trioxide  of  acetyl. 
The  formula  of  alcohol  is  C4  H5O+HO.     If  to  this  we  add 
four  atoms  of  oxygen,  we  have  C4  H5  O5+HO,  which  gives 
the  formula  of  hydrated  acetic  acid  =  C4  H3  O3  HO+2HO 
in  excess.*     See  paragraph  3094  and  note. 

5198.  I  shall  defer  the  exposition  of  the  phenomena, 
causes,  and  circumstances,  on  which  the  conversion  of  vi- 
nous liquids  into  vinegar  is  dependent,  until  I  treat  of  fer- 
mentation.    Practically,  every  body  has  a  general  idea  of 
the  mode  in  which  wine,  cider,  or  beer,  vinegar,  is  obtained. 

5199.  Ajcetic  acid  is  also  a  product  of  the  destructive 
distillation*of  wood.     In  that  case  it  forms  what  has  been 


*  Liebig  alleges  that  a  strong  and  agreeable  vinegar  may  be  made  by  exposing  to 
the  air  for  some  weeks  in  a  warm  situation,  the  following  mixture; — 100  parts 
water,  13  brandy,  4  parts  honey,  and  1  crude  tartar.  Of  course,  one  part  cream  of 
tartar  might  be  substituted  for  the  crude  tartar. 

The  acetification  of  mixtures  of  vegetable  juices  with  spirit,  has  been  very  much 
expedited,  of  late  years,  by  a  high  temperature,  and  allowing  the  liquor  to  drop  from 
a  tube  through  holes  like  those  of  a  colander,  on  beach  wood  shavings.  Respecting 
this,  and  other  processes  for  the  generation  of  acetic  acid,  much  information  will  be 
found  in  Ure's  Dictionary  of  Arts  and  Manufactures;  also  in  Liebig's  Traite  de 
Chymie  Organique,  386. 


458  ORGANIC  CHEMISTRY. 

called  pyroligneous  acid,  which  contains  various  other  sub- 
stances. From  these  the  acid  is  extricated  by  combining 
it  with  a  base,  and  subsequent  distillatory  decomposition 
of  the  resulting  salt  by  sulphuric  acid,  the  impure  acetate 
having  been  first  cautiously  fused  to  get  rid  of  impurities. 

5200.  The  acetic  acid,  thus  obtained,  is  much  diluted  with 
water,  from  which  it  may  be  freed  by  digestion  with  anhy- 
drous sulphate  of  soda,  and  subsequent  distillation.    In  this 
way,  according  to  Liebig,  a  sufficient  degree  of  concentra- 
tion may  be  attained  to  render  the  acid  crystallizable.    As 
in  the  case  of  other  organic,  acids,  that  in  question  cannot 
exist  excepting  in  combination  with  basic  water,  or  some 
other  base. 

5201.  The  distillation  of  dry  acetate  of  copper,  has  been 
long  made  the  means  of  evolving  the  contained  acid,  in  a 
concentrated  state.     Resort  has  also  been  had  to  the  de- 
composition of  the  dry  acetate  of  soda,  or  lead,  with  equi- 
valent portions  of  concentrated  sulphuric  acid.    1.  Accord- 
ing to  Liebig,  the  proportions  should  be,  3  acetate  of  soda, 
with  9.7  acid :  or,  3  acetate  of  lead,  with  8  acid. 

5202.  Pure  hydrated  acetic  acid  crystallizes  in  shining, 
transparent  lamellar,  or  tabular,  crystals.    At  the  tempera- 
ture of  63°  nearly,  these  crystals  fuse  into  a  limpid  liquid, 
of  the  density  of  1.063;  of  which  the  pungent  and  distin- 
guishing smell  and  taste  may  be  inferred,  from  the  inferior 
effect  of  strong  vinegar.     In  its  concentrated  form,  as  it 
is  capable  of  blistering  the  skin,  its  action  upon  the  tongue 
must  be  insupportable.     Like  other  liquids  greedy  of  wa- 
ter, it  produces  fumes  on  contact  with  the  aqueous  vapour 
of  the  atmosphere.     It  boils  at  142°,  and  unites  in  all  pro- 
portions with  water,  alcohol,  ether,  many  essential  oils, 
camphor,  and  some  resins.     When  in  the  state  of  vapour, 
it  is  capable  of  burning  with  a  blue  flame,  and  being  re- 
solved into  water  and  carbonic  acid. 

5203.  It  has  been  mentioned,  that,  when  liquid,  crystal- 
lizable acetic  acid  is  denser  than  water.     To  a  certain  ex- 
tent, by  admixture  with  this  liquid,  a  condensation  ensues; 
but  a  further  addition  of  water  causes  the  opposite  change. 
Equal  parts  by  weight  have  the  same  density  as  the  pure 
hydrate.     The  highest  density  attainable  is  107,  indicating 
the  presence  of  three  atoms  of  water,  and  one  of  anhydrous 
acid;  or  by  weight,  772  acid,  and  228  water. 


OF  ACETIC  ACID.  459 

5204.  Allusion  has  been  made  to  the  process  by  which 
platinum  black  causes  the  acetification  of  alcohol*  (1607). 

5205.  Of  Pyroligneous  Acid.     The  process   by  which 
charcoal   is   obtained   by   the   destructive   distillation   of 
wood,  has  been  mentioned  as  one  by  which  acetic  acid 
is  generated.    Thus  produced,  it  is  generally  known  as  py- 
roligneous  acid,  being  very  much  disguised  by  impurities. 
In  fact,  pyroligneous  acid  so  called,  contains  beside  the 
acetic  acid,  paraffine,  eupione,  kreosote,  and  the  pyrogene, 
resinous  matter,  called  pyretene  by  Berzelius. 

5206.  When  the  process  is  performed  with  a  suitable 
apparatus,  this  acid  is  collected.     Pyroligneous  acid  may 
be  considered  as  the  matter  of  wood  smoke  in  the  liquid 
form;  and  when  applied  in  this  state  to  salted  meat,  is  at 
least  as  efficacious  as  when  employed  as  smoke  in  the 
usual  way.     The  process  of  the  smoke-house  is  less  sus- 
ceptible of  precision,  and  is  liable  to  produce  an  injurious 
rise  of  temperature. 

5207.  Of  the  Acetates. — These  salts  are  soluble,  with 
very  few  exceptions.     Only  two  are  cited  as  insoluble  by 
Liebig;    those  of  molybdenum  and  tungsten.     The  ace- 
tates of  silver  and  of  the  protoxide  of  mercury,  are  soluble 
only  to  a  very  small  extent.    All  the  acetates  smell  of  ace- 
tic acid,  on  the  affusion  of  sulphuric  acid.     Those  formed 
with  oxides  of  the  metals  proper,  yield  their  acid  on  the 
application  of  heat,  with  a  partial  decomposition.     When 
the  base  is  a  fixed  alkali  or  alkaline  earth,  they  are  re- 
solved into  carbonates  and  acetone  (3098). 

5208.  When  in  diluted  aqueous  solution,  especially  when 
the  base  is  in  excess,  any  alkaline  acetate  undergoes  a 
partial  resolution  into  a  carbonate. 

5209.  Of  course,  any  of  the  acetates  may  be  formed  by 
the  saturation  of  the  acid  with  the  proper  base.     In  some 
cases,  they  may  be  obtained  advantageously  by  double  de- 

*  Dr.  Ure  alleges,  that  by  means  of  twenty  to  thirty  pounds  of  platinum  powder, 
which  does  not  waste,  \ve  may  transform,  daily,  three  hundred  pounds  of  bad  spirits 
into  the  finest  vinegar. 

For  this  purpose,  platinum  black  may  be  made,  by  fusing  platina  ore  with  twice 
its  weight  of  zinc;  pulverizing  the  resulting  alloy,  and  subjecting  it  successively  to 
diluted  sulphuric  and  diluted  nitric  acid,  the  latter  with  heat.  The  zinc  being  dis- 
solved or  oxidized,  the  residual  powder,  after  washing  with  a  solution  of  potash  and 
water,  is  fit  for  the  purpose  in  question. 

The  process  has  been  conducted  in  a  wooden  box  having  a  capacity  of  twelve  cu- 
bic feet. 

59 


460  ORGANIC  CHEMISTRY. 

composition,  as  illustrated  in  the  case  of  sulphate  of  zinc, 
and  acetate  of  lead,  which  when  added  together  in  a  state 
of  solution,  form  sulphate  of  lead  and  acetate  of  zinc. 
Formerly,  the  acetate  of  potash  was  known  as  foliated 
earth  of  tartar,  acetate  of  ammonia  as  spirit  of  minde- 
rerus. 

5210.  Of  Acetate  of  Ammonia,  or  Spirit  of  Mindererus. 
This  salt  may  be  obtained  by  distilling  sal  ammoniac  with 
acetate  of  soda,  when,  after  the  escape  of  some  ammonia, 
the  acetate  comes  over  liquefied,  and  crystallizes  in  trans- 
parent, colourless  needles. 

5211.  This  acetate  has  an  acid  reaction,  is  deliquescent, 
and  soluble  in  all  proportions  in  water  and  alcohol.     Of 
the  acetates  of  lead  some  mention  has  already  been  made. 
(1740.) 

5212.  Sugar  of  lead,  according  to  Liebig,  contains  an 
equal  number  of  atoms  of  acid  and  base.     Besides  this, 
there  is  sesguibasic  acetate,  consisting  of  two  atoms  of  acid, 
with  three  atoms  of  base. 

5213.  Tribasic  acetate,  consisting  of  one  atom  of  acid, 
with  three  atoms  of  base. 

5214.  Sexbasic  acetate,  holding  one  atom  of  acid  to  six 
atoms  of  base.     Sugar  of  lead  is,  of  course,  the  neutral 
acetate. 

Of  Lactic  Acid. 

5215.  This  acid  is  that  which  exists  in  sour  milk,  whence 
its  name  from  lac,  the  latin  for  milk.     It  has  lately  been 
shown  to  be  generally  the  product  of  a  peculiar  fermenta- 
tion, called  viscous,  to  which  the  juices  of  plants,  contain- 
ing albumen,  are  spontaneously  liable,  when  yeast  is  not 
added,  at  a  temperature  between  86°  and  104°.     This  fer- 
mentation differs  from  the  vinous,  in  being  accompanied 
by  the  evolution  of  inflammable  gases,  as  well  as  carbonic 
acid,  and  in  not  being  productive  of  alcohol,  but  of  lactic 
acid  and  manna  sugar,  or  mannite  (4074).     It  is  obtained 
from  sour  milk  by  saturation  with  soda,  and  decomposing 
the  resulting  lactate  by  sulphuric  acid.    By  a  previous  ad- 
dition of  lactin,  in  the  ratio  of  eight  ounces  to  eight  pints 
of  the  milk,  the  quantity  of  acid  produced  may  be  advan- 
tageously increased. 

5216.  Lactic  acid  is  monobasic,  and  as  it  exists  in  the 
anhydrous  salt  which  it  forms  with  zinc,  consists  of  C6H5O5. 


OF  CITRIC  OR  MALIC  ACID.  461 

Its  composition  is  remarkable,  since,  as  the  hydrogen 
and  oxygen  which  it  contains  exist  in  the  proportion  for 
forming  water,  it  might  be  represented  as  a  hydrate  of 
carbon;  a  composition  which  usually  belongs  to  bodies, 
which,  as  it  respects  basic  and  acid  properties,  act  indif- 
ferently. When  in  its  most  concentrated  form,  it  appears 
as  a  sour  syrup,  incapable  of  crystallization.  On  being 
heated  to  482°,  it  is  decomposed,  yielding,  among  other 
products,  a  large  amount  of  a  crystallized  acid  sublimate. 
As  this  consists  of  C6  H4  O4,  it  was  for  some  time  treated 
as  anhydrous  lactic  acid;  but  as  the  anhydrous  lactate  of 
zinc  is  said  to  contain  H5  O5,  this  sublimate  must  be  re- 
garded as  a  distinct  acid.  By  boiling  in  water,  the  new 
acid  combines  with  an  atom  of  oxygen  and  an  atom  of  hy- 
drogen, and  is  consequently  reconverted  into  lactic  acid. 

Of  Citric  and  Malic  Acid. 

5217.  The  name  of  citric  acid  indicates  its  origin.*     It 
exists  in  the  lime  and  lemon,  in  union  with  mucilage  and 
malic  acid.     Its  combination  with  mucilage  is  so  intimate 
as  to  render  it  impossible  to  separate  the  acid  without 
first  uniting  it  with  some  other  matter.     Alcohol  combines 
with  the  acid,  and  precipitates  the  mucilage.     Yet,  the  al- 
coholic solution,  thus  obtained,  does  not  yield  crystals, 
even  after  evaporation,  re-solution  in  water,  and  evapora- 
ting the  water. 

5218.  The  most  efficient  mode  of  obtaining  this  acid 
pure,  is  to  saturate  the  juice  of  lemons  with  chalk  or 
whiting,  and  afterwards  to  decompose  the  citrate  of  lime 
thus  formed,  by  sulphuric  acid,  duly  diluted.     The  citric 
acid  may  be  obtained  in  crystals,  from  the  supernatant  li- 
quid, by  evaporation. 

5219.  Citric  acid  is  crystallizable.     Its  taste  is  intense- 
ly acid  when  concentrated,  but  agreeably  sour  when  dilute. 

5220.  It  is  a  tribasic  acid;  its  formula,  when  dried  at 
212°,  being  represented  by  C12  H5  O11  +  3HO.     The  atoms 
of  water  are  essential  to  the  composition  of  the  acid  in  its 
free  state,  and  cannot  be  removed  unless  by  substitution 
of  an  equivalent  number  of  atoms  of  some  other  base. 

5221.  Malic  acid  derives  its  name  from  the  apple,  as 

*  From  thp  fruit  of  the  genus  citrus,  including  the  orange,  citron,  lemon,  lime, 
and  shaddock. 


462  ORGANIC  CHEMISTRY. 

in  this  fruit  it  predominates,  as  well  as  in  gooseberries, 
currants,  and  other  similar  fruits.  It  may  be  had  pure  by 
saturating  lime  with  apple  juice,  and  decomposing  the  ma- 
late  of  lime  by  sulphuric  acid. 

5222.  Professor  Wm.  Rogers,  of  the  University  of  Vir- 
ginia, has  ascertained  that  this  acid  abounds  in  different 
species  of  sumach,  in  the  state  of  bimalate  of  lime.     Malic 
acid  is  bibasic,  its  formula  being  C5  H4  O8  +  2HO. 

5223.  Malic  and  citric  acids  afford  very  good  examples  of  the  operation  of 
a  law,  to  which  a  great  many  of  the  vegetable  acids  are  subjected.    At  a  tem- 
perature a  little  above  that  at  which  they  melt,  they  severally  yield  new  acids* 
That  yielded  by  citric'acid,  is  identical  with  the  acid  found  in  the  aconitum 
napellus,  and  also  the  various  species  of  equisitum.     Hence,  it  has  received 
the  name  of  aconitic  or  equisitic  acid.     Whether  obtained  from  citric  acid 
by  heat,  or  from  either  of  its  other  sources,  it  exists  in  the  form  of  white 
crystals,  soluble  in  water,  and  sour  in  taste.     The  acid  into  which  malic 
acid  is  changed,  under  similar  circumstances,  is  also  found  in  nature  in  the 
Iceland  moss,  and  in  the  fumaria  officinalis.     Hence  it  has  been  called  fu- 
maric  acid,  although  Pelouze,  who  first  obtained  it  from  malic  acid  by  heat, 
.called  it  paramalic  acid.     Both  of  these  acids  differ  from  the  citric  and 

malic  acid,  from  which  they  are  produced,  only  in  having  lost  the  elements 
of  two  atoms  of  water. 

5224.  When  either  of  the  acids  thus  obtained,  by  heating  citric  or  malic 
acid,  is  exposed  to  a  higher  temperature,  a  further  change  takes  place,  and 
volatile  acids  are  formed,  fumaric  acid  yielding  malic,  and  aconitic  producing 
itaconic  acid.    The  former  would  seem  to  be  formed  by  a  mere  transposition 
of  the  elements  of  water  present,  which  appear  as  two  atoms  of  water  of  crys- 
tallization, instead  of  entering  as  before  as  two  basic  atoms  into  the  integral 
composition  of  the  acid.     A  farther  application  of  heat  converts  itaconic 
into  citraconic  acid ;  while  malleic  acid,  if  kept  in  a  state  of  fusion  for  a 
length  of  time,  reverts  to  the  condition  of  furnaric  acid. 

5225.  It  must  be  observed,  that  if  citric  or  malic  acid  be  heated,  without 
keeping  them  at  the  temperatures  necessary  for  the  formation  of  the  acid 
compounds  which  they  respectively  produce,  the  result  will  be  a  mixture  in 
the  one  case  of  fumaric  acid  and  malic  acid,  in  the  other,  of  aconitic,  ita- 
conic and  citraconic  acids. 

Of  Tartaric  Acid,  and  Paratartaric  or  Racemic  Acid. 

5226.  Tartaric  acid  is  found  in  many  vegetables.  It  is 
named  from  tartar,  an  appellation  given  to  a  deposition 
from  wine,  which  contains  this  acid  united  with  potash  arid 
water.  This  tartrate,  when  freed  from  impurities,  is  known 
officinally  under  the  name  of  cream  of  tartar.  When  to 
twenty-four  parts  of  this  salt,  thirteen  of  carbonate  of  soda 
are  added,  sal  Rochelle,  a  tartrate  of  potash  and  soda,  is 
produced ;  and  in  like  manner,  tartar  emetic,  by  replacing 
the  basic  water  by  the  sesquioxide  of  antimony.  Another 
pharmaceutical  compound,  called  tartarized  iron,  is  pro- 


OP  TARTARIC  ACID.  463 

duced  by  replacing  the  water  of  cream  of  tartar  by  iron, 
which  is  taken  up  in  the  state  of  protoxide,  but  becomes, 
by  exposure,  more  or  less  sesquioxidized. 

5227.  Tartaric  acid  is  procured  from  cream  of  tartar  in 
fine  crystals,  by  adding  chalk  until  effervescence  ceases, 
and  decomposing  the  precipitate  by  diluted  sulphuric  acid. 
The  neutral  tartrate  of  potash  left,  may  be  decomposed  by 
quicklime  or  chloride  of  calcium,  and  the  resulting  tartrate 
of  lime  will  yield  the  acid  in  the  same  way  as  the  analo- 
gous tartrate,  obtained  in  the  first  instance  by  the  addition 
of  chalk. 

5228.  Tartaric  acid  is  extremely  sour,  and  reddens  lit- 
mus.    It  is  bibasic,  its  formula  being  C8  H4  OJO  +  2HO. 
In  consequence  of  this  bibasic  character,  the  salts  which  it 
forms  with  one  atom  of  a  fixed  base  are  sour,  have  an  acid 
reaction,  and  require  the  presence  of  an  atom  of  basic 
water.     Thus  the  salt  heretofore  described  as  the  bitar- 
trate  of  potash,  must  now  be  considered  as  the  tartrate  of 
potash  and  water,  since  it  consists  of  one  atom  of  tartaric 
acid,  one  atom  of  potash,  and  an  atom  of  basic  water. 

5229.  Of  Paratartaric  or  Racemic  Acid. — A  manufac- 
turer of  Thann,  in  Germany,  in  preparing  tartaric  acid 
from  cream  of  tartar,  which  had  been  deposited  from  the 
wine  of  that  country,  discovered  an  acid  differing  from 
that  which  it  was  his  object  to  procure,  and  which  he  sup- 
posed to  be  the  oxalic.     Gay-Lussac  subsequently  proved, 
that  while  possessed  of  peculiar  qualities,  its  equivalent 
was  the  same  as  that  of  tartaric  acid.     By  Berzelius  it 
was  afterwards  shown  to  be  isomeric  with  this  last  men- 
tioned acid,  and  he  has  consequently  named  it  paratar- 
taric  acid.     The  appellation  of  racemic,  has  also  been  ap- 
plied to  it.     Paratartaric  acid  crystallizes  in  a  different 
form  from  tartaric  acid  proper.     It  is  likewise  less  solu- 
ble. 

5230.  The  action  of  heat  on  tartaric  acid  is  strikingly  peculiar.     At  a 
temperature  merely  sufficient  to  produce  fusion,  two  atoms  of  the  acid  give 
off  one  of  the  four  atoms  of  the  basic  water  combined  with  them,  losing  at 
the  same  time  one  fourth  of  their  saturating  power,  and  causing  the  acid  to 
become  sesquibasic,  so  that  two  atoms  of  it  saturate  only  three  of  base. 
The  name  of  tartralic  has  been  applied  to  the  acid  in  this  state. 

5231.  A  still  further  application  of  heat  removes  another  half  atom  of 
water  and  produces  tartrelic  acid,  which  is  monobasic,  saturating  only  one 
atom  of  base,  and  requiring  in  the  free  state  the  presence  of  but  one  atom 
of  water.     A  still  higher  temperature  removes  all  basic  water,  and  leaves  a 
porous  white  mass,  insoluble  in  water,  and  hence  no  longer  sour  or  capable 


464  ORGANIC  CHEMISTRY. 

of  reddening  litmus.  The  composition  of  this  body  is  C8  H4  O10.  Conse- 
quently, it  is  identical  with  that  of  tartaric  acid  freed  from  its  basic  water, 
as  it  exists  for  instance  in  the  bibasic  tartrate  of  lead.  If  left  long  in  con- 
tact with  the  water,  this  insoluble  compound  gradually  takes  up  two  atoms 
of  the  oxide  of  hydrogen,  and  becomes  the  ordinary  soluble  bibasic  tartaric 
acid.  It  has  been  considered,  that  the  absence  of  sourness,  in  this  only  in- 
stance of  an  isolated  anhydrous  organic  acid,  is  favourable  to  the  idea  that 
oxacids  are  hydrurets  of  compound  radicals  owing  their  acid  reaction  to 
hydrogen;  but  it  should  be  recollected,  that  the  absence  of  this  action  is  an 
invariable  consequence  of  insolubility.  No  insoluble  hydruret  of  which 
there  are  instances  among  the  oils  or  etherial  compounds  is  sour.  Nor  is 
it  that  portion  of  water  which  enters  the  tartaric  acid  as  a  base,  and  on  the 
hydrogen  of  which  the  hypothesis  relies,  which  confers  either  sourness  or 
the  capacity  for  acid  reaction  with  vegetable  colours.  Independently  of 
moisture,  the  gaseous  hydracids,  erroneously  so  called,  have,  I  believe,  no 
such  properties. 

5232.  Of  Liquid  and  Solid  Pyrotartaric  Acid. — By  destructive  distil- 
lation, tartaric  acid  yields  two  acids,  to  which  the  preceding  appellations 
have  been  given.     Liquid  pyrotartaric  acid  forms  a  monobasic  ether,  and 
various  salts.     Its  formula  is  C8  H3  O5.     Solid  pyrotartaric  acid  is  gene- 
rated in  small  proportion,  during  the  destructive  distillation  of  tartaric  acid ; 
but  is  yielded  more- copiously  by  subjecting  cream  of  tartar  to  that  process. 
Graham,  948. 

Of  Guiacine,  or  Guiacinic  Acid. 

5233.  In  the  Journale  de  Pharmacie,  for  1842,  p.  386,  notice  is  given  by 
J.  Pelletier,  of  the  results  of  an  investigation,  which,  though  it  had  not  been 
completed,  enabled  him  to  allege  that  the  peculiar  principle  of  gum  guiacum, 
which  he  calls  guayacine,  in  English  guiacine,  may  be  isolated  by  either 
of  two  processes.     According  to  one,  an  alcoholic  solution  of  acetate  of 
lead  is  to  be  added  in  successive  portions  to  a  tincture  of  the  resin,  reject- 
ing the  latter  portions  of  the  precipitates  formed.    The  compound  thus  pro- 
cured, is  to  be  well  washed  with  water  first,  and  afterwards  with  alcohol. 
Then  being  suspended  in  water,  is  to  be  exposed  to  sulphydric  acid,  by 
which  the  lead  is  precipitated  as  a  sulphide.     The  guiacine  is  then  taken 
up  by  alcohol. 

5234.  According  to  the  other  process,  hydrate  of  lime  is  added  to  the 
tincture,  by  which  means  a  compound,  of  the  guiacine  and  lime,  is  obtained. 
From  this  the  guiacine  may  be  easily  extricated. 

5235.  Guiacine  has,  in  a  high  degree,  the  property  of  becoming  blue  by 
absorbing  oxygen,  and,  after  being  thus  coloured,  may  be  restored  to  its 
previous  state  by  substances  greedy  of  oxygen,  such  as  sulphydric  or  sul- 
phurous acid,  protoxide  of  iron,  or  protochloride  of  tin.     Re-exposure  to 
the  air  restores  the  blue  colour. 

5236.  Moist  chlorine,  or  an  aqueous  solution  of  this  gas,  turns  guiacine 
blue;  but  an  excess  renders  it  green,  and  yellow,  successively.     From  the 
last  mentioned  state  it  cannot  be  restored,  having  undergone  a  chemical 
change. 

5237.  Notwithstanding  the  property  of  combining  with  bases,  Mr.  Pelle- 
tier hesitated  to  designate  it  as  an  acid,  but  in  this,  as  it  was  found  to  com- 
bine with  bases,  I  consider  him  as  misjudging.     The  analogy  between  this 
resin  and  indigd,  as  respects  changes  of  Colour,  must  strike  every  one  ac- 
quainted with  the  facts. 


OF  TANNIC  ACID.  465 

5238.  I  presume  in  English  the  principle  which  he  has  isolated,  will  be 
called  guaicine ;  or  if  it  be  an  acid,  as  from  the  account  given,  it  evidently 
ought  to  be  considered,  the  name  will  be  guaicinic  acid. 

Of  Tannic  Acid. 

5239.  From  its  formula,  C18  H5  O9  +  3HO,  it  may  be 
seen  that  the  tannic  acid  is  tribasic. 

5240.  The  art  of  converting  the  hides  or  skins  of  ani- 
mals into  leather,  by  soaking  them  in  infusions  of  the  bark 
of  oak  and  other  trees,  had  long  been  practised.     Subse- 
quently it  was  ascertained  that  this  change  arose  from  a  che- 
mical combination  ensuing  between  the  gelatin  of  the  skin 
or  hide,  and  a  vegetable  principle  called  tannin,  from  its  ef- 
ficiency in  the  process  of  tanning  abovementioned.     Ber- 
zelius  first  treated  of  tannin  as  an  acid.     This  view  being 
adopted,  the  principle  is  now  universally  designated   as 
tannic  acid.     It  is  peculiarly  abundant  in  oak  galls,  giving 
to  an  infusion  of  them  the  property  of  causing,  with  iron, 
an  ink  colour,  whence  its  use  as  an  ingredient  of  common 
writing  ink. 

5241.  Tannic  acid  is  likewise  found  in  a  great  number 
of  vegetables,  generally  in  their  bark  or  roots,  but  not  un- 
frequently  in  their  leaves  and  seeds,  and  even  in  their  flow- 
ers and  fruits,  before  they  have  reached  maturity.     It  is, 
in  fact,  the  most  frequent  cause  of  astringency  in  vegetable 
products. 

5242.  It  may  be  procured,  according  to  Mr.  Pelouze,  in 
a  state  of  purity,  by  introducing  powdered  galls  into  a  ves- 
sel, with  a  body  and  pipe  resembling  that  of  a  funnel,  but 
contracted  above  into  a  neck  like  that  of  a  bottle.     The 
pipe  of  this  vessel  should  be  furnished  with  a  cock,  and 
must  be  made  to  descend  into  a  tincture  bottle  through 
the  mouth.     The  galls  are  then  to  be  covered  with  sul- 
phuric ether,  of  the  officinal  strength,  and  the  mouth  of  the 
vessel  being  corked,  they  are  to  be  left  in  contact  with  the 
ether  for  several  hours.     The  liquid  being  then  allowed  to 
descend  into  the  bottle,  will  be  found  to  separate  into  two 
portions,  of  which  the  heaviest  is  a  solution  of  tannic  acid. 
From  this  solution  the  acid  may  be  obtained  in  the  solid 
form  by  washing  with  ether,  and  evaporation,  in  vacuo, 
over  sulphuric  acid.     Thus  obtained,  it  is  inodorous,  as- 
tringent, yellowish  white,  and  somewhat  crystalline. 

5243.  The  oxides  of  the  following  metals  form  insoluble 


466  ORGANIC  CHEMISTRY. 

tannates,  and  hence  yield  precipitates  with  tannic  acid,  or 
an  infusion  of  galls.  The  colours  of  these  precipitates  are 
as  follows : — 

The  precipitate  formed  with  lead  or  antimony,  white. 

With  tin,  nickel,  cobalt,  silver,  various  shades  of  yellow. 

With  tantalum  or  bismuth,  orange. 

With  titanium,  blood  red. 

With  platinum,  green. 

With  chrome,  molybdenum,  uranium,  and  gold,  brown. 

With  osmium  and  sesquioxide  of  iron,  deep  purple,  blue, 
or  ink  colour. 

5244.  On  account  of  the  insolubility  of  the  tannate  of 
antimony,  an  infusion  of  galls,  or  of  oak  bark,  is  an  anti- 
dote for  tartar  emetic  and  other  antimonial  preparations. 

5245.  Tannic  acid  has  also  been  found  a  test  for,  and 
precipitant  of,  the  organic  alkalies,  and  must  be  more  or 
less  an  antidote  for  their  poisonous  influence. 

5246.  The  aqueous  solution  of  tannic  acid  reddens  lit- 
mus.    It  does  not  affect  solutions  of  the  protoxide  of  iron; 
and  the  intense  colour  produced  as  abovementioned,  with 
the  sesquioxide,  may  be  removed  by  reagents,  which  re- 
duce the  iron  to  the  state  of  protoxide,  as  already  illus- 
trated (1817). 

5247.  Ink  is  best  made  with  the  green  sulphate  of  iron, 
because,  so  long  as  the  iron  is  not  sesquioxidized,  remain- 
ing in  solution,  it  can  penetrate  the  paper  better ;  and  it 
soon  peroxidizes,  and  consequently  blackens,  by  exposure 
to  the  atmospheric  oxygen.     (Ure.) 

5248.  By  a  piece  of  raw  hide,  pure  tannic  acid  may,  in 
a  few  hours,  be  taken  up  from  a  solution  so  completely, 
that  if  no  gallic  acid  be  present,  the  liquid  will  not  be  af- 
fected by  a  solution  of  sesquioxide  of  iron. 

5249.  According  to  Graham,  tannic  acid  precipitates  a 
solution  of  starch  and  albumen,  and  is  capable  of  com- 
bining with  animal  fibrin. 

5250.  Of  Artificial  Tannin. — A   substance  resembling 
tannic  acid  in  many  of  its  properties,  and  called,  gene- 
rally, artificial  tannin,  is  formed  during  the  action  of  ni- 
tric or  sulphuric  acid  on  a  great  variety  of  vegetable  sub- 
stances.   One  variety  of  this  tannin  is  formed  by  the  reac- 
tion of  nitric  acid  with  charcoal. 


OF  GALLIC  ACID.  467 

Of  Gallic  Acid. 

5251.  Formula  of  the  dry  acid,  C7  HO3  2HO.    When 
crystallized,  one  additional  atom  of  water  is  present. 

5252.  This  acid  and  tannic  acid  appear  to  be  almost 
always  more  or  less  associated;  so  that  they  are  generally 
both  present,  where  either  is  found.    This  is  now  explained 
by  the  fact,  that  tannic  acid  is  liable  to  be  converted  into 
gallic  acid  spontaneously. 

5253.  Agreeably  to  one, of  the  processes  recommended 
for  procuring  the  last  mentioned  acid,  nut  galls,  made  into 
a  paste  with  water,  are  to  be  exposed  to  the  air  for  seve- 
ral weeks  at  the  temperature  of  80°  nearly,  water  being 
supplied  so  as  to  compensate  for  evaporation.     The  re- 
sulting mass  is  to  be  subjected  to  boiling  water,  and  the 
solution  thus  obtained  being  filtered,  the  gallic  acid  sepa- 
rates in  the  crystalline  form.     It  is  rendered  quite  pure  by 
re-solution,  digestion  with  animal  charcoal,  and  re-crystal- 
lization. 

5254.  If  the  precipitate,  obtained  by  adding  sulphuric 
acid  to  a  concentrated  extract  of  galls,  be  washed  with  a 
small  quantity  of  water,  and  then  dissolved  by  gradually 
adding  it  to  a  boiling  solution  of  one  part  of  sulphuric  acid 
in  two  of  water,  gallic  acid  is  generated,  and,  by  refrige- 
ration, separates  from  the  liquid  in  crystals.     The  impure 
acid  thus  isolated,  may  be  purified  partially  by  re-solution 
and  crystallization;  or  more  thoroughly  by  adding  to  a 
solution  of  it  acetate  of  lead,  and  decomposing  the  result- 
ing insoluble  gallate  of  the  protoxide  of  lead,  by  sulphydric 
acid  (899).     By  these  means  the  lead  is  converted  into  a 
sulphide,  which  separates  this  metal,  and  much  colouring 
matter,    simultaneously;    the    acid    remaining    dissolved. 
Graham,  941. 

5255.  Again,  if  tannic  acid  be  subjected,  for  a  few  mi- 
nutes, to  a  solution  of  caustic  potash,  on  the  addition  of 
sulphuric  acid  in  excess,  crystals  of  gallic  acid  will  be  co- 
piously formed  on  the  cooling  of  the  liquid.     Kane,  1010. 

5256.  Gallic  acid  crystallizes  from  a  hot  solution  in  thin 
silky  needles,  which,  for  solution,  require  100  parts  of  cold 
water,  although,  when  boiling,  three  parts  are  sufficient. 
It  is  very  soluble  in  alcohol,  and  sparingly  soluble  in  ether. 
Although  it  is  productive  of  the  same  changes  in  solutions 

60 


468  ORGANIC  CHEMISTRY. 

of  sesquioxide  of  iron  as  tannic  acid,  it  differs  from  it  in 
not  causing  any  precipitate  in  solutions  of  gelatine. 

5257.  It  would  appear  doubtful  whether  this  acid  exists 
ready  formed  in  nature,  or  whether  it  be  not  always  a  pro- 
duct of  the  oxidation,  or  partial  decomposition  of  tannic 
acid.     It  has  been  stated,  that  the  exposure  of  the  latter 
to  the  air,  or  boiling  it  with  an  excess  of  alkali,  without 
the  presence  of  the  atmosphere,  produces  this  change; 
and  that  it  may  also  be  effected  by  means  of  sulphuric 
acid. 

5258.  On  the  one  hand  it  has  been  observed,  that  three 
atoms  of  tannic  acid  contain  the  elements  of  six  atoms  of 
gallic  acid,  and  one  of  grape  sugar;  and  on  the  other,  that 
the  absorption  of  eight  atoms  of  oxygen  would  convert  an 
atom  of  tannic  acid  into  four  atoms  of  carbonic  acid  and 
two  of  crystallized  gallic  acid.     As,  according  to  Bracon- 
not,  alcohol  and  carbonic  acid  have  been  evolved  from  nut- 
galls  during  their  fermentation,  it  seems  possible  that  tan- 
nic acid  may  be  produced,  according  to  circumstances, 
either  by  fermentation,  or  by  the  oxidation  of  the  princi- 
ples present  in  nut-galls.     Indeed,  tannic  acid  itself  would 
appear,  from  the  nature  of  the  sources  from  which  it  is 
obtained,  to  be,  in  many  instances,  the  result  of  a  gradual 
decay  of  other  principles  in  plants;  and  when  gallic  acid, 
either  in  its  free  state,  or  as  it  exists  in  the  gallates,  is  ex- 
posed to  the  air,  it'  undergoes  a  still  further  change  into 
carbonic  acid,  and  a  brown  vegetable  substance.     Hence 
it  may  be  conjectured,  that  both  of  the  acids  in  question 
are  the  products  of  different  stages  of  one  continued  trans- 
formation. 

5259.  If  gallic  acid  be  heated  to  about  400°,  it  is  decomposed  into  car- 
bonic acid,  and  a  new  acid  which  sublimes  in  brilliant  white  plates.     This 
acid  has  received  the  name  of  pyrogallic,  and  is  soluble  in  water,  alcohol, 
and  ether.     If,  on  the  contrary,  the  heat  be  raised  above  450°,  an  insoluble 
black  mass  remains  in  the  retort,  to  which,  from  its  combining  with  alka- 
lies, and  its  colour,  the  name  of  melangallic  acid  has  been  given.     These 
results  are  only  worthy  of  notice  as  forming  part  of  a  series  of  transforma- 
tions which  most  of  the  organic  acids  undergo  through  the  application  of 
heat. 

5260.  An  acid,  called  the  elagic,  is  frequently  produced  during  that  ex- 
posure of  galls  to  the  air,  which  gives  rise  to  the  formation  of  gallic  acid. 
There  are  several  species  of  vegetable  products  in  which  acids,  resembling 
the  gallic  and  tannic  acids,  though  not  identical  with  them,  have  been  dis- 
covered.    Thus,  in  the  bark  of  the  various  species  of  cinchona,  combined 
with  quinia  or  cinchona,  are  found  two  acids,  the  cinchonic  and  cinchona- 


OF  MECONIC  ACID.  469 

tannic,  whose  physical  properties  stand  in  very  nearly  the  same  relation  to 
each  other  as  that  borne  by  gallic  and  tannic  acid ;  and  in  catechu,  an  ex- 
tract obtained  from  the  mimosa  catechu,  there  have  been  discovered  two 
acids,  the  catechuic  and  the  catechutannic,  of  which  nearly  the  same  state- 
ment may  be  made.  It  does  not  appear,  however,  that  in  either  case  one 
of  them  has  the  property  of  being  converted  into  the  other,  as  is  the  case 
with  tannic  and  gallic  acids.  Berzelius,  however,  is  of  the  opinion,  that  all 
the  forms  of  tannic  acid  found  in  plants  are  identical  in  composition,  but 
modified  by  association  with  other  matter. 

Of  Meconic  Acid. 

5261.  Formula,C14HOn+3HO;  when  crystallized +  6HO. 
Meconic  acid  is  tribasic. 

5262.  When  a  solution  of  acetate  of  lead  is  added  to  an 
infusion  of  opium,  a  precipitate  is  obtained,  consisting  of 
meconate  of  lead.    From  this  the  lead  may  be  precipitated 
as  a  sulphide  by  means  of  sulphydric  acid,  and  a  solu- 
tion of  the  liberated  meconic  acid  obtained  by  filtration. 
This  acid  exists  in  opium,  combined  with  morphia  and 
codeia. 

5263.  With  solutions  of  the  sesquioxide  of  iron,  meconic 
acid  produces  an  intense  red  colour;  with  protoxide  of  lead 
an  insoluble  precipitate.     It  is  to  this  affinity,  for  oxidized 
lead,  that  we  owe  the  process,  above  described,  for  pro- 
curing this  acid. 

5264.  Meconic  acid  produces  a  taste,  at  first  sour,  and 
subsequently  bitter,  and  reddens  litmus  paper.     Being  a 
tribasic  acid,  it  forms  three  classes  of  salts,  in  which  the 
water  present  may  be  replaced,  partially  or  entirely,  by 
one,  two,  or  three  atoms  of  base.     Like  other  organic 
acids  which  have  been  described,  meconic  acid  is  converted 
by  heat  into  another  acid,  the  komenic,  carbonic  acid  being 
evolved;  and  as  this  komenic  acid  cannot  be  volatilized,  it 
is,  at  a  higher  temperature,  converted  into  pyromeconic 
acid,   which   may  be   sublimed   without   further   change. 
Each  of  these  transformations  is  accompanied  by  the  loss 
of  an  atom  of  basic  water,  and  a  diminished  capacity  of 
saturating  bases. 

Of  a  Method  of  detecting  the  Presence  of  Opium. 

5265.  The  property  which  meconic  acid  has  of  precipi- 
tating with  lead,  and  of  producing  a  red  colour  with  iron, 
may  enable  us  to  detect  opium,  when  present  in  a  very 
small  quantity  in  solution. 


470  ORGANIC  CHEMISTRY. 

5266.  If  ten  drops  of  the  tincture  of  opium,  commonly 
called  laudanum,  be  mingled  with  half  a  gallon  of  water, 
on  adding  a  few  drops  of  subacetate  of  lead,  there  will  be  a 
precipitation  which,  at  the  end  of  a  few  hours,  will  be  per- 
ceptible in  flocks.     The  descent  of  these  flocks  may  be  ac- 
celerated by  detaching  them  gently  from  the  sides  of  the 
recipient  with  a  glass  rod.     The  vessel  should  be  conical, 
so  as  to  concentrate  them  during  their  descent.     After 
they  are  collected  at  the  bottom  of  the  vessel,  about  30 
drops  of  the  red  sulphate  of  iron,  and  an  equivalent  portion 
of  sulphuric  acid  should  be  introduced  among  them  by 
means  of  a  small  glass  tube.     The  presence  of  the  me- 
conic  acid  will  be  rendered  evident  by  the  redness  which 
ensues. 

5267.  When  a  red  colour  is  produced  by  the  means 
here  described,  it  is  probable  that  opium  is  present;  as  me- 
conic  acid  is  found  only  in  that  drug,  and  having  no  active 
qualities,  is  not  used  separately  from  it  in  any  pharmaceu- 
tical preparation. 

5268.  It  may  be  proper  to  mention,  that  sulphocyanhy- 
dric  acid  produces,  with  the  sesquioxide  of  iron,  a  colour 
resembling  that  produced  by  meconic  acid. 

Of  the  Acids  formed  from  Sugar. 

5269.  Cane  sugar  may  be  made  to  combine,  as  sugar,  with  the  alkaline 
earths,  and  with  some  of  the  metallic  oxides,  though  not  with  the  alkalies. 
In  these  compounds  the  sugar  exists  unchanged,  but  united  to  the  base  by 
an  affinity  so  feeble,  that  it  may  be  displaced  by  carbonic  acid. 

5270.  Nevertheless,  if  sugar  be  kept  a  long  time  dissolved  in  an  alkaline 
solution,  it  undergoes  a  transformation  into  a  real  acid,  the  glucic  acid, 
which  has  a  sour  taste  when  free,  and  combines  with  bases  to  form  salts. 
In  this  acid,  as  in  lactic  acid,  the  oxygen  and  hydrogen  are  present  in  the 
proportion  for  forming  water;  and  the  only  change  which  sugar  experiences 
by  conversion  into  glucic  acid,  is  the  loss  of  several  atoms  of  water.     The 
formula  for  glucic  acid  would  appear  to  be  C12  H8  O8. 

5271.  If  heat  be  applied  to  a  solution  of  sugar  with  an  alkaline  base, 
melassic  acid  is  produced  either  from  the  sugar  directly,  or  from  the  glucic 
acid.     It  is  said  to  consist  of  C24  H12  O10,  so  that  in  forming  it,  sugar  parts 
not  only  with  water,  but  also  with  oxygen. 

5272.  By  the  reaction  of  diluted  nitric  acid  with  sugar,  a  crystallizable 
acid  of  a  strong  sour  taste  is  produced.     It  was  at  first  supposed  to  be  malic 
acid,  but  was  afterwards  distinguished  by  the  name  of  oxalhydric.     It  is 
now  called  saccharic  acid.     Its  formula  is  C13  H5  O14  5HO.     The  five 
atoms  of  water  are  essential  to  the  composition  of  the  acid  in  what  is  called 
the  free  state.     When  it  is  united  to  other  bases,  the  water  is  replaced, 

^wholly  or  in  part,  by  a  corresponding  number  of  atoms  of  base.     The  an- 
hydrous salt  which  it  forms  with  lead,  consists  of  C12  H5  O11  +  5PbO ; 


OF  FORMIC  ACID.  471 

and  by  its  union  with  the  oxide  of  that  metal,  it  forms  three  other  salts,  in 
which  we  find  C13  H5  O11  combined,  respectively,  with  3PbO  +  2HO,  2PbO 
+  3HO,  and  PbO  +  4HO.  These  facts  respecting  the  composition  of  the 
saccharates  are  instructive,  as  furnishing  support  to  the  theory  of  poly- 
basic  acids  ;  since,  if  we  do  not  have  recourse  to  that  theory,  we  must  sup- 
pose the  existence  of  a  distinct  acid  in  each  of  the  salts  above  mentioned,  and 
that  one  of  them  has  the  property  of  combining  with  five  atoms  of  base,  and 
not  with  any  smaller  quantity. 

5273.  When  lactin  (sugar  of  milk,  4070)  is  subjected  to  the  action  of 
diluted  nitric  acid,  mucic  acid  is  produced.  It  may  also  be  obtained  by 
substituting  gum,  or  mannite,  for  the  sugar  of  milk.  It  exists  as  a  crystal- 
line powder  of  difficult  solubility,  and  a  feebly  acid  taste.  Its  formula  is 


Of  Formic  Acid. 

5274.  It  is  inferred,  that  between  formic  acid,  formyl 
(4019),  and  methyl  (4016),  the  same  relation  exists  as  be- 
tween acetic  acid,  acetyl,  and  ethyl;  and  also  that  the  part 
performed  by  alcohol,  the  hydrated  oxide  of  ethyl,  in  the 
one  case,  is  performed  by  pyroxylic  spirit,  the  hydrated 
oxide  of  methyl  in  the  other.    Either  the  methylic,  or  ethy- 
lic  alcohol,  by  losing  two  atoms  of  hydrogen,  and  acquiring 
two  of  oxygen,  are  converted,  the  one  into  acetic,  the  other 
into  formic  acid.    Moreover,  the  same  catalytic  agent,  pla- 
tinum sponge,  or  black,  may  in  either  case  be  competent 
to  induce  the  requisite  reaction  with  atmospheric  oxygen. 
The  features  which  are  wanting  to  complete  the  resem- 
blance, are  congeners  severally  of  aldehyde,  C4  H3O  +  HO, 
and  acetous  acid,  C4  H3  O2  +  HO.     To  correspond  with 
these  compounds,  no  hydrated  oxide  of  formyl,  nor  formous 
acid,  are  known. 

5275.  To  render  this  statement  more  intelligible,  the 
following  formulae  are  subjoined.     Methyl,  C2  H3;  formyl, 
C2  H;  anhydrous  formic  acid,  C2  HO3.     To  form  the  hy- 
drated acid,  one  atom  of  water,  HO,  must  be  added. 

5276.  Formic  acid  was  originally  obtained  from  ants. 
It  appears  to  exist  in  them  naturally. 

5277.  This  acid  may  be  obtained  by  adding  to  one 
part  of  sugar  in  an  alembic,  three  parts  of  well  pulverized 
peroxide  of  manganese,  and  three  parts  of  sulphuric  acid 
diluted  with  its  weight  of  water.     The  acid   should   be 
added  in  three  successive  portions.     At  first,  the  efferves- 
cence is  so  great  as  to  require  the  vessel  to  have  fifteen 
times  the  capacity  which  would  be  necessary  to  contain 
the  material  when  quiescent.     The  formic  acid  associated 


472  ORGANIC  CHEMISTRY. 

with  formic  ether,  is  brought  over  by  distillation.  It  may 
be  saturated  with  chalk  or  an  alkali,  and  the  resulting 
formiate  decomposed  and  isolated  by  distillation  with  ten 
parts  by  weight  of  sulphuric  acid,  diluted  with  four  of 
water. 

5278.  According  to  the  late  Professor  Emmet,  the  pre- 
sence of  peroxide  of  manganese  in  this  process  is  unneces- 
sary.    Agreeably  to  his  observations,  the  conversion  of 
many  vegetable  substances  into  formic  acid,  among  others 
maize,   may  be  effected  by  any  of  those  agents  which 
would  effect  the  evolution  of  ether  from  alcohol. 

5279.  From  the  investigations  of  Dobereiner,  it  ap- 
pears that  formic  acid  is  an  excellent  reagent  for  separat- 
ing the  noble  metals  from  solutions  in  which  they  are  in- 
termingled with  other  metals  proper.     If  a  solution  con- 
taining one  or  more  noble  metals,  be  elevated  nearly  to  the 
temperature  of  ebullition,  on  adding  an  alkaline  formiate, 
the  noble  metals  will  be  immediately  and  entirely  precipi- 
tated in  a  very  minute  state  of  division.    At  the  same  time, 
by  ascertaining    the   weight  of  the   gas    simultaneously 
evolved,  that  of  the  metal  thrown  down  may  be  deter- 
mined. 

5280.  From  its  solution  in  water,  the  bichloride  of  mer- 
cury is  converted  into  calomel  with  so  much  facility,  and 
in  a  state  of  division  so  perfect,  by  formic  acid  or  formiate 
of  soda,  that  their  employment  in  the  preparation  of  that 
protochloride  was  suggested  by  Dobereiner. 

5281.  If  the  same  quantity  of  sulphuric  acid  and  man- 
ganese be  mingled  with  six  parts  of  alcohol,  the  process 
being,  in  other  respects,  the  same  as  that  for  formic  acid 
above  described,  formic  ether  becomes  the  predominant 
product.    It  is  freed  from  formic  acid  by  magnesia,  from 
alcohol  by  a  small  quantity  of  water,  and  from  water  by 
chloride  of  calcium.     By  a  more  extensive  contact  with 
water,  formic  ether  is  decomposed,  and  alcohol  and  formic 
acid  are  generated. 

5282.  Formic  acid  has  a  pungent  taste,  and  a  peculiar 
sharp  odour.     It  is  more  energetic  in  its  affinities  than 
acetic  acid.     The  formiates,  like  the  acetates,  are  gene- 
rally very  soluble. 


OF  MODIFIED  ACIDS.  473 


Of  Valerianic  Acid,  O°  H»  O3  +  HO. 

5283.  This  acid  was  described  in  the  last  edition  of  this  Compendium, 
as  a  product  yielded  by  the  root  of  valerian,  (valeriana  officinalis,)  when 
subjected  to  distillation  with  water.      Since  that  time,  it  has  been  found  to 
be  producible,  artificially,  from  a  totally  different  source.     It  has  been  dis- 
covered by  Cahours,  that  if  oil  of  potato  spirit  (hydrated  oxide  of  amyl, 
4023),  be  allowed  to  fall  in  successive  drops  no  faster  than  it  can  be  im- 
bibed upon  platinum  black,  previously  heated,  an  acid  vapour  arises  from 
the  oxidation  of  the  elements  of  the  oils,  which  has  all  the  properties  of 
the  valerianic  acid,  obtained  from  the  root  of  valerian  as  above  mentioned. 

5284.  During  this  process,  two  atoms  of  hydrogen  are  replaced  by  two 
atoms  of  oxygen,  so  that  it  is  quite  analogous  to  the  play  of  affinities  by 
which  the  acetic  and  formic  acids  are  generated ;  the  former  from  alcohol, 
the  latter  from  pyroxylic  spirit. 

5285.  Valerianic  acid  is  also  generated  in  potato  spirit,  by  the  sponta- 
neous absorption  of  atmospheric  oxygen  by  exposure  to  the  air. 

5286.  Valerianic  acid  is  a  colourless  liquid,  having  an  oleaginous  con- 
sistency, a  sharp,  acid  taste,  and  a  persistent  odour,  which  recalls  that  of 
the  root  of  valerian.     In  the  state  of  protohydrate,  according  to  Graham, 
it  produces  a  white  spot  upon  the  tongue  when  applied  to  it.     The  density 
of  this  acid  is  nearly  937  at  62°.     It  boils  without  alteration  at  347°,  and 
remains  liquid  at  5°.     When  heated  in  a  platinum  spoon  it  takes  fire  rea- 
dily, burning  with  a  white  flame  and  much  smoke,  leaving  little  residue. 
It  is  soluble  in  eighty  times  its  weight  of  cold  water,  and  in  all  proportions 
in  alcohol.     It  is  capable  of  taking  up  20  per  cent,  of  water  without  losing 
its  oily  consistence. 

5287.  From  the  formula  of  this  acid  it  is  supposed,  that  it  may  consist 
of  a  compound  radical  analogous  to  acetyl,  for  which  the  name  valeryl  is 
suggested;  formula,  C10  H9. 

Of  Cafeic  Acid  and  Cafee  Tannic  Acid. 

5288.  According  to  Kane,  the  coloured  precipitate  produced  in  a  decoc- 
tion of  raw  coffee,  by  subacetate  of  lead,  comprises  two  substances,  which 
may  be  extracted  by  impregnation  with  sulphydric  acid  while  suspended  in 
water,  subsequent  evaporation  of  the  filtered  liquid  to  the  consistence  of 
syrup,  and  digestion  in  strong  alcohol.     A  peculiar  kind  of  tannic  acid  dis- 
solves, called  caffee  tannic.    A  white  powder  subsides,  which,  when  heated, 
evolves  the  peculiar  smell  of  roasted  coffee.     Its  solution  in  water  reddens 
litmus.     It  is  called  caffeic  acid.     It  is  not  known  whether  the  tannic  acid 
of  tea  and  coffee  are  the  same. 

Of  Acids  modified  by  an  Union  with  Organic  Matter. 

5289.  Two  sets  of  acids  may  claim  this  description. 
Of  these,  in  one  set  the  organic  matter  to  which  the 
change  in  them  is  due,  is  an  oxidized  compound  organic 
radical,  acting  as  a  base,  capable,  under  favourable  circum- 
stances, of  being  transferred  to  other  acids.  In  the  other 
set,  the  matter  producing  the  change  does  not  contain  a 


474  ORGANIC  CHEMISTRY. 

compound  radical,  capable  by  oxidation  of  acting  as  a 
base,  and  transferrable  to  other  acids. 

Of  Acids  modified  by   Union  with  an  Oxidized  Compound 

Radical. 

5290.  Acids  of  this  set,  when  formed  of  a  monobasic 
acid,  require  for  existence  two  atoms  of  acid  and  two  atoms 
of  base.     One  of  the  acid  atoms  must  be  in  union  with  the 
oxidized  radical,  the  other  in  union  with  an  atom  of  basic 
water,  or  some  other  oxide  acting  as  a  base.     Hence,  as 
already  suggested  in  the  case  of  sulphovinic  acid  (3086), 
such  compounds  may  be  viewed  as  double  salts  of  an  oxi- 
dized radical  and  oxide  of  hydrogen,  so  that,  agreeably  to 
the  language  of  Graham,  sulphovinic  acid  is  a  sulphate  of 
ether  and  water.     But  this  does  not  explain  the  fact,  that 
a  neutral  compound  of  the  acid  and  oxidized  radical  cannot 
be  made.     Hence,  another  view,  presented  by  the  same 
author,  seems  to  be  more  satisfactory,  agreeably  to  which 
the  two  atoms  of  acid  act  as  one  bibasic  acid,*  of  course 
isomeric  with  that  of  which  it  has  been  formed.     This  ra- 
tionale seems  to  derive  strength  from  the  fact,  that  one 
atom  of  tartaric  acid  in  tartrovinic  acid,  performs  the  part 
of  two  of  sulphuric  acid  in  sulphovinic  acid,  agreeably  to 
the  usual  idea. 

5291.  In  the  other  set  of  modified  acids,  the  organic 
matter  does  not  appear  to  be  in  a  basic  state,  not  being  an 
oxide  of  a  compound  radical,  nor  capable  of  separation 
without  decomposition. 

5292.  In  three  of  the  acids  belonging  to  the  first  set 
(sulphovinic,  phosphovinic,  arseniovinic  acid),  ethyl,  being 
the  principal  radical,  is  united  to  an  inorganic  acid. 

5293.  There  are  other  instances,  as  in  that  of  sulpho- 
methylic  acid,  in  which  the  oxide  of  a  compound  radical 
plays  the  same  part  in  combination  with  a  double  atom  of 
sulphuric  acid,  that  the  oxide  of  ethyl  plays  in  the  three 
acids  above  mentioned.     Also  in  tartrovinic,  oxalovinic, 
and  camphovinic  acid,  one  atom  of  tartaric,  oxalic,  or 
camphoric  acid,  performs  the  office  of  a  double  atom  of 
sulphuric,  arsenic,  or  phosphoric  acid,  in  the  analogous 
compounds  arising  from  their  association  with  the  same 
oxidized  radical.     Other  acids  exist,  having  a  similar  con- 

*  Elements,  773. 


OF  SULPHOVINIC  ACID. 


475 


stitution  to  those  last  mentioned,  and  that  there  will  be 
many  more  produced  hereafter,  there  is  much  reason  to 
suppose. 

5294.  In  the  second  set,  there  are  several  which  are  as- 
cribed to  an  union  of  hyposulphuric  acid  with  carbon,  hy- 
drogen, and  water;  as,  for  instance, 

Isethionic  C   acid  consisting  of   }  +  C4  H4  O 

Hyposulpho-naphthalic  <    S2  O5  hyposulphu-     -  +  C20  H8 
Hyposulpho-benzoic       (  ric  acid  )  +  C14H4O3 

5295.  Other  acids  consist  of  the  elements  of  some  defi- 
nite organic  compound,  such  as  sugar  or  indigo,  so  united 
to  an  acid  as  to  form,  with  bases,  crystalline  compounds; 
which,  besides  the  peculiarity  of  their  crystalline  form, 
have  a  solubility  altogether  wanting  in  the  salts  generated, 
per  se,  by  the  acid  with  which  they  are  formed.     This  de- 
scription is  intended  for  sulpho-  saccharic  acid,  and  hypo- 
sulpho-indigotic  acid;  one  created  by  the  union  of  indigo 
with  hyposulphuric  acid,  the  other  by  the  union  of  sugar 
with  sulphuric  acid. 

5296.  Analogous  to  the  former  of  these  acids,  a  new 
acid  has  been  created,  by  the  reaction  between  sulphuric 
acid  and  acetic  acid,  of  which  the  formula,  represented 
as  C4  H4  O3  -f  S2  O5,  makes  it  a  compound  of  hyposul- 
phurous  acid;  but  Berzelius  suggests  that  the  same  ulti- 
mate elements,  in  a  different  order,  would  give  C4  H4  O2 
+  2$O3;*  and  that  the  formula  thus  made  out,  being  di- 
vided by  two,  would  give  C2  ITO  +  SO3.    This  would  make 
it  a  sulphated  oxide  of  elayl,  of  olefiant  gas  in  other  words 
(3095).t 

Of  Sulphovinic  Acid,  or  the,  Sulphate  of  Ether,  and  Water. 

5297.  Of  the  acids  above  described,  of  the  first  class,  I  shall  here  treat 
of  sulphovinic  acid  only.     While  the  limits  prescribed  to  a  text-book  do  not 
allow  me  to  do  more,  the  importance  of  this  acid,  arising  from  the  part 
which  it  performs  in  the  production  of  ethers,  and  the  expediency  of  select- 
ing it  as  an  exemplification  of  the  set  to  which  it  belongs,  renders  it  pro- 
per that  1  should  add  something  to  the  notice  already  taken  of  it  under  the 
head  of  ethyl  (3069). 

5298.  Sulphovinic  acid  is  produced  by  heating,  to  the  boiling  point  of  the 
resulting  mixture,  or  about  280°,  equal  weights  of  concentrated  sulphuric 
acid  and  alcohol  of  from  830°  to  850°;  or  by  saturating  sulphuric  acid  with 
the  vapour  of  ether,  and  adding  water  after  some  hours  have  elapsed.     In 

*  Report  on  Chemistry  for  1841. 

t  It  also  contains  the  elements  of  a  hydrated  bisulphate  of  the  oxide  of  acetyl. 
C<HsO-f  2S03+HO. 
61 


476  ORGANIC  CHEMISTRY. 

either  case,  the  resulting  liquid  is  to  be  saturated  with  oxide  of  lead,  with 
lime,  or  baryta.  From  the  resulting  sulphovinates,  the  sulphovinic  acid 
may  be  liberated  by  adding  enough  acid  to  saturate  the  inorganic  base ;  or 
in  the  case  of  that  formed  with  lead,  by  precipitating  this  metal  by  sulphy- 
dric  acid  (899). 

5299.  It  has  been  mentioned  that  sulphovinic  acid  is  equivalent  to  a  dou- 
ble sulphate  of  ether  and  water;  but  that  the  two  atoms  of  sulphuric  acid 
act  like  one  atom  of  a  peculiar  bibasic  acid,  isomeric  with  sulphuric  acid, 
since  it  cannot  be  obtained  as  a  neutral  compound,  consisting  of  one  atom 
of  oxide  of  ethyl  and  one  of  anhydrous  sulphuric  acid.     The  heavy  oil  of 
wine,  heretofore  considered  as  a  neutral  hydrated  sulphate  of  etherine,  or  of 
the  oxide  of  ethyl,  is  now  viewed  as  a  double  sulphate  of  ether  and  etherine, 
or  etherole  agreeably  to  a  new  name  employed  by  Liebig. 

5300.  Any  stronger  base  presented  to  sulphovinic  acid  takes  the  place  of 
the  water,  as  in  other  cases  where  bibasic  acids  are  in  union  with  an  atom 
of  water  and  an  atom  of  another  base;  but  the  acid  in  question  differs  from 
other  bibasic  acids  in  this,  that  the  oxidized  compound  radical  is  essential  to 
the  endurance  of  its  bibasic  property.     As  soon  as  the  oxide  of  ethyl  is  dis- 
placed, the  monobasic  character  of  the  inorganic  acid  is  resumed. 

5301.  The  salts  formed  with  sulphovinic  acid  by  the  replacement  of  the 
basic  water,  have  been  known  as  sulphovinates ;  and  so  long  as  the  nature 
of  the  acid  is  debateable,  it  will  be  preferable  to  adhere  to  this  name. 

5302.  One  of  the  most  remarkable  traits  of  the  sulphovinates,  is  that  so- 
lubility which  prevents  the  detection  of  sulphuric  acid,  even  by  solutions  of 
baryta. 

5303.  In  the  usual  process  for  producing  the  organic  oxacid  acid  ethers, 
by  their  distillation  with  alcohol  and  sulphuric  acid,  it  is  probable  that  the 
formation  of  sulphovinic  acid  is  a  preliminary  effect  (3086).    But  when  the 
mixture  is  subjected  to  heat,  the  organic  acid  and  oxide  of  ethyl,  being  com- 
petent to  form  a  volatile  compound,  go  off  in  union,  while  the  affinity  be- 
tween the  water  and  sulphuric  acid  co-operates  to  expel  them.     It  is,  there- 
fore, a  case  of  double  elective  affinity,  aided  by  the  vaporizing  influence  of 
caloric. 

5304.  It  was  upon  this  view  of  the  subject,  that  Messrs.  Boye  and  Hare 
were  enabled  to  foresee  the  production  of  the  wonderfully  explosive  perchlo- 
ric ether,  by  distilling  perchlorate  of  baryta  with  the  sulphovinate  of  the 
same  base. 

Of  Succinic  Acid. 

5305.  When  amber  is  exposed  to  heat  in  an  alembic,  succinic  acid  is 
sublimed  in  crystals,  much  contaminated  by  the  essential  oil  of  amber.    By 
digestion  in  nitric  acid,  evaporation  to  dryness,  washing  in  cold  water,  sub- 
sequent solution  in  boiling  water,  and  finally  by  crystallization,  the  acid  is 
obtained  pure.     When  combined  with  any  of  the  alkalies,  it  is  useful  in  se- 
parating the  sesquioxide  of  iron  from  the  oxide  of  manganese. 

5306.  Succinic  acid  has  a  sour  taste,  and  reddens  litmus  paper.     The 
formula  of  this  acid,  in  the  hydrated  state,  is  C4  H3  O3  +  HO,  being  from 
the  formula  monobasic.     The  formula  of  the  sublimed  acid  is  C4  H3  O3. 

Of  Benzole  Acid,  C14  H5  O3  +  HO. 

5307.  From  the  formula  it  must  be  evident  that  this  is  a  monobasic  acid, 
containing  one  atom  of  oxygen  more  than  the  compound  radical,  benzule, 
C14  H5  O3  (3052):  also,  that  replacing  an  atom  of  oxygen  by  one  of  hy- 


OF  HIPPURIC  ACID.  477 

drogen,  must  convert  it  into  the  hydruret  of  that  radical,  C1*  H5  O3  -f-  H 
(5120).     The  symbol  of  this  acid  is  Bz. 

5308.  Benzoic  acid  exists  ready  formed  in  the  resinous  product  of  vege- 
tation improperly  called  gum  benzoin,  from  which  it  may  be  extricated  by 
the  following  process : — Spread  a  pound  of  the  benzoin  over  the  bottom  of  a 
cast  iron  pot,  of  eight  or  nine  inches  in  diameter  and  of  about  two  inches  in 
depth,  the  mouth  of  the  pot  being  covered  by  filtering  paper  secured  to  the 
brim  by  paste.     Thus  covered,  the  pot  is  to  have  a  canopy  of  coarse  pack- 
ing paper  fitted  to  it,  like  a  cap,  and  secured  by  a  bandage  of  wire.     The 
pot,  thus  charged  and  prepared,  is  to  be  subjected  to  a  sand  bath  for  three 
or  four  hours.    Under  these  circumstances,  the  cavity,  included  between  the 
cover  and  cap,  becomes  studded  with  crystals  of  benzoic  acid,  quite  free 
from  the  black  empyreumatic  oil  with  which  they  are  liable  to  be  soiled, 
when  sublimed  without  the  interposition  of  the  paper.     The  acid  thus  extri- 
cated, amounts  usually  to  about  four  per  cent,  of  the  gum  employed. 

5309.  Benzoic  acid  may  likewise  be  obtained  by  boiling,  in  four  parts  of 
water,  equal  parts  of  gum  benzoin  and  hydrate  of  lime,  until  the  liquid  is 
reduced  to  ^th  of  the  original  volume.     It  is  in  the  next  place  to  be  filtered, 
and  an  addition  made  of  chlorohydric  acid.     After  a  second  filtration,  the 
acid  separates  in  crystals. 

5310.  It  is  presumed  that  benzoic  acid  exists  in  the  gum  ready  formed, 
and  is  therefore  liable  either  to  be  sublimed  by  heat,  or  removed  by  its 
affinity  for  lime,  from  which  it  is  expelled  by  the  chlorine  of  the  chlorohy- 
dric acid.* 

5311.  Properties  of  Benzoic  Acid. — It  crystallizes  in  hexagonal  needles, 
or  flexible  lamina?,  white,  pearly  and  translucent.     When  pure  it  is  inodo- 
rous, though  by  being  heated,  it  acquires  a  smell  analogous  to  that  of  ben- 
zoin.   Although  sweet  and  stimulating  to  the  taste,  it  irritates  the  palate  when 
swallowed.     It  reddens  litmus  feebly,  melts  at  248°,  and  sublimes  at  293°, 
phosphorescing  in  the  dark.     It  boils  at  492.2.     Heated  in  the  air  it  yields 
a  very  acrid  white  vapour,  which  excites  coughing.     It  is  highly  inflamma- 
ble, burning  with  a  very  smoky  flame,  leaving  no  residue.     It  is  soluble 
in  100  parts  of  cold  water,  and  in  25  at  the  temperature  of  ebullition;  va- 
porizing with  its  aqueous  solvent  when  this  is  distilled  from  it.    For  solution 
one  part  requires  two  parts  either  of  ether  or  alcohol. 

5312.  Peroxide  of  iron  precipitates  in  the  form  of  an  insoluble  subben- 
zoate,  of  a  reddish  white  or  buff  colour,  when  a  soluble  benzoate  is  added 
to  a  solution  of  peroxide  of  iron,  previously  neutralized  by  ammonia  with- 
out any  consequent  precipitation.     Hence  benzoate  of  ammonia  serves  to 
separate  the  sesquioxide  of  iron  from  the  oxides  of  manganese,  nickel,  or 
zinc;  when  the  solution  contains  neither  alumina,  yttria,  zirconia,  nor  glu- 
cina;  of  either  of  which  the  oxides  would  be  simultaneously  precipitated  if 
present.     Graham,  851. 

OfHippuric  Acid,     C13  H8  N3  O5  -f-  HO. 

5313.  Hippuric  acid  is  found  in  the  urine  of  herbiverous  mammalia. 
Liebig  supposes  that  it  is  probably  derived  from  food,  in  which  it  pre-exists ; 

*  M.  Jahn  has  remarked  that  when  the  sawdust  of  guiacum  wood  (lignum  vitas)  is 
treated  with  a  solution  of  carbonate  of  soda,  sulphuric  acid  added,  the  liquid  and  the 
resin  which  precipitates  is  washed,  dried,  and  subjected  to  heat  in  an  appropriate  ap- 
paratus, a  small  quantity  of  sublimed  benzoic  acid  is  obtained.  Berzelius'  Report, 
1341,  106.  This  justifies  an  inference  made  by  Guibourt,  that  the  crystalline  parti- 
cles observable  in  the  bark  of  the  wood  in  question,  might  be  benzoic  acid. 


478  ORGANIC  CHEMISTRY. 

since  it  abounds  in  the  urine  of  horses  fed  with  fresh  vegetables,  but  in  that 
of  the  same  animals  fed  with  hay,  or  other  dried  vegetable  matter,  is  re- 
placed by  benzoic  acid. 

5314.  The  preparation  of  hippuric  acid  is  effected  by  evaporating  the 
fresh  urine  of  the  horse  or  cow,  at  a  temperature  carefully  kept  below  that 
of  ebullition,  adding  sufficient  chlorohydric  acid  to  render  it  perceptibly 
acid,  and  subsequently  allowing  it  repose.     By  these  means,  impure  dis- 
coloured hippuric  acid  separates  in  crystals.     It  may  be  purified  by  im- 
pregnation with  chlorine,  or  by  the  addition  of  chlorohydric  acid  and  bleach- 
ing salt,  until  the  smell  and  discoloration  are  removed. 

5315.  Hippuric  acid  reddens  litmus,  crystallizes  in  large  four-sided  trans- 
parent prisms,  susceptible  of  fusion,  without  loss  of  weight,  into  an  oleagi- 
nous liquid  which  yields  crystals  on  cooling.     At  temperatures  higher  than 
its  point  of  fusion,  it  may  be  decomposed  into  benzoic  acid  and  benzoate 
of  ammonia,  which  may  be  distilled  and  condensed  in  red  drops,  associated 
with  an  oily  product  having  an  agreeable  odour  resembling  that  of  the 
tonka  bean.     Towards  the  end  of  the  distillation,  cyanhydric  acid  comes 
over,  leaving  a  porous  residue  of  carbon,    Hippuric  acid  requires  400  parts 
of  cold  water  for  its  solution,  but  is  very  soluble  in  hot  water,  and  still  more 
so  in  alcohol.     In  ether  it  is  but  slightly  soluble.     Concentrated  sulphuric 
acid  dissolves  hippuric  acid  without  discoloration  ;  but  at  a  higher  tempe- 
rature the  solution  blackens,  evolving  sulphurous  acid,  and  a  sublimate  of 
benzoic  acid.   By  nitric  acid  it  is  transformed  into  benzoic  acid.    In  chloro- 
hydric acid  it  dissolves  without  alteration.     Peroxide  of  manganese  and 
sulphuric  acid,  aided  by  heat,  convert  it  into  carbonic  acid,  ammonia,  and 
benzoic  acid.    Boiled  in  water  with  the  puce  oxide  of  lead,  it  is  transformed 
into  the  amiduret  of  benzule,  or  benzamide  and  carbonic  acid.     Distilled 
with  four  times  its  weight  of  slaked  lime,  this  acid  is  converted  into  ammo- 
nia and  a  volatile  oil  called  benzole,  with  a  greyish  residuum. 

5316.  When  the  urine  of  the  horse  is  left  to  itself  for  a  long  while,  or 
exposed  to  a  rapid  evaporation,  only  benzoic  acid  is  found  therein.     It  is  in 
combination  with  ammonia  or  soda  that  this  acid  exists  in  urine. 

5317.  Of  the  Hippurates. — The  combinations  of  hippuric  acid  with  the 
oxides  of  metals  proper,  excepting  iron,  being  more  soluble  in  water  when 
boiling  than  when  cold,  may  be  obtained  in  crystals,  from  an  aqueous  so- 
lution made  at  the  temperature  of  ebullition,  and  subsequently  cooled.     By 
reaction  with  the  hydrates  of  potash  or  lime,  the  hypurates  yield  ammonia, 
and  an  oily  liquid,  probably  benzole. 

5318.  Of  Formobenzulic  Acid,  Bz  H8  2HO3  +  HO.— This  acid  con- 
sists of  formic  acid  and  the  hydruret  of  benzule,  being  created  during  the 
reaction  of  chlorohydric  acid  with  the  distilled  water  of  bitter  almonds, 
comprising,  of  course,  the  hydruret  and  cyanhydric  acid  (3055).     The 
cyanhydric  acid  is  decomposed  into  ammonia  and  formic  acid.     With  this 
acid,  while  nascent,  the  hydruret  combines. 

5319.  Formobenzulic  acid,  thus  obtained,  is  in  the  state  of  pulverulent 
white  crystals,  fusible  into  an  oily  liquid  at  the  expense  of  the  water  of  crys- 
tallization, and  capable,  when  aided  by  heat,  of  decomposing  the  acetates, 
carbonates,  and  benzoates.     Its  aqueous  solution,  when  submitted  to  chlo- 
rine, to  nitric  acid,  or  to  peroxide  of  manganese  with  diluted  sulphuric  acid, 
is  resolved  into  carbonic  acid,  and  the  hydruret  which  forms  its  charac- 
teristic ingredient.     It  has  the  same  capacity  of  saturation  as  formic  acid. 
Of  course  it  is  a  monobasic  acid. 


OF  SALICULOUS  ACID.  479 

OF  THE  ACID  OILS  OF  SPIREA  ULMARIA  AND  GAULTHERIA. 

5320.  As  the  results  obtained  by  Mr.  Procter,  Jr.,  respecting  the  analogy 
or  identity  of  the  oils  of  gaultheria  and  spirea  ulmaria,  must  create  a  desire 
to  be  acquainted  with  both,  I  have  abstracted,  with  some  changes  in  the 
style,  from  Gregory's  translation  of  Liebig,  so  much  as  relates  to  saliculous 
acid,  and  have  subjoined  some  quotations  from  Procter's  memoir.     I  have 
not  thought  it  necessary  to  alter  the  names  employed  by  Gregory.     Yet 
salicyl  might  be  considered  as  a  compound  halogen  body,  combining  with 
hydrogen,  like  cyanogen  in  cyanhydric  acid,  in  which  case,  consistently, 
its  name  would  be  salicohydric  acid.     Of  course  this  acid,  in  combining 
with  oxybases,  would  have  to  be  considered  as  generating  salicides  of  their 
radicals  respectively.     Were  this  mode  of  contemplating  the  subject  admis- 
sible, the  atom  of  hydrogen  which  forms  the  radical  in  salicohydric  acid, 
must  be  supposed  to  be  converted  into  water  by  uniting  with  an  equivalent 
of  oxygen  from  the  oxybase  of  any  radical  with  which  it  may  combine.     It 
must,  however,  be  evident,  that  the  adoption  of  these  innovations  in  nomen- 
clature would  be  attended  by  great  practical  inconvenience  from  the  conse- 
quent multiplication  of  discordant  names.     And  were  it  otherwise,  I  should 
not  deem  it  judicious  to  make  the  suggested  changes,  because  our  know- 
ledge of  such  compound  radicals  as  salicyl,  and  of  the  state  in  which  they 
exist  in  their  alleged  combinations,  is  altogether  hypothetical  and  insuscep- 
tible of  any  conclusive  proof.    Salicylous  acid  may  be  viewed  as  a  hydrated 
oxacid,  C14  H5  O3  +  HO  (3063,  5343). 

Of  Salicylous  or  Saliculous  Acid,  also  called  the  Hydruret  of  Salicyl, 
but  more  properly  considered  as  Salicohydric  Acid,  C14  H5  O4  -f-  H. 

5321.  This  acid  was  first  discovered  by  Pagenstecher  in  the  volatile  oil 
of  spiraea  ulmaria;  by  Piria  as  a  product  of  the  decomposition  of  salicine, 
who  ascertained  its  nature  and  composition. 

5322.  To  obtain  it,  the  oil  of  spiraea  is  distilled  with  an  aqueous  solution 
of  potash  in  excess  as  long  as  any  oil  distils.     The  residue,  a  solution  of 
saliculite  of  potash,  is  supersaturated  with  dilute  sulphuric  acid,  and  again 
distilled,  when  saliculous  acid  comes  over  with  the  vapour  of  water.     Or, 
according  to  Piria,  a  mixture  of  one  part  of  salicine,  one  part  bichromate  of 
potash,  two  and  a  half  of  oil  of  vitriol,  and  twenty  of  water,  is  to  be  subjected 
to  distillation.     The  salicine  being  dissolved  in  part  of  the  water,  and  the 
acid  diluted  with  the  rest,  the  whole  materials  are  mixed  in  a  retort,  when 
heat  is  excited  with  a  gentle  effervescence.     When  this  ceases,  the  distilla- 
tion should   be  commenced.     Half  a  pound  of  salicine  yields  about  two 
ounces  of  saliculous  acid.     In  both  processes  the  distilled  liquid  contains 
saliculous  acid,  which  separates  from  the  water.     It  is  purified  by  washing 
with  water  and  rectification  with  chloride  of  calcium. 

5323.  It  is  a  colourless  or  pale  yellow,  oily,  inflammable  liquid;  sp.  gr. 
1.1731,  which  boils  at  370°,  or,  according  to  Piria,  at  380°,  and  congeals 
at  —  4°.     It  has  a  burning  taste,  and  a  pleasant  aromatic  odour;  is  some- 
what soluble  in  water,  and  mixes,  in  all  proportions,  with  alcohol  and  ether. 
Its  solution  first  reddens,  then  bleaches  litmus.     It  is  decomposed  by  con- 
centrated sulphuric  acid.     When  placed  in  contact  with  chlorine  or  bro- 
mine, one  eq.  hydrogen  is  removed,  which,  with  those  elements  severally, 
forms  chlorohydric  or  bromohydric  acids;  and  is  replaced  by  one  eq.  chlo- 
rine or  bromine,  producing  chlorosaliculic,  or  bromosaliculic  acid.     Salicu- 
lous acid,  treated  with  an  excess  of  hydrate  of  potash,  evolves  hydrogen 


480  ORGANIC  CHEMISTRY. 

gas,  while  saliculic  acid  is  formed.  Saliculous  acid  likewise  disengages  hy- 
drogen by  reaction  with  potassium,  forming  saliculite  of  potash. 

5324.  Saliculous  Acid  with  Bases. — Saliculous  acid  combines  with  me- 
tallic oxides,  its  basic  water  being  replaced  by  one  eq.  metallic  oxide.    The 
resulting  fixed  alkaline  and  ammoniacal  saliculites  are  soluble,  and  capable 
of  an  alkaline  reaction.     The  rest  are  insoluble.     Most  of  them  are  yel- 
low, and  contain  water  of  crystallization.     A  solution  of  the  acid  colours 
the  salts  of  peroxide  of  iron  of  an  evanescent  purple  colour.     In  acetate  of 
copper  it  produces  a  green  precipitate.     Saliculous  acid  is  separated  from 
the  saliculites  by  the  stronger  acids. 

5325.  Saliculite  of  Ammonia,  or  salicide  of  ammonium,  a  solid  yellow 
mass,  is  prepared  by  adding  concentrated  liquid  ammonia  to  saliculous  acid. 
It  is  without  taste,  having  a  faint  odour  of  roses;  sparingly  soluble  with- 
out change  of  colour,  in  cold  water  and  alcohol;  more  readily  dissolved  by 
hot  alcohol.    By  the  cooling  of  a  saturated  solution,  transparent  pale  yellow 
needles  are  obtained.     It  is  spontaneously  decomposed  if  kept  moist;  be- 
coming black,  semi-fluid,  and  exhaling  ammonia  with  a  penetrating  smell  of 
roses.     Dry  saliculous  acid  readily  absorbs  dry  ammonia;  and  the  com- 
pound, according  to  Ettling,  contains  three  atoms  of  the  acid  and  two  atoms 
of  ammonia. 

5326.  Saliculamide. — If  one  measure  of  saliculous  acid  be  dissolved  in 
three  of  alcohol,  and  ammonia  added  by  successive  drops,  the  liquid  con- 
cretes into  a  solid  mass  of  fine  yellow  needles.    With  the  aid  of  a  moderate 
heat  these  crystals  dissolve;  and  the  solution,  by  repose,  deposits  golden- 
yellow,  brilliant,  transparent  prisms,  which,  when  dry,  are  hard  and  pul- 
verizable.     Here  three  atoms  of  the  acid  (or  one  atom  considered  as  a  tri- 
basic  acid)  are  acted  on  by  two  of  ammonia,  six  atoms  of  water  being  elimi- 
nated.    The  alcoholic  liquid  in  which  these  crystals  have  been  formed,  is 
no  longer  able,  even  at  a  boiling  heat,  to  dissolve  them.    They  now  require 
a  threefold  quantity  of  alcohol.     This  would  indicate,  that  at  first  saliculite 
of  ammonia  is  formed,  which,  by  a  longer  contact  with  ammonia,  and  a 
slow  separation  of  the  crystals,  passes  into  saliculamide.     This  body  is  de- 
composed by  a  high  temperature.     Heated  with  acids  and  alkalies,  it  is  re- 
soived  into  saliculous  acid  and  ammonia.     It  is  insoluble  in  water.     For- 
mula, C43  H18  O6  N3. 

5327.  Saliculite  of  Potash  ;  Neutral. — This  is  best  obtained  by  adding 
saliculous  acid  to  a  warm  solution  of  potash  in  alcohol,  and  allowing  the 
whole  to  cool,  when  the  salt  separates  almost  pure  in  the  form  of  four-sided 
pearly  tables,  nearly  colourless,  very  soluble  in  water,  spontaneously  decom- 
posed by  exposure  to  the  air  in  a  moist  state.    It  contains  water  of  crystalli- 
zation, which  is  expelled  by  a  heat  of  212°.    Formula,  2(C14  H5  O3)+^Q  £ 

If  the  neutral  salt  be  dissolved  in  hot  alcohol,  and  saliculous  acid  added,  an 
acid  salt  is  deposited,  on  cooling,  in  yellowish-white,  long;  fine,  and  brilliant 
needles.  When  dry  it  becomes  yellow  at  a  temperature  of  230°.  Water 
decomposes  it  into  a  neutral  salt,  and  saliculous  acid,  which  separates. 

5328.  Saliculites  of  Soda,  Lime,  Baryta,  and  Magnesia,  may  be 
formed  directly.     They  have  the  properties  of  the  potash  salt.     The  salt  of 
soda  contains  two  atoms  of  water  of  crystallization,  removable  by  a  heat  of 
230°.     There  is  likewise  an  acid  salt  of  soda  in  fine  shining  needles.     Sa- 
liculite of  copper  is  anhydrous  and  green.     The  salts  of  zinc  and  mercury 
are  yellow  and  insoluble. 

5329.  Basic  Saliculite  of  Lead. — Saliculous  acid  being  dissolved  in 
dilute  alcohol,  and  acetate  of  lead  added  to  the  boiling  solution,  on  cooling 


OF  SALICULOUS  ACID.  481 

the  salt  is  deposited,  and  may  be  separated  by  boiling  alcohol  from  any  ad- 
hering acid.  It  is  a  lemon-yellow  powder,  which,  when  heated,  froths  up, 
giving  off  water  and  acid  ;  insoluble  in  water.  Its  formula  is  Ct4  H5  O3  -f- 
2PbO.  If  saliculous  acid  be  added  to  diacetate  of  lead,  a  yellow  powder  of 
the  same  composition  is  precipitated. 

5330.  Saliculite  of  Silver. — A  solution  of  nitrate  of  silver  causes,  with 
oneof  saliculite  of  potash,  a  greenish-yellow  precipitate,  which,  when  heated, 
is  reduced  without  disengagement  of  gas,  the  vessel  being  silvered  by  the 
reduced  metal. 

5331.  Melanic  Acid,  C10  H4  O5. — Discovered  by  Piria.     When  salicu- 
lite of  potash  is  exposed  to  the  air,  it  acquires  a  green  colour,  which,  after 
some  time,  becomes  black.     When  no  further  change  is  perceived,  the  sa- 
liculous acid  is  completely  converted  into  acetic  acid  and  a  black  powder. 
The  acetic  acid  thus  formed  is  in  the  exact  proportion  to  combine  with  all 
the  potash  contained  in  the  original  salt.     The  black  powder  possesses  acid 
properties,  and  unites  with  bases ;  from  which  circumstance  it  has  received 
its  name. 

5332.  Three  equivalents  of  oxygen  and  two  of  water  unite  with  one  atom 
of  saliculite  of  potash,  and  convert  its  acid  into  one  equivalent  of  acetic, 
and  one  equivalent  of  melanic  acid. 

5333.  Saliculic  Acid,  C14  H5  O5  +  HO.— Discovered  by  Piria.     This 
acid  is  generated  by  heating  saliculous  acid  with  caustic  potash.    The  mix- 
ture at  first  assumes  a  brown  colour,  but  the  heat  must  be  continued  until  it 
is  entirely  white.     At  this  time  hydrogen  is  disengaged.     The  residue  is  to 
be  dissolved  in  water  and  treated  with  a  mineral  acid,  which  separates  the 
saliculic  acid.     In  order  to  obtain  it  pure  it  must  be  repeatedly  crystallized. 
Saliculic  acid  is  likewise  formed,  when  coumarin  (stearopten  of  the  Tonka 
bean)  is  treated  with  potash  in  a  similar  manner. 

5334.  Saliculic  acid  sublimes  without  decomposition,  and  may  be  thus 
obtained  in  the  form  of  long  crystalline  needles,  very  similar  in  their  ap- 
pearance to  benzoic  acid.     It  crystallizes  from  water  in  fine  tufts.     This 
acid  dissolves  with  difficulty  in  cold  water,  but  very  easily  both  in  hot 
water  and  in  alcohol.     Sulphuric  acid  decomposes  it  when  they  are  heated 
together. 

5335.  The  salts  of  this  acid  have  been  little  examined.     The  saliculate 
of  silver  is  insoluble  in  water. 

5336.  Chlorosaliculic  Acid,  also  called  chloride  of  salicyl,  chloride  of 
spiroyle.     Dry  chlorine  gas  is  passed  through  anhydrous  saliculous  acid  as 
long  as  chlorohydric  acid  is  disengaged.     On  cooling,  the  compound  be- 
comes solid  and  crystalline.     It  may  be  purified  by  crystallization  from  a 
hot  alcoholic  solution,  which  deposits  it,  on  cooling,  in  the  form  of  pale  yel- 
low, oblique,  rhombic  tables,  of  a  pearly  lustre,  having  a  peculiar  aromatic 
odour,  and  the  capability  of  being  sublimed  without  alteration.    It  is  inflam- 
mable, burns  with  a  green  flame,  is  insoluble  in  water,  but  soluble  in  alco- 
hol and  ether.     It  combines  with  alkalies,  and  may  be  separated  from  them 
unchanged  by  acids.     An  alcoholic  solution  gives  with  acetate  of  copper  a 
greenish-yellow,  and  with  acetate  of  lead  a  yellow  precipitate.     Persalts  of 
iron  are  tinged  by  it  of  a  dark  blue.     When  heated  with  potassium,  it  is 
decomposed  with  heat  and  light.     Ammoniacal  gas  converts  it  into  chloro- 
saliculimide. 

5337.  This  chloracid  is  distinguished  from  all  analogous  compounds  of 
chlorine  with  compound  radicals^  by  its  power  of  combining  with  bases,  and 
of  resisting  the  action  of  those  bodies.     It  forms  with  metallic  oxides  pecu- 


482  ORGANIC  CHEMISTRY. 

liar  salts,  in  which  one  atom  of  chtorosaliculic  acid  is  combined  with  one 
atom  of  metallic  oxide,  supposing  the  oxygen  and  chlorine  to  change  places; 
so  that  they  may  be  considered  as  compounds  of  salicuiic  acid  with  metallic 
chlorides,  C14  H5  O5  +  MCI,  like  the  compounds  of  the  chlorochromic  acid 
with  alkalies  or  metallic  chlorides.  Formula  of  chlorosaliculic  acid,  C14 
H5  O4  Cl. 

5338.  Chlorosaliculimide. — Formed  by  the  action  of  ammonia  on  the 
preceding  compound.     Dry  ammonia  is  passed  over  chlorosaliculic  acid  in 
a  proper  apparatus  as  long  as  water  is  formed.     The  new  substance  is  left 
behind  in  a  state  of  purity.     It  forms  a  solid  deep  yellow  mass,  insoluble  in 
cold  water,  decomposed  by  hot  water,  acids,  and  alkalies,  with  the  forma- 
tion of  ammonia  and  chlorosaliculic  acid.     Three  atoms  of  chlorosaliculic 
acid  with  two  of  ammonia,  produce  six  atoms  of  water  and  one  atom  of 
Chlorosaliculimide,  C43  H15  O12  Cl3  +  Na  H6  =  C43  H15  Cl3  N3  O6  +  6HO. 

5339.  It  hence  appears  to  be  saliculimide,  in  which  three  atoms  of  hy- 
drogen are  replaced  by  three  atoms  of  chlorine. 

5340.  Bromosaliculic  Acid. — This  compound,  in  its  preparation,  pro- 
perties, and  action  with  ammonia,  is  completely  analogous  to  the  pre- 
ceding. 

5341.  lodosaliculic  Acid. — Saliculous  acid  dissolves  iodine  in  great 
quantity,  without  apparent  decomposition.     But  iodosaliculic  acid  may  be 
obtained  by  distilling  iodide  of  potassium  with  chlorosaliculic  acid.     It  su- 
blimes in  the  form  of  a  dark-brown  fusible  mass,  analogous  in  its  relations 
to  the  two  preceding  compounds. 

5342.  Nitrosaliculic  Acid,  C12  H3  N4  O13. — Saliculous  acid,  warmed 
with  moderately  strong  nitric  acid,  is  converted,  with  disengagement  of  ni- 
trous acid,  into  a  crystalline  mass  of  nitrosaliculic  acid,  which  is  purified 
by  washing  with  water,  solution  in  alcohol,  and  crystallization.     By  spon- 
taneous evaporation,  the  alcoholic  solution  yields  small  transparent  prisms 
of  a  golden-yellow  colour,  sparingly  soluble  in  water.     The  solution  stains 
the  skin  and  nails  permanently  yellow,  precipitates  the  salts  of  lead  yellow, 
and  those  of  copper  green.     It  is  inodorous,  but  has  an  acrid  taste,  exciting 
cough.     Heated  with  potassium,  it  is  decomposed  with  explosive  ignition. 
It  combines  with  alkalies  to  form  crystallizable  compounds,  which  detonate 
when  dried  and  heated.     Ammonia  colours  the  acid   a  deep  blood-red. 
Chloride  of  iron  is  coloured  cherry-red  by  it.     These  compounds  demand  a 
more  accurate  study. 

5343.  Fuming  nitric  acid  acts  violently  on  saliculous  acid,  producing  a 
volatile  yellow  matter,  and  a  fixed  residue  containing  a  crystallizable  sub- 
stance not  yet  examined. — Gregory's  Translation  from  Liebig. 

Of  the  Acids  from  the  Oil  of  Gaultheria.* 

5344.  From  the  observations  and  experiments  of  Mr. 
Procter,  Jr.,  published  in  the  American  Journal  of  Phar- 

*  "Oil  of  Gaultheria  Procumbens. — This  volatile  oil  is  extensively  used  by  the 
pharmaceutists  of  this  country  to  flavour  syrups,  etc.  Most  of  the  oil  used  in  this 
city  is  obtained  from  distillers  residing  in  New  Jersey,  in  which  State  the  plant 
yielding  it  grows  in  great  abundance.  As  usually  found  in  the  shops,  it  has  a  more 
or  less  intense  red  colour;  but  when  recently  distilled  it  is  colourless,  or  nearly  so. 
Its  density,  as  the  result  of  several  careful  observations,  is  1.173,  and  its  boiling  point 
412°,  Fahr.;  the  mercury  remaining  stationary  at  that  point.  Its  taste  is  burning 
and  aromatic;  it  is  slightly  soluble  in  water,  to  which  it  communicates  its  odour  and 
taste;  and  it  mixes  with  alcohol  and  ether  in  all  proportions."— Procter,  page  212. 


OF  THE  OIL  OF  GAULTHERIA.  483 

macy  for  October  last  (1842),  it  appears  that  there  is  a 
great  resemblance  between  the  habitudes  of  oil  of  gaul- 
theria,  and  that  from  spiraea  ulmaria,  described  above  as 
saliculous  acid.  It  appears  either  that  salycyl  exists  in 
the  oil  of  gaultheria,  and  is  productive  of  compounds  re- 
sembling those  produced  by  like  reactions  with  the  oil  of 
spirea  ulmaria;  or  that  another  compound  radical  exists 
in  the  oil  of  gaultheria,  which  has  a  close  analogy  in  pro- 
perties to  salycyl. 

5345.  I  will  here  quote  the  account  given  by  Mr.  Proc- 
ter, Jr.,  in  which  the  habitudes  of  the  two  oils  in  question 
are  contrasted. 

5346.  Mr.   Procter  premises  in  the  following  words: — "For  several 
years  past  it  has  been  supposed*  that  the  volatile  oil  of  the  gaultheria  pro- 
cumbens,  either  from  the  analogy  of  their  odour  or  specific  gravity,  pos- 
sessed similar  properties  with  the  oil  of  spirsea  ulmaria,  without  any  steps 
having  been  taken  to  ascertain  the  correctness  of  the  supposition.     The  ob- 
servations which  follow  are  intended  to  throw  light  on  this  subject.     The 
chemical  characteristics  of  oil  of  gaultheria  have  been  found,  in  many  in- 
stances, to  accord  with  those  described  as  peculiar  to  saliculous  acid,  yet 
several  instances  occur  to  the  contrary. 

5347.  "  They  have  the  same  density,  and  the  aqueous  solution  of  each 
colours  the  persalts  of  iron  purple.     The  compounds  which  potassa,  soda, 
and  oxide  of  copper  form  with  oil  of  gaultheria,  are  very  like  the  salts  of 
saliculous  acid  with  those  bases. 

5348.  "  The  action  of  an  excess  of  caustic  potassa  with  heat  produces  a 
crystalline  body,  identical  in  all  its  reactions  with  saliculic  acid,  as  described 
by  Piria. 

5349.  "  The  compound  of  oil  of  gaultheria  and  potassa,  when  exposed  to 
the  combined  influence  of  moisture  and  the  atmosphere,  undergoes  a  decom- 
position similar  to  that  of  saliculite  of  potassa. 

5350.  "The  reactions  of  chlorine  and  bromine  with  oil  of  gaultheria 
yield  compounds  similar  to  those  with  saliculous  acid;  and  nitric  acid  also 
produces  results  of  an  analogous  character. 

5351.  "On  the  contrary,  the  boiling  point  of  oil  of  gaultheria  is  many 
degrees  higher  than  that  of  saliculous  acid.     Ammonia  forms  a  compound 
with  it  which  differs  from  saliculite  of  ammonia  in  not  being  decomposed  by 
acids  with  the  separation  of  the  oil,  nor  by  potassa  with  the  separation  of 
ammonia.    All  endeavours  to  form  the  body  called  salicvlimide  by  Liebig, 
with  the  process  he  gives,  were  ineffectual.     The  compounds  of  baryta  and 
lead  with  oil  of  gaultheria  are  white,  while  the  saliculites  of  those  bases  are 
yellow.     But  the  most  striking  difference  between  these  substances  is,  that 
when  oil  of  gaultheria  is  boiled  with  solution  of  potassa,  it  is  not  recovera- 
ble by  means  of  an  acid,  as  saliculous  acid  is.     Under  these  circumstances 
a  crystalline  substance  is  precipitated,  which  is  the  same  acid  that  results 
from  heating  the  oil  with  an  excess  of  potassa." 

*  Dr.  Wood,  U.  S.  Dispensatory. 
62 


484  ORGANIC  CHEMISTRY. 

5352.  "  Dropped  into  a  concentrated  solution  of  potassa  or  soda,  the  oil 
is  instantly  solidified,  becomes  white,  and  separates  from  the  alkaline  solu- 
tion while  heat  is  disengaged. 

5353.  "  Oil  of  gaultheria  decomposes  the  carbonates  of  potassa  and  soda 
gradually,  without  heat;  but  if  gently  warmed,  the  evolution  of  carbonic 
acid  is  evident. 

5354.  "Chlorine  and  bromine,  when  brought  into  contact  with  oil  of 
gaultheria,  combine  with  it;  the  mixture  becomes  very  hot,  and  hydrochlo- 
ric and  hydrobromic  acids  are  evolved.     Iodine  is  dissolved  by  the  oil, 
forming  a  deep  red  solution  without  combining  with  it,  as  heat  dissipates 
the  iodine  without  the  production  of  any  hydriodic  acid. 

5355.  "Nitric  acid  of  density  1.40,  assisted  by  heat,  converts  oil  of  gaul- 
theria into  a  crystalline  substance  having  acid  properties,  whilst  nitrous  acid 
fumes  are  evolved.     If  fuming  nitric  acid  be  employed,  the  reaction  is  vio- 
lent, without  the  assistance  of  heat,  and  a  different  product  is  obtained. 

5356.  "When  oil  of  gaultheria  is  added  to  concentrated  sulphuric  acid, 
the  latter  becomes  slightly  coloured,  and,  if  heated,  the  odour  of  the  oil  is 
destroyed. 

5357.  "When  oil  of  gaultheria  is  distilled  with  solution  of  potassa  in  ex- 
cess, the  distilled  liquid  has  neither  the  odour  nor  taste  of  the  oil,  and  con- 
sequently its  constitution  differs  from  that  of  the  oil  of  spiraea  ulmaria,  which, 
under  the  same  circumstances,  yields  a  volatile  oil  distinct  from  saliculous 
acid,  that  acid  remaining  combined  with  the  potassa." 

5358.  For  further  particulars  respecting  the  results  of 
Mr.  Procter's  meritorious  investigation,  I  refer  to  his  me- 
moir.   I  hope  that  the  brilliant  success  which  has  attended 
his  efforts,  may  cause  them  to  be  emulated  by  many  of  his 
countrymen. 

OF  URIL, 
Or  Cyanoxalic  Acid. 

5359.  The  preceding  appellations  have  been  given  to  a  hypothetical  com- 
bination of  carbon,  nitrogen,  and  oxygen,  of  which  the  formula  is  C8  N3  O*, 
and  which  may  be  considered  either  as  a  compound  of  carbonic  acid  and 
cyanogen,  or  as  resulting  from  the  substitution  of  cyanogen  for  one  of  the 
three  atoms  of  oxygen  in  oxalic  acid.     Thus  the  formula  of  the  latter  being 
Ca  O3,  that  of  uril  will  be  C3  O3-j-Cy.     It  may  be  remembered  that  urea,  a 
erystallizable  matter  of  the  urine,  has  been  mentioned  as  being  equivalent  to 
cyanate  of  ammonia,  C3  NO  -f-  NH4O,  or  more  properly  a  cyanate  of  the 
oxide  of  ammonium,  this  oxide  comprising  the  elements  of  one  atom  of  am- 
monia, NH3,  and  one  of  water,  HO  (1307). 

5360.  This  being  premised,  the  following  formula?  of  the  combinations  of 
uril  will,  it  is  presumed,  be  understood. 

(  1  urea  =  1  uric  acid,  C10  N4  H*  O6 

9  ptm,       r'l  j.     J  °3  +  4HO  =  all°xan>  C8  N3  H4  °10 

\  O  +  5HO  =  alloxantine,  C"  N3  H*  O" 
1 1  ammonia  +  2HO  =  uramile  C8  N3  H5  O8 


OF  URIC  ACID.  485 

Of  Uric  Acid,  and  various  Substances  to  which  it  gives  rise. 
Of  Uric  Acid,  C10  H*  O8  N4. 

5361.  As  the  most  frequent  and  abundant  material  in 
urinary  calculi,  uric  acid,  and  the  substances  which  con- 
tribute to  its  formation,  or  which  may  be  derived  from  it, 
merit  the  most  sedulous  attention. 

5362.  This  acid  is  an  ingredient  in  the  urine  of  men, 
and  generally  in  that  of  carnivorous  animals,  forming,  as 
already  mentioned,  calculi,  depositions  from  urine,   and 
gouty  or  arthritic  concretions.     In  the  state  of  urate  of 
ammonia,  it  constitutes  the  greater  proportion  of  the  ex- 
crement of  the  boa  constrictor  and  other  serpents;  also  of 
birds,  more  especially  those  of  the  carnivorous  species.     I 
found  it  to  abound  in  that  of  a  young  eagle.     An  accumu- 
lation of  the  excrement  of  certain  aquatic  birds,  containing 
a  large  amount  of  this  acid,  on  some  islands  near  the  coast 
of  Peru  and  Chili,  under  the  name  of  guano,  is  much  used 
as  manure. 

5363.  I  infer  that  the  best  process  for  obtaining  uric 
acid  is  as  follows: — Boil  the  substance  from  which  it  is  to 
be  extracted  in  a  dilute  solution  of  caustic  potash.     On  al- 
lowing the  decoction  to  cool,  urate  of  potash,  which  is  al- 
most insoluble  in  cold  water,  precipitates,  leaving  some 
impurities   in   solution.     After   being   well   washed   with 
water,  the  urate  thus  separated  is  redissolved  in  a  boiling 
solution  of  potash,  next  filtered,  while  hot,  and  afterwards 
added  to  an  excess  of  chlorohydric  acid  maintained  in  a 
state  of  ebullition.     The  uric  acid  which  precipitates,  is 
to  be  rendered  pure  and  white  by  repeated  aqueous  ablu- 
tion. 

5364.  Liebig  recommends,  that  in  extracting  uric  acid 
from  excrement,  a  solution  of  borax  be  employed,  as  it 
does  not  take  up  so  large  a  portion  of  the  impurities  as 
caustic  potash. 

5365.  Uric  acid  crystallizes  in  thin  spangles,  with  a  daz- 
zling white  satin  lustre.     It  is  insipid  and  inodorous.     At 
a  boiling  heat  the  crystals  sustain  no  loss  of  water.     It  is 
heavier  than  water,  almost  insoluble  in  that  liquid  when 
cold,  and  but  little  soluble  in  it  when  hot.     The  solution 
feebly  reddens  litmus. 

5366.  When  to  a  well  refrigerated  aqueous  solution  of 


486  ORGANIC  CHEMISTRY. 

borate  of  soda,  holding  uric  acid  dissolved,  chlorohydric 
acid  is  added,  the  uric  acid  precipitates  in  a  hydrated 
state,  forming  a  transparent  jelly,  which,  by  a  feeble  heat, 
is  converted  into  a  crystalline  powder,  consisting  of  anhy- 
drous uric  acid. 

5367.  This  acid  is  soluble  in  concentrated  sulphuric 
acid,  but  separates  on  dilution  with  water.     It  is  more 
soluble  in  concentrated  chlorohydric   acid  than  in  pure 
water. 

5368.  Subjected  to  dry  distillation,  it  yields  the  same 
products  as  urea,  that  is  to  say,  cyanic  acid,  cyamelide, 
cyanhydric  acid,  a  little  carbonate  of  ammonia,  and  a 
brown  and  carbonaceous  residue  very  rich  in  nitrogen. 
During  this  decomposition,  the  hydrated  cyanic  acid  and 
ammonia  unite  in  the  neck  of  the  retort,  forming  urea. 

5369.  In  dilute  nitric  acid,  uric  acid  dissolves,  with 
lively  effervescence,  from  the  escape  of  equal  volumes  of 
carbonic  acid  and  nitrogen.     The  resulting  solution  con- 
tains alloxan,  alloxatin,  urea,  parabanic  acid,  and  ammo- 
nia. 

5370.  By  the  addition  of  an  excess  of  ammonia,  the 
concentrated  liquid  becomes  purple  red,  from  the  genera- 
tion of  murexide.     This  effect  is  one  of  the  means  of  re- 
cognising the  acid. 

5371.  Fused  with  hydrate  of  potash,  uric  acid  produces, 
with  the  alkali  or  its  metal,  a  carbonate,  a  cyanate,  and  a 
cyanide. 

5372.  Subjected  to  boiling  water  with  the  bioxide  of 
lead,  it  is  resolved  into  allantoin,  oxalic  acid,  and  urea. 
Heated  to  320°,  with  a  little  water  in  a  tube  hermetically 
sealed,  this  acid  is  dissolved,  without  the  evolution  of  gas, 
forming  a  yellow  transparent  liquid,  which,  on  lowering  the 
temperature,  assumes  a  gelatinous  appearance. 

5373.  Uric  acid  is  peculiar  in  combining  with  metallic 
oxides,  without  abandoning  water.     The  urates  of  the  al- 
kalies and  alkaline  earths  are  little  soluble  in  cold  water, 
but  very  soluble  in  this  liquid  when  boiling,  the  solubility 
being   augmented   by  an   excess  of  alkali.     The   urates 
formed  with  other  metallic  oxides  and  with  ammonia,  are 
white  and  insoluble.     All  the  urates  are  easily  decompo- 
sable by  acids,  even  by  the  acetic  acid.     When  first  libe- 
rated, uric  acid  assumes  the  form  of  a  jelly,  which  is  soon 
changed  into  fine  brilliant  spangles. 


OF  URIC  ACID.  487 

5374.  Allantoin  is  a  substance  arising  from  the  urine  of  a  fetus  in  the 
ttterus  of  a  cow,  and  may  be  obtained  from  the  waters  of  the  allantois  of 
this  animal,  by  evaporation  and  crystallization.     Jt  may  be  more  easily 
procured  by  the  following  means: — To  uric  acid,  diffused  through  twenty 
parts  of  boiling  water,  freshly  prepared,  bioxide  of  lead  is  to  be  added  as 
long  as  the  colour  is  affected.     The  boiling  liquor  is  to  be  filtered,  and  eva- 
porated until  crystallization  commences.     It  is  then  allowed  to  cool  in  a 
quiescent  state.     By  this  procedure  the  allantoin  separates  in  crystals,  an 
oxalate  of  the  protoxide  of  lead  being  simultaneously  produced. 

5375.  In  order  to  understand  this  process,  the  composition  of  the  mate- 
rials and  products  should  be  remembered.     They  are  as  follows: — Uric 
acid,  C10  H4  N4O8;  bioxide  of  lead,  one  atom  of  protoxide,  one  of  oxygen; 
urea,  C2  N3  H*  O3;  allantoin,  C4  N4  H5  O5;  oxalic  acid,  C3  O3. 

5376.  Hence,  assuming  that  five  atoms  of  water  are  taken  up,  and  one 
atom  of  oxygen  for, each  of  the  four  atoms  of  bioxide  of  lead,  the  materials 
are: — 

Two  atoms  of  uric  acid,     -         -         -         C30  H  8  N8  Oia 
Five  water,      -  H 5         O 5 

Four  oxygen,  -  O  * 


C20  H13  N8  O31 

The  products  are  two  urea,  C  *  H  8  N4  O  * 

Four  oxalic  acid  in  the  oxalate,  C  8  O13 

One  allantoin,  -         -        -         -         C  8  H 5  N4  O 5 


C20  H13  N8  O21 

The  protoxide  of  lead  being  in  both  of  the  aggregates,  does  not  affect  the 
result  by  being  omitted  from  both. 

5377.  It  is  from  the  results  of  this  reaction  between  uric  acid  and  bioxide 
of  lead,  that  Liebig  has  inferred  the  existence  of  uril  as  above  mentioned 
(5319). 

5378.  Alloxan,  or  erythric  acid,  is  one  of  the  products  which  have  re- 
sulted from  the  decomposition  of  uric  acid.     To  prepare  alloxan,  one  part 
of  uric  acid  is  to  be  added  to  four  of  nitric  acid,  of  a  density  between  1.41 
and  1.5.    As  the  reaction  causes  much  heat  and  effervescence,  the  uric  acid 
should  be  added  in  successive  small  portions.     Little  white  granular  bril- 
liant crystals  are  gradually  formed,  until  the  whole  becomes  one  aggregate 
of  them,  which,  after  being  allowed  to  drain  in  a  glass  funnel,  must  be  dried 
on  porous  brick,  of  porcelain  earth.     By  re-solution  and  re-crystallization, 
the  crystals  of  alloxan,  thus  formed,  will  be  rendered  quite  pure. 

5379.  Alloxan  crystallizes  in  octahedra,  with  rhomboidal  bases,  colour- 
less, transparent,  very  brilliant,  and  often  of  an  inch  in  diameter.     They 
are  efflorescent,  losing  25  per  cent,  of  water.     By  a  gentle  heat,  alloxan, 
thus  crystallized,  is  rendered  anhydrous.     It  may  be  obtained  in  anhydrous 
crystals,  in  the  form  of  oblique  rhomboidal  prisms,  which  resemble  rhom- 
boidal octahedra  with  truncated  summits,  from  an  aqueous  solution  of  al- 
loxane  saturated  while  hot.     It  is  very  soluble  in  water,  has  a  nauseous 
smell,  and  a  salt  and  feebly  astringent  taste.     It  reddens  vegetable  colours, 
and  tinges  the  skin  purple.    By  reaction  with  alkalies,  it  is  decomposed  into 
alloxanic  acid.     Boiled  with  an  alkali,  it  is  transformed  into  urea  and  mes- 


488  ORGANIC  CHEMISTRY. 

oxalic  acid.  It  is  transformed  into  alloxantin  by  sulphuretted  hydrogen, 
chloride  of  tin,  or  metallic  zinc,  and  chlorohydric  acid.  An  excess  of  am- 
monia transforms  it  into  mycomelic  acid.  Nitric  acid  converts  it  into  para- 
banic  acid;  sulphuric  or  chlorohydric  acid  into  alloxantin;  sulphurous  acid 
and  ammonia  into  thionurate  of  ammonia ;  alloxantin  and  ammonia  into 
murexide.  Subjected,  simultaneously,  to  an  alkali  and  a  salt  of  protoxide 
of  iron,  it  produces  an  indigo-blue  liquid.  With  metallic  oxides  it  cannot 
combine  without  decomposition. 

5380.*  Alloxanic  acid  (supposed  anhydrous),  C4  N3  HO4;  is  produced 
'by  the  metamorphosis  of  alloxan  by  caustic  alkalies.  The  anhydrous  acid 
contains  the  elements  of  half  an  atom  of  alloxan,  minus  one  atom  of  water. 

5381.  Mesoxalic  acid  (hydrated),  C6  O9H  +  4HO;  or  rather  C3  O4  + 
2HO,  is  one  of  the  products  of  a  solution  of  alloxanate  of  baryta  or  stron- 
tian,  saturated  at  a  boiling  heat.    Also,  when  a  solution  of  alloxan  is  poured, 
drop  by  drop,  into  a  boiling  solution  of  acetate  of  lead,  a  very  heavy  granu- 
lar mesoxalate  of  lead  precipitates,  while  nothing  remains  in  the  acid  liquor 
besides  the  excess  of  acetate  of  lead  and  pure  urea.     Both  this  and  the  pre- 
ceding acid  may  be  separated  and  crystallized.     They  are  powerful  acids. 

5382.  Mycomelinic  acid,  C16  N8  H10  O10,  is  formed  on  adding  an  excess 
of  ammonia  to  a  solution  of  alloxan,  and  raising  the  mixture  to  the  boiling 
point.     It  is  almost  insoluble  in  cold  water,  and  is  thrown  down  as  a  yel- 
low gelatinous  precipitate,  which  becomes  a  yellow  porous  powder  on  dry- 
ing. 

5383.  Parabanic  acid,  C6  Na  O4  -f  2HO,  is  one  of  the  products  of  the 
decomposition  of  uric  acid  or  alloxan  by  nitric  acid,  discovered  by  Liebig 
and  Woehler.     It  is  prepared  by  dissolving  one  part  either  of  uric  acid  or 
alloxan  in  eight  parts  of  nitric  acid  of  ordinary  strength,  evaporating  the 
liquor  to  a  syrup,  and  allowing  it  to  crystallize. 

5384.  It  has  a  very  sour  taste,  resembling  that  of  oxalic  acid,  and  forms 
thin  transparent  six-sided  prismatic  crystals.     It  is  very  soluble  in  water 
and  does  not  effloresce;  it  is  in  some  degree  volatile. 

5385.  Oxaluric  acid,  C6  N2  IP  O7+  HO,  is  formed  on  adding  ammonia 
to  a  boiling  solution  of  parabanic  acid,  or  on  supersaturating  with  ammonia 
a  solution,  recently  prepared,  of  uric  acid  in  nitric  acid,  which  yields,  by 
evaporation,  crystals  of  oxalurate  of  ammonia.     The  acid,  when  separated, 
is  a  light  brilliant  white  crystalline  powder;  its  taste  is  very  sour,  and  it 
reddens  litmus.     Its  aqueous  solution  is  decomposed  completely  by  ebulli- 
tion, and  resolved  into  oxalic  acid  and  oxalate  of  urea.     It  is  formed  by  the 
combination  of  the  elements  of  parabanic  acid  with  two  atoms  of  water. 
The  crystallized  acid  contains  the  elements  of  two  atoms  of  oxalic  acid  and 
of  one  atom  of  urea,  and  may  be  considered  as  uric  acid  in  which  the  urile 
is  replaced  by  oxalic  acid. 

5386.  Thionuric  acid,  C8  N3  H5  O6  (S3  O6)  +  HO,  is  a  bibasic  acid 
produced  by  the  simultaneous  action  of  sulphurous  acid  and  ammonia  upon 
alloxan.     Liberated   from  thionurate  of  lead  by  sulphuretted  hydrogen,  it 
crystallizes  in  very  thin  needles,  is  persistent  in  air,  very  soluble  in  water, 
and  has  an  acid  taste.     It  contains  the  elements  of  one  atom  of  alloxan,  one 

*  Finding  Graham's  Elements  to  contain  an  abridgment  of  the  account  given  by 
Liebig,  of  the  compounds,  or  products,  of  uric  acid,  I  have  made  a  free  use  of  it,  with 
such  changes  in  the  language  as  to  make  it  my  own,  where  it  was  not  such  as  I 
should  have  used.  In  some  cases  I  have  made  a  similar  use  of  Kane's  Elements, 
and  of  Gregory's  Translations  from  Liebig,  especially  in  the  account  of  saliculous 
acid  and  its  compounds. 


OF  URIC  ACID.  489 

atom  of  ammonia,  and  two  atoms  of  sulphurous  acid.  On  heating  thionuric 
acid,  two  atoms  of  oxygen  of  the  alloxan  reunite  with  two  atoms  of  sul- 
phurous acid  to  form  sulphuric  acid,  while  the  elements  of  urile,  ammonia, 
and  water,  combine  and  give  rise  to  uramile. 

5387.  Uramile,  C8  N3  H5  O8,  is  prepared  by  adding  hydrochloric  acid 
to  a  saturated  and  boiling  solution  of  thionurate  of  ammonia,  till  it  is  strongly 
acid.     The  heat  is  continued  till  the  liquid  begins  to  become  turbid;  it  is 
then  allowed  to  cool  for  crystallization.     Uramile  crystallizes  in  thin  and 
hard  tufts;  or  presents  itself  in  the  form  of  a  brilliant  white  powder  com- 
posed of  very  thin  silky  needles.     It  is  sparingly  soluble  in  hot  water, 
wholly  insoluble  in  cold  water,  dissolves  in  ammonia  and  caustic  alkalies, 
and  is  again  precipitated,  without  alteration,  by  acids.     Either  diluted  acids 
or  a  solution  of  potash,  boiled  upon  uramile,  convert  it  into  uramilic  acid, 
disengaging  ammonia.     The  arnmoniacal  solution  of  uramile  becomes  pur- 
ple-red in  air,  and  deposits  crystalline  needles  of  a  green  colour  and  metal- 
lic lustre.     In  contact  with  oxide  of  mercury  or  oxide  of  silver,  it  is  decom- 
posed, by  ebullition,  into  murexide,  and  at  the  same  time  reduces  the  oxides 
to  the  metallic  state. 

5388.  Uramilic  acid,  C16  N5  H10  O15,  is  prepared  by  dissolving  thionu- 
rate of  ammonia  in  cold  water,  adding  to  the  saturated  solution  a  small 
quantity  of  sulphuric  acid,  and  evaporating  by  a  water-bath.     After  a  time, 
uramilic  acid  is  deposited  in  transparent  four-sided  prisms  of  a  vitreous  lus- 
tre, or  in  silky  needles.     It  is  soluble  in  six  or  eight  parts  of  cold  water, 
and  in  three  parts  of  boiling  water,  forming  a  feebly  acid  solution.    For  the 
creation  of  uramilic  acid,  two  atoms  of  uramile  unite  with  the  elements  of 
three  atoms  of  water,  yielding  up,  at  the  same  time,  the  elements  of  one 
atom  of  ammonia. 

5389.  Alloxantin.— Formula,  C8  Na  H5  O10.     Alloxantin  was  first  ob- 
served by  Dr.  Prout  among  the  products  of  the  decomposition  of  uric  acid 
by  nitric  acid,  and  more  lately  produced  and  studied  by  MM.  Liebig  and 
Woehler,  by  whom  several  processes  are  given  for  its  preparation.    1.  From 
uric  acid. — One  part  of  uric  acid  is  boiled  with  thirty-two  parts  of  water, 
and  dilute  nitric  acid  added,  by  small  portions  at  a  time,  till  the  uric  acid  is 
completely  dissolved,  and  the  liquor  evaporated  to  two-thirds.    In  the  course 
of  a  few  days,  or  sometimes  a  few  hours,  the  alloxantin  is  deposited  in  crys- 
tals, which  are  purified  by  new  crystallizations.     2.  From  alloxan. — It  is 
produced  in  large  quantity  by  conveying  a  stream  of  sulphuretted  hydrogen 
into  a  solution  of  alloxan.     Sulphur  is  first  deposited,  and  then  the  whole 
becomes  a  thick  mass  of  crystals  of  alloxantin,  which  are  separated  from 
sulphur  by  solution  in  boiling  water.    The  alloxantin  crystallizes  by  evapo- 
ration in  a  state  of  purity.     3.  On  exposing  a  solution  of  alloxan  to  the  ac- 
tion of  the  voltaic  battery,  oxygen  is  evolved  at  the  anode,  and  alloxantin  is 
deposited  at  the  cathode  in  crystalline  crusts. 

5390.  Alloxantin  crystallizes  in  oblique  prisms  of  four  sides,  which  are 
colourless  or  slightly  yellow,  hard,  and  easily  reduced  to  powder;  they  be- 
come red  in  air  impregnated  with  ammonia,  and  acquire  a  green  metallic 
lustre.     They  are  not  altered  at  212°,  but  at  302°  (150°  centig.)  lose  three 
atoms  of  water;  are  sparingly  soluble  in  cold  water,  more  soluble  in  boiling 
water;  the  solution  reddens  litmus.     Alloxantin  heated  in  chlorine-water, 
or  in  strong  nitric  acid,  is  changed  into  alloxan.    With  salts  of  silver  it  pro- 
duces a  black  precipitate  of  metallic  silver.     It  is  decomposed  by  alkalies; 
baryta-water  produces,  in  its  solution,  a  violet  precipitate,  which  is  made 
colourless  by  heat,  and  finally  disappears.     By  the  action  of  boiling  sui- 


490  ORGANIC  CHEMISTRY. 

phuric  acid,  two  atoms  of  alloxan  are  converted,  with  the  concurrence  of 
two  atoms  of  water,  into  one  atom  of  alloxantin,  three  atoms  of  oxalic  acid, 
two  atoms  of  ammonia,  and  two  atoms  of  carbonic  acid. 

5391.  The  circumstances  of  the  formation  of  alloxantin  are  thus  ex- 
plained by  M.  Liebig.     By  the  action  of  nitric  acid,  the  uril  of  the  uric 
acid  combines  with  one  atom  of  oxygen,  and  with  the  elements  of  five  atoms 
of  water,  giving  rise  to  one  atom  of  alloxantin,  and  to  quadroxide  of  nitro- 
gen, NO*,  which,  in  contact  with  water,  is  converted  into  nitrous  and  nitric 
acids;  the  nitrous  acid  is  decomposed,  and  half  of  the  urea  set  at  liberty; 
while  the  other  half  of  the  urea  forms,  with  nitric  acid,  nitrate  of  urea.     In 
the  process  with  sulphuretted  hydrogen,  one  atom  of  oxygen  of  the  alloxan 
combines  with  hydrogen  from  the  sulphuretted  hydrogen  to  form  water, 
which  remains  in  the  constitution  of  the  alloxantin ;  the  sulphur  set  free  is 
deposited. 

5392.  Products  of  the  decomposition  of  Alloxantin. — When  a  stream 
of  sulphuretted  hydrogen  is  carried  into  a  boiling  solution  of  alloxantin, 
more  sulphur  is  deposited,  and  on  saturating  the  solution  with  ammonia,  a 
salt  crystallizes  in  thin  colourless  needles,  of  which  the  formula  is  C8  N3 
H7  O3,  which  is  considered  a  compound  of  a  new  acid,  dialuric  acid,  with 
ammonia.     This  acid  is  resolved  into  new  products  when  liberated  by  ano- 
ther acid;  one  of  these  produced  by  exposure  to  air,  and  evaporation  of  the 
solution  of  the  ammoniacal  salt  in  dilute  sulphuric  or  hydrochloric  acid,  is 
dimorphous  alloxantin,  a  body  having  the  same  composition  as  alloxantin 
with  a  different  form.     On  mingling  boiling  solutions  of  sal  ammoniac  and 
alloxantin,  the  mixture  becomes  suddenly  of  a  purple-red  colour,  then  gra- 
dually loses  its  colour,  becoming  turbid,  and  deposits  colourless  brilliant 
plates  of  uramile,  which  become  rose-red  on  drying.     The  liquid  contains, 
after  its  decomposition,  alloxan  and  free  hydrochloric  acid.     When  a  solu- 
tion of  alloxantin  is  heated  with  caustic  ammonia,  uramile  and  mycomeli- 
nate  of  ammonia  are  first  formed,  but  are  decomposed  into  other  products 
by  the  prolonged  action  of  ammonia  and  air.     A  recent  solution  of  alloxan- 
tin in  ammonia  gradually  absorbs  oxygen  from  the  air,  and  deposits  crys- 
tals of  oxalurate  of  ammonia. 

Murexide. 

5393.  Formula,  C12  N5  H6  O8  (Liebig  and  Wcehler).     This  beautiful 
product  of  the  decomposition  of  uric  acid  was  first  described  by  Dr.  Prout, 
under  the  name  of  purpurate  of  ammonia.     Murexide  may  be  formed  by 
evaporating  a  solution  of  uric  acid  in  dilute  nitric  acid,  until  it  acquires  a 
flesh-red  colour,  and  treating  it,  when  cooled  to  160°,  with  a  dilute  solution 
of  ammonia,  till  the  presence  of  free  ammonia  is  perceptible;  the  liquid  is 
then  diluted  with  half  its  volume  of  water,  and  allowed  to  cool.     It  may 
also  be  formed  by  the  contact  of  ammonia  with  various  other  products  of 
the  reaction  of  nitric  acid  with  uric  acid,  with  ammonia,  with  or  without  the 
presence  of  atmospheric  air. 

5394.  The  following  method,  proposed  by  Liebig  and  slightly  modified 
by  Gregory,  appears  to  be  the  easiest  and  most  certain,  and  also  most  pro- 
ductive:— Seven  grains  of  hydrated  alloxan,  and  four  grains  of  alloxantin, 
are  dissolved  by  boiling  in  240  grains  of  water,  and  the  boiling  solution 
added  to  80  grains,  by  measure,  of  a  cold  and  strong  solution  of  carbonate 
of  ammonia.     This  mixture  has  precisely  the  proper  temperature,  and  de- 
posits very  fine  crystals  of  murexide.     The  experiment  is  not  so  successful 


OF  URIC  ACID.  491 

on  a  large  scale;  probably  because  the  liquid,  by  remaining  longer  warm, 
undergoes  a  partial  change.  It  is  best  to  try  first  a  saturated  solution  of 
carbonate  of  ammonia  in  cold  water.  If  it  do  not  yield  good  crystals,  add 
a  little  water,  and  repeat  the  experiment  till  a  solution  of  the  carbonate  is 
obtained,  which  gives  a  good  result.  The  difficulty  is  owing  to  the  sponta- 
neous formation  of  different  carbonates  by  the  action  of  water  on  the  car- 
bonate of  the  shops;  but  when  a  proper  solution  is  obtained,  the  experiment 
never  fails. 

5395.  Murexide  crystallizes  in  short  four-sided  prisms,  of  which  two 
faces,  like  the  upper  wings  of  cantharides,  reflect  a  green  metallic  lustre. 
The  crystals  are  garnet-red  by  transmitted  light.    Their  powder  is  reddish- 
brown,  and  acquires  a  green  lustre  under  the  burnisher.     Murexide  is  but 
slightly  soluble  in  cold  water,  but  colours  it  of  a  magnificent  purple;  it  dis- 
solves, however,  readily  in  water  at  158°,  and  crystallizes  again  as  the  so- 
lution cools.     It  is  insoluble  in  alcohol,  ether,  or  in  water  saturated  with 
carbonate  of  ammonia.     But  this  substance  cannot  be  purified  or  obtained 
in  crystals  of  large  size  by  crystallizing  it  from  boiling  water;  for  on  boil- 
ing murexide  in  a  small  quantity  of  water  for  the  time  necessary  to  dissolve 
the  whole,  the  crystals  become  colourless,  and,  upon  cooling,  a  yellow  gela- 
tinous matter  precipitates.     Hence,  probably,  the  slight  uncertainty  which 
attends  even  the  best  process  for  the  preparation  of  this  substance.     Murex- 
ide dissolves  in  a  solution  of  potash,  producing  a  superb  indigo-blue  colour, 
which  disappears  with  the  application  of  heat,  ammonia  being  disengaged. 
All  the  inorganic  acids  decompose  murexide,  precipitating  from  its  solution 
murexan  in  small  brilliant  plates.     Sulphuretted  hydrogen  decomposes  it 
immediately  into  alloxantin,  dialuric  acid  and  murexan,  while  sulphur  is  set 
free. 

5396.  Murexan,  C6  N3  H4  O3,  was  named  purpuric  acid  by  Prout.     It 
is  formed  on  dissolving  murexide  with  heat  in  caustic  potash,  heating  till 
the  blue  colour  disappears,  and  then  adding  an  excess  of  dilute  sulphuric 
acid.     It  crystallizes  in  colourless  plates  which  have  a  silky  lustre,  and  are 
very  brilliant;  is  insoluble  in  water  and  dilute  acids;  it  dissolves  in  ammo- 
nia and  other  alkalies,  in  the  cold,  without  neutralizing  them.     The  proper- 
ties of  murexan  closely  resemble  those  of  uramile.     Like  uramile,  murexan 
boiled  with  water,  red  oxide  of  mercury,  and  a  little  ammonia,  yields  mur- 
exide.    The  composition  of  murexan  and  uramile,  also,  not  differing  much 
in  100  parts,  Dr.  Gregory  admits  it  to  be  possible  that  these  two  substances 
may  be  essentially  the  same. 

5397.  As  the  habitudes  of  uric  acid,  and  of  the  substances  from  which  it 
may  be  generated,  or  to  which  it  may  give  rise,  must  be  an  object  of  inte- 
rest to  the  surgeon  and  physician,  I  have  deemed  it  proper  to  make  a  co- 
pious abstract  respecting  it  from  Graham.     I  do  not,  however,  as  respects 
other  bodies,  deem  it  expedient  to  go  farther  into  these  boundless  regions  of 
chemistry.     The  multiplication  of  compounds,  rendered  distinguishable  in 
their  properties  by  shifting  the  associations  of  ponderable,  with  imponderable 
matter,  seems  to  be  as  unlimited  as  the  images  which  may  be  produced  in 
the  kaleidoscope,  by  varying  the  relative  positions  of  the  coloured  beads: 
and  as,  in  a  majority  of  instances,  the  compounds  created  by  the  changes 
alluded  to,  have  either  the  electro-positive,  or  electro-negative  character, 
which  distinguishes  acids  and  bases  from  other  bodies;  so  it  must  happen 
that  there  will  be  a  prodigious  and  increasing  number  of  substances  stamped 
with  the  attributes  of  acidity  or  basidity.     Even  adepts  in  the  science  will 

63 


492  ORGANIC  CHEMISTRY. 

find  it  impossible  to  retain  any  available  knowledge  of  the  details  respecting 
such  compounds,  and  of  course,  however  important  it  may  be  to  register  all 
that  is  known  of  them  in  systematic  works,  in  a  text  book  it  can  answer  no 
good  purpose  to  dwell  on  that  which  could  not  be  remembered  even  if  it 
were  once  well  learned. 

5398.  I  propose,  however,  in  an  appendix,  to  give  some  alphabetical  ta- 
bles, in  which  the  information,  with  which  it  were  inexpedient  to  clog  the 
body  of  this  work,  may  be  found. 


On  the  Influence  of  Benzole  Acid  in  lessening  the  Generation 
of  Uric  Acid  in  Human  Urine. 

5399.  Allusion  has  been  made  to  the  discovery,  by  Mr. 
Alexander  Ure,  that  benzoic  acid,  taken  into  the  human 
stomach,  is  converted  into  hippuric  acid,  causing  a  diminu- 
tion of  the  uric  acid  generated  in  the  urine.     The  observa- 
tions and  inferences  of  Ure  have  been  confirmed  by  those 
of  Bouchardat,  who  alleges,  that  in  the  case  of  a  patient  in 
the  hospital  of  Hotel  Dieu,  at  Paris,  labouring  under  acute 
rheumatism,  and  whose  urine  was  depositing  an  abundance 
of  uric  acid,  the  spontaneous  deposition  of  the  acid  ceased 
after  the  due  administration  of  benzoic  acid :  also,  it  is  al- 
leged by  Mr.  Garrod,  that  having  repeatedly  performed 
tire's  experiment,  by  swallowing  from  a  scruple  to  half  a 
drachm  of  benzoic  acid  at  a  time,  he  had  always  been  ena- 
bled to  obtain  from  his  urine,  passed  three  or  four  hours 
subsequently,  on  the  addition  of  hydrochloric  acid,  from 
fifteen  to  twenty-nine  grains  of  hippuric  acid.* 

5400.  There  is,  however,  the  opposite  testimony  of  a 
commission  of  the  French  Academy  of  Sciences,  drawn  up 
by  Gay  Lussac  and  Pelouze,  that  they  could  not  find  any 
verification  of  the  results  of  Mr.  Ure.     Agreeably  to  the 
knowledge  which  I  have  obtained  respecting  the  manner 
in  which  such  commissions  are  managed  by  some  of  the 
most  distinguished  of  the  academicians,  I  attach  very  little 
importance  to  their  negative  testimony.     With  excellent 
intentions,  they  are  too  much  occupied,  too  much  dis- 
tracted, to  do  their  duty  well  in  such  cases. 

5401.  I  have  not  met  with  any  statement  tending  to  ex- 
plain in  what  manner  the  elements  of  benzoic  and  uric  acid 
can  give  rise  to  hippuric  acid. 

*  Bell's  Pharmaceutical  Journal,  London,  page  50.    No.  12.    June,  1842. 


OF  ORGANIC  ALKALIES.  493 

OF  ORGANIC  ALKALIES  OR  BASES, 
Also  called  Vegetable  Alkalies,  Vegeto-Alkalies,  or  Alkaloids. 

5402.  The  discovery  of  the  substances  which  bear  the 
above  mentioned  names,  is  of  the  highest  importance  to 
mankind.     It  has  enabled  the  physician  to  avail  himself  of 
the  active  principles  of  some  of  the  most  powerful  reme- 
dies, with  a  certainty  which  was  before  unattainable.    The 
patient,  in  lieu  of  being  nauseated  and  even  injured  by 
doses,  of  which  the  greater  part,  perhaps  the  whole,  may 
be  inert,  if  not  injurious,  has  to  swallow  nothing  which 
can  be  inefficacious,  when  judiciously  prescribed. 

5403.  The  organic  alkalies  are  entitled  to  rank  as  bases, 
under  the  definition  of  acidity,  deduced  from  the  practice 
of  chemists,  and  given  in  this  work  (note  631),  that  what- 
ever saturates  a  well  defined  acid  must  be  deemed  a  base. 

5404.  The  compounds  formed  with  acids  by  the  alkaline 
bases,  under  consideration,  resemble  those  formed  with 
metallic  oxybases;  their  acids  and  ingredients  being  no  less 
susceptible  of  precipitation  by  the  appropriate  tests.    Thus 
their  sulphates  are  liable  to  be  deprived  of  their  acids  by  a 
solution  of  baryta,  their  chlorides  by  solutions  of  silver  or 
lead.   There  is  in  this  respect  a  striking  difference  between 
the  habitudes  of  these  organic  alkaline  bases  and  those 
which  are  formed  of  oxidized  compound  radicals,  like  the 
oxides  of  ethyl,  formyl,  and  methyl,  which  cannot  be  trans- 
ferred from  one  acid  to  another,  unless  in  a  nascent  state, 
or  under  peculiar  circumstances.    Even  when  isolated,  the 
bases  last  mentioned  refuse  to  unite  with  hydrated  acids, 
which  is  far  from  being  the  case  with  the  alkaline  bases  in 
question.     Generally,  the  latter  differ  very  much  from  the 
alkalies  proper,  in  being  much  more  soluble  in  alcohol  than 
in  water.    In  consequence  of  this  last  mentioned  trait  their 
alkaline  reaction  with  vegetable  colours  is  very  feeble,  be- 
ing displayed  more  in  their  power  of  restoring  such  colours, 
than  by  directly  producing  the  changes  which  result  from 
solutions  of  the  inorganic  alkaline  bases. 

5405.  The  following  table  of  the  organic  alkalies  indi- 
cates their  sources  and  composition: — 


494 


ORGANIC  CHEMISTRY. 


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496  ORGANIC  CHEMISTRY. 

5406.  The  salts,  formed  by  the  organic  alkalies  with  oxacids,  always 
contain  the  elements  of  an  atom  of  water  essential  to  their  existence.     In 
this  respect  they  agree  in  their  habitudes  with  the  analogous  ammoniacal 
compounds  formed  with  the  same  acids.     But  in  uniting  with  chlorohydric 
acid,  or  other  halohydric  acids,*  no  water  is  requisite.    In  this  respect  also, 
there  is  an  agreement  between  their  habitudes  and  those  of  ammonia.    Hence 
it  might  be  reasonably  inferred  that  in  the  one  case  the  halogen  body  unites 
with  a  hydruret  of  the  organic  alkali,  while  in  the  other,  the  oxacid  unites 
with  an  oxide  of  such  a  hydruret.    This  theory  has  made  no  change  in  the 
names  of  ammoniacal  oxysalts ;  but  as  respects  haloid  compounds  it  has 
changed  muriate  of  ammonia  into  chloride  of  ammonium,  and  induced  an 
analogous  result  in  the  case  of  the  ammoniacal  compounds  of  each  halogen 
body.     Consistency  then  would  seem  to  require  that  a  like  change  should 
be  made  in  the  nomenclature  of  the  compounds  of  the  halohydric  acids 
with  the  organic  alkalies ;  but  we  have  had  no  proof  that  any  of  those  al- 
kalies are  metallized,  and  of  course  could  not  call  muriate  of  morphia  chlo- 
ride of  morphium.    Under  these  circumstances,  chlorohydruret  is  the  name 
to  which  I  would  resort  for  any  compound  of  chlorohydric  acid  with  an  or- 
ganic base.     In  practice,  however,  until  the  relation  between  ammonia  and 
these  alkalies  is  better  understood,  it  will  be  as  well  to  employ  the  officinal 
appellation  (muriate)  above  mentioned ;  keeping  the  other  in  view  in  order 
to  prevent  a  theoretic  misconception,  that  any  combination  can  be  formed 
with  an  organic  base  which  merits  to  be  designated  as  a  muriate. 

5407.  The  organic  alkalies  are,  for  the  most  part,  pro- 
ducts of  vegetation;  yet  the  following  substances,  not  de- 
rived from  vegetables,  are  alleged  to  be  allied  to  the  class 
of  vegetable  bases,  ammeline,  melamine,  aniline,  urea:  also 
some  substances  obtained  from  the  animal  oil  of  Dippel, 
called  severally  odorine,  ammoline*  and  animine. 

Organic  Alkalies  of  doubtful  Existence. 

5408.  "  The  following  bases  are  still  problematical :  api- 
rine,  azaridine,  blanchinine,  buxine,  carapine,  castine,  chi- 
occine,  crotonine,  cynapine,  daphnine,  digitaline,  esenbeck- 
ine,  eupatorine,  euphorbine,  fumarine,  glancine,  glaucopic- 
rine,  jamaicine,  menispermine,  paramenispermine,  pitayine, 
sanguinarine,  staphisaine,  surinamine,  violine.    Besides  two 
bases  in  Carthagena  quinquina  bark  and  in  chinova  bark." 
Graham's  Translation  from  Liebig,  983. 

Of  the  State  in  which  the  Organic  Alkalies  exist  in  the  Pro- 
ducts of  Vegetation,  and  the  Means  of  extricating  them, 
generally  described. 

5409.  The  organic  alkalies  appear  in  almost  every  in- 
stance to  exist  in  the  vegetables  to  which  they  belong,  in 

*  Halohydric  is  the  generic  name  which  I  apply  to  acids  formed  of  a  halogen  body 
and  hydrogen. 


OF  ORGANIC  ALKALIES.  497 

union  with  an  acid.  Thus,  morphia  is  united  with  sulphu- 
ric and  meconic  acid,  cinchonia  and  quinia  with  kinic  acid, 
delphia  with  malic  acid,  and  veratria  with  gallic  acid.  In 
some  instances,  the  acids  have  not  been  specified;  but  the 
method  requisite  for  the  analysis,  shows  that  they  are  pre- 
sent. The  salt  thus  formed  is  entangled  sometimes  with 
resinous  matter,  sometimes  with  colouring  matter,  at 
others  with  fatty  matter,  and  in  a  few  instances  with 
caoutchouc.  In  some  cases  several,  in  others  all  of  these 
impurities  may  be  present. 

5410.  In  the  extrication  of  the  organic  alkalies  charac- 
terized, and  situated  as  has  been  stated,  the  first  object  of 
the  chemist  will  be  to  employ  some  solvent  which  will  take 
up  the  native  salt  in  which  it  exists.  This  may  in  many 
cases  be  effected  by  water  alone;  but  an  aqueous  solution 
of  some  powerful  acid,  usually  sulphuric  or  chlorohydric 
acid,  appears  to  have  been  found  preferable.  The  next 
step  is  decomposition  of  the  salt  formed  with  the  organic 
base.  This  may,  of  course,  be  effected  by  any  stronger 
base,  and  accordingly,  potash,  soda,  ammonia,  lime,  and 
magnesia,  have  all  been  more  or  less  employed.  The  al- 
kali when  insoluble  in  water,  as  happens  in  a  great  majority 
of  cases,  precipitates  with  or  without  the  precipitant,  ac- 
cordingly as  the  compound  which  this  forms  with  the  acid 
is  or  is  not  soluble.  In  either  case,  the  next  object  to  be 
attained  is  to  extricate  the  organic  alkali  from  the  impuri- 
ties which  may  have  been  precipitated  with  it.  These  may 
consist  of  resinous  matter,  fatty  matter,  colouring  matter, 
caoutchouc,  &c.  To  remove  these,  washing  with  weak 
alcohol,  ether  and  water,  has  been  employed,  or  re-solution 
in  an  acid,  and  subjection  to  the  depurating  and  decolori- 
zing efficacy  of  animal  charcoal.  Repeated  solution  and 
recrystallization  by  means  of  alcohol,  or  acids,  are  also 
used  to  effect  a  final  depuration.  When  the  alkali  to  be 
extricated  is  soluble  in  water,  and  volatile  as  in  the  in- 
stance of  conicine,  the  leaves,  flowers,  roots  or  seed,  are 
subjected,  with  a  weak,  aqueous,  alkaline  solution,  to  the 
distillatory  process.  The  water  which  distils  in  conse- 
quence, contains  more  or  less  of  the  organic  alkali,  as  well 
as  some  ammonia  resulting  from  its  decomposition.  Being 
first  neutralized  by  diluted  sulphuric  acid,  then  concentra- 
ted by  evaporation,  and  afterwards  digested  in  a  close  ves- 
sel with  ether,  this  liquid  dissolves  the  organic  alkali, 


498  ORGANIC  CHEMISTRY. 

which  may  of  course  be  easily  isolated  by  subsequent  ex- 
posure to  a  water  bath  sufficiently  heated  to  expel  the  ether 
and  ammonia. 

541 1.  In  some  instances  the  decomposition  of  the  native 
salts  in  which  the  organic  alkalies  are  constituents,  may 
be  effected  by  acetate  of  lead.     As  this  metal  generally 
forms  insoluble  compounds  with  vegetable  acids,  by  com- 
plex affinity  the  acid  goes  to  the  oxide  of  that  metal,  while 
the  alkali  combines  with  acetic  acid.     From  the  solution 
of  the  acetate  thus  formed,  the  lead  of  any  excess  of  the 
acetate  of  lead  may  be  precipitated  by  sulphydric  acid.* 

Of  Morphia  or  Morphine. 

5412.  Morphia,  the  most  important  among  the  active 
principles  of  opium,  was  discovered  by  Serturner,  of  Eim- 
bech,  in  Hanover,  and  recognised  by  him  as  an  organic 
alkali.     This  formed  the  first  step  in  a  new  career  in 
chemical  discovery,  having  induced  those  subsequent  re- 
searches by  other  chemists,  to  which  we  are  indebted  for 
our  knowledge  of  the  series  of  analogous  principles  men- 
tioned in  the  preceding  table. 

5413.  Morphia  exists  in  opium  in  chemical  union  with 
meconic  acid  only,  but  is  mechanically  associated  with 
various  substances,  of  which  an  account  has  been  given. 
(5172.) 

5414.  It  is  remarkable,  that  since  we  have  learned  the 
existence  of  morphia,  it  has  become  evident  that  the  means 
of  detecting  its  presence  in  laudanum,  almost  extempora- 
neously, had  long  been  at  hand  in  the  shop  of  every  drug- 
gist.    Dr.  Staples,  a  graduate  of  our  school,  demonstrated, 
about  twenty  years  ago,  that  to  cause  a  precipitation  of 
crystals  of  morphia,  it  were  only  requisite  to  add  to  that 
tincture  equal  parts  of  liquid  ammonia  and  alcohol.     The 
crystals  thus  obtained,  being  redissolved  by  acetic  acid, 

*  The  following  process  for  elaborating  the  organic  alkalies,  suggested  by  M.  O. 
Henry,  is  founded  on  the  property  of  tannic  acid  to  precipitate  the  organic  alkalies 
in  general. 

Neutralize  by  potassa  a  clear  infusion  obtained  by  digesting  the  vegetable  matter 
containing  the  alkali,  or  an  extract  procured  from  it,  in  tepid  water,  acidulated  by 
sulphuric  acid  :  add  an  infusion  of  galls  so  long  as  any  precipitate  ensues.  The  pre- 
cipitate, after  being  washed  with  cold  water,  is  to  be  thoroughly  mingled  with  hy- 
drate of  lirne,  somewhat  in  excess,  and  being  dried  by  the  heat  of  boiling  water, 
must  be  digested  in  alcohol  or  ether.  The  resulting  solution,  after  filtration,  is  to  be 
subjected  to  a  heat  sufficient  to  drive  off  the  alcohol.  The  residual  liquid,  consisting 
of  water  which  had  been  in  combination  with  the  alcohol,  holds  the  alkali  in  solu- 
tion, and  after  a  few  days  repose  deposits  it  in  crystals. 


OF  MORPHIA  OR   MORPHINE.  499 

and  again  precipitated  by  ammonia,  may  be  purified  of  the 
matter  by  which  they  are,  in  the  first  instance,  discoloured. 
A  particular  account  of  an  improved  process,  devised  by 
Dr.  Staples,  may  be  found  in  the  United  States  Dispensa- 
tory, by  the  editors  of  which  it  is  highly  recommended. 

5415.  The  following  process,  suggested  by  Wittstoch, 
is  recommended  as  probably  the  best,  by  Kane. 

5416.  One  part  of  opium,  from  eight  to  ten  of  water, 
with  two  of  chlorohydric  acid,  are  to  be  digested  together 
for  six  hours.     The  solution  being  then  decanted,  the  resi- 
due is  to  be  subjected  twice  successively  to  the  same  or- 
deal.    The  resulting  solutions  being  united,  the  whole  is 
to  be  saturated  with  chloride  of  sodium.      The  matter 
which  consequently  subsides,  is  to  be  separated  by  filtra- 
tion, and  ammonia  being  added,  in  slight  excess,  to  the  fil- 
tered liquid,  it  must  be  allowed  to  rest  undisturbed  for 
twenty-four  hours.     The  resulting  precipitate  is  to  be  col- 
lected upon  a  filter,  washed  with  a  little  water,  dried,  and 
digested  in  alcohol,  of  0.820,  which  takes  up  the  morphia. 
The  greater  part  of  the  spirit  being  removed  by  distilla- 
tion, morphia  crystallizes  on  cooling  in  a  state  sufficiently 
pure. 

5417.  The  effect  of  the  chloride  of  sodium  is  to  preci- 
pitate narcotina,  and  some  other  impurities.     The  meco- 
nin,  codeia,  thebaine,  and  some  other  principles,  are  re- 
tained in  solution  by  the  alcoholic  mother  liquor. 

5418.  Morphia  crystallizes  in  rhombic  prisms,  contain- 
ing for  each  atom,  two  of  water,  which  are  liable  to  be 
lost  by  efflorescence.     It  has  an  enduring  bitter  taste,  and 
is  almost  insoluble  in  water,  as  it  requires  for  solution  400 
parts,  even  at  the  temperature  of  ebullition,  and  precipi- 
tates, almost  entirely,  as  the  liquid  cools.     It  has  an  alka- 
line reaction,  readily  dissolves  in  alcohol,  but  sparingly  in 
ether.     It  is  also  soluble  in  aqueous  solutions  of  the  al- 
kalies and  earths. 

5419.  As  usually  procured,  this  alkali,  or  any  of  its 
combinations,  is  reddened  when  brought  into  contact  with 
nitric  acid.     The  phenomenon  is  produced  by  the  same 
acid  on  contact  with  other  vegeto-alkalies,  and,  according 
to  Kane,  is  not  produced  with  morphia  when  absolutely 
pure.     Subjected  to  chlorine  in  water,   morphia   is  first 
made  orange  red,  and  then  dissolved.     On  contact  with 
morphia,  the  iodine  of  iodic  acid  is  liberated.     A  solution 

64 


500  ORGANIC  CHEMISTRY. 

of  sesquichloride  of  iron  assumes  a  rich  blue  colour  on  the 
addition  of  morphia,  or  any  of  its  salts.  With  tannic  acid 
morphia  affords  a  copious  white  precipitate.  It  is  capable 
of  neutralizing  the  strongest  acids,  and  of  forming  with 
them  compounds  which  are  soluble  and  crystallizable. 

5420.  Agreeably  to  the  late  observations  of  Larocque 
and  Thibierge,  the  perchloride  of  gold  produces  with  mor- 
phia a  precipitate  which  is  at  first  yellow,  next  bluish,  and 
lastly  violet.     In  the  state  in  which  it  assumes  the  colour 
last  mentioned,  the  gold  is  revived;  while  the  precipitate, 
of  which  it  forms  a  part,  becomes  insoluble  in  water,  alco- 
hol, caustic  alkalies,  or  in  sulphuric,  nitric,  or  chlorohydric 
acids.     Yet  with  aqua  regia,  it  makes  a  solution  which  is 
precipitated  by  the  green  sulphate  of  iron. 

5421.  With  the  oxacids,  with  organic  acids,  and  with 
the  halogen  bodies,  morphia  generates  salts  which  are  ca- 
pable of  crystallization  and  of  being  dissolved  by  water. 
The  medicinal  properties  of  the  alkali  are  not  impaired  by 
these  combinations.     In  this  country  the  sulphate  is  the 
most  used ;  but  Dr.  Kane  alleges  the  "  muriate  "  to  be  the 
most  important  compound  of  morphia. 

Of  Paramorphia^  or  Thebaine. 

5422.  Paramorphia  is  an  alkali  lately  discovered  by  Pel- 
letier  in  minute  proportion  in  opium.     It  is  identical  with 
morphia  in  composition,  but  quite  distinct  in  its  properties. 
It  is,  therefore,  isomeric  with  morphia,  and  hence  its  name. 

5423.  Paramorphia  is  white,  scarcely  soluble  in  water, 
of  an  acrid  and  styptic,  rather  than  a  bitter  taste,  and  very 
soluble  in  alcohol  or  ether,  even  when  cold,  and  still  more 
so  when  hot.     It  differs  from  morphia  in  not  being  redden- 
ed by  nitric  acid,  in  not  forming  crystallizable  salts  with 
acids,  and  in  not  striking  a  blue  colour  with  the  salts  of 
iron.     It  also  differs  from  morphia  in  its  action  on  the 
system,  producing  tetanic  symptoms  in  doses  of  a  grain. 

5424.  Pseudomorphia  is  a  name  given  to  another  alkali 
discovered  by  the  same  distinguished  chemist  in  opium, 
likewise  in  minute  proportion.     It  resembles  morphia  in 
the  characteristic  properties  of  becoming  red  with  nitric 
acid,  and  of  striking  a  blue  colour  with  the  salts  of  iron, 
and  yet  differs  from  it  in  not  being  poisonous.     It  is  not 
always  present  in  opium,   and   the  circumstances  under 
which  it  is  produced  are  not  known. 


OF  CODEIA,  NARCOTINA,  NARCEIA  AND  QUINIA.  501 

Of  Codeia,  or  Codeine. 

5425.  This  vegetable  alkali  was  discovered  in  1832,  by 
Robiquet.     It  exists  in  opium  as  a  meconate.     It  is  in  the 
form  of  colourless  crystals,  which  are  soluble  in  two  parts 
of  boiling  water,  also  soluble  in  alcohol  and  ether,  but  in- 
soluble in  alkaline  solutions.     Its  capacity  of  saturation 
is  very  nearly  the  same  as  that  of  morphia ;  but  it  may  be 
distinguished  from  that  alkali  by  the  different  form  of  its 
crystals,  x  by  its  greater  solubility  in  water,  and  by  its  in- 
solubility in  alkaline  solutions.     It  has  a  decided  action 
on  the  animal  economy,  producing  first  excitation,  and  af- 
terwards depression. 

Of  Narcotina,  or  Narcotine. 

5426.  In  order  to  obtain  narcotina,  opium  may  be  com- 
minuted, and  digested  with  as  much  ether  as  will  cover  it, 
at  a  temperature  near  the  boiling  point  of  the  ether,  for 
three  or  four  days.     The  ether  being  decanted  and  allow- 
ed to  evaporate,  the  narcotina  will  appear  in  slender  pris- 
matic crystals,  soiled  by  caoutchouc,  resin,  and  colouring 
matter.     Being  subjected  to  boiling  alcohol  and  recrys- 
tallized  by  refrigeration  therefrom,  they  are  rendered  purer, 
and  further  purified  by  repeated  solution  and  recrystalliza- 
tion.     To  remove  all  the  narcotina,  opium  must  be  sub- 
jected to  successive  portions  of  ether. 

Of  Narceia,  or  Narceine. 

5427.  This  alkali  was  discovered  in  opium  by  Pelletier 
in  1832.     It  exists  in  white,  silky,  acicular  crystals,  ino- 
dorous, of  a  slightly  bitter  taste,  sparingly  soluble  in  water, 
more  soluble  in  alcohol,  and  insoluble  in  ether.     It  is  ren- 
dered blue  by  the  dilute  mineral  acids,  but  does  not,  like 
morphia,  become  blue  with  the  salts  of  iron,  nor  red  with 
nitric  acid. 

Of  Quinia,  or  Quinine. 

5428.  In  the  various  kinds  of  cinchonia,  known  in  com- 
merce as  Peruvian  bark,  there  are  three  organic  alkalies, 
quinia,  cinchonia,  and  aricina,  of  which  the  most  impor- 
tant is  that  which  bears  the  name  at  the  head  of  this  pa- 
ragraph.    Quinia  is  generally  procured  from  yellow  bark. 
The  process  usually  employed   for  its  elaboration  is  as 
follows.     The  bark,  coarsely  powdered,  is  boiled  with  sul- 


502  ORGANIC  CHEMISTRY. 

phuric  or  chlorohydric  acid.  In  the  case  of  sulphuric  acid, 
the  proportions  given  are  three  fluid  drachms  to  a  gallon  of 
water;  in  the  other  case,  two  of  acid  to  ten  of  water;  a 
pound  of  bark  being  employed. 

5429.  The  bark  is  to  be  subsequently  exposed  to  a  simi- 
lar ordeal  with  a  half,  and  with  a  fourth  part  of  the  quan- 
tity of  acid  at  first  employed.     To  the  united  solutions, 
strained  and  cooled,  add  hydrate  of  lime  till  there  be  an 
alkaline  reaction.      The   precipitate   is  to   be   collected. 
This,  when  sulphuric  acid  is  used,  will  consist  in  part  of 
sulphate  of  lime;  but  when  the  other  solvent  is  used,  the 
lime  will  remain  in  solution  in  the  state  of  chloride.     In 
either  state,  the  precipitate  being  digested  in  alcohol,  the 
alkali  is  taken  up.     The  solution  thus  formed,  is  subjected 
to  distillation  with  water.     The  residue  being  treated  with 
sulphuric  acid  in  excess,  on  evaporation  affords  crystals  of 
sulphate  of  quinia;  the  sulphate  of  cinchonia  remaining 
in  solution.     From  the  sulphate,  pure  quinia  may  be  ob- 
tained by  adding  to  a  solution  of  it  caustic  potash,  also 
in  solution,  drying  the  resulting  precipitate,  dissolving  it 
in  a  quantity  of  alcohol,  as  small  as  possible,  and  allowing 
the  liquid  thus  obtained  to  evaporate  leisurely  in  a  place 
moderately   warm.      Under   these   circumstances,   quinia 
crystallizes  in  union  with  an  atom  of  water,  forming  of 
course  a  crystalline  hydrate.      This   water   it   loses   by 
fusion.     Quinia  is  intensely  bitter.     It  requires  for  solu- 
tion, two  hundred  parts  of  hot  water,  and  is  almost  insolu- 
ble in  cold  water.     In  alcohol  or  ether  it  dissolves  readily. 
The  salts  of  this  alkali  are  soluble  in  water,  as  well  as  in 
alcohol,  and  are  capable  of  crystallizing.     In  common  with 
those  of  other  alkalies,  and  of  ammonia,  the  oxysalts  which 
it  forms,  require  an  atom  of  water,  as  already  mentioned 
(5406). 

5430.  Of  the  Chlorohydruret  or  Muriate  of  Quinia.  This 
salt  forms  pearly  crystalline  needles,  which  are  very  solu- 
ble in  water.     It  acts  as  a  base  with  chloroplatinic,  or 
chlorohydrargyric  acid  (corrosive  sublimate),  forming  what 
are  called  double  salts  by  some  chemists,  but  which  I  con- 
ceive should  be  called,  severally,  chloroplatinate  or  chloro- 
hydrargyrate  of  the  chlorohydruret  of  quinia ;  or  for  the 
sake  of  brevity,  as  in  other  cases,  simply  a  chloroplatinate 
of  morphia,  or  chlorohydrargyrate  of  quinia  (5406). 

5431.  Basic  Sulphate  of  Quinia  consists  of  two  atoms 


OF  Q.UINIA.  503 

of  quinine,  one  of  sulphuric  acid,  and  eight  of  water;  its 
formula  being  Qu  So3  8HO.  The  manufacture  of  this 
compound  is  conducted  on  a  large  scale,  according  to  the 
process  above  given  for  the  extrication  of  quinine,  and  va- 
rious other  methods.  In  crystallizing,  this  sulphate  enters 
into  combination  with  six  atoms  of  water  of  crystalliza- 
tion, and  two  acting  as  a  base.  Hence  in  dry  air,  or  when 
gently  heated,  it  relinquishes  six,  yet  retains  two,  which 
cannot  be  expelled  without  partial  decomposition.  This 
salt  is  but  sparingly  soluble  in  water,  requiring  thirty  parts 
at  a  boiling  heat,  and  seven  hundred  and  forty  in  the  cold. 
Of  alcohol,  unaided  by  heat,  it  requires  eighty  parts  for 
solution;  but  much  less  at  the  temperature  of  ebullition. 
Its  crystals  are  small  pearly  plates  or  needles,  which,  when 
heated,  fuse,  and  phosphoresce  vividly,  being  totally  decom- 
posed at  a  high  temperature. 

5432.  Neutral  Sulphate  of  Quinia. — This   salt   crystal- 
lizes in  rectangular  prisms,  of  which  the  formula  is  Qu  So3 
8HO.     They  are  prone  to  effloresce,  dissolve  in  ten  parts 
of  water  at  60°,  and  undergo  aqueous  fusion   at   112°. 
This  sulphate  is  very  soluble  in  alcohol,  and,  though  from 
its  constitution  it  should  be  neutral,  reddens  litmus. 

5433.  Basic  Sulphate  of  Quinia  of  Commerce. — In  the 
state  in  which  basic  sulphate  of  quinia  is  sold  in  com- 
merce, under  the  name  of  sulphate,  it  is  sometimes  adulte- 
rated with  boric  acid  and  with  sulphate  of  lime.     These 
substances  may  be  detected  by  exposing  the  aggregate  to 
a  red  heat,  by  which  the  elements  of  the  sulphate  may  be 
dissipated,  and  the  adulterations  exposed  to  view.     Sugar 
and  margaric  acid  have  also  been  used  as  adulterations. 
Of  these,  the  latter  may  be  detected  by  its  insolubility  in 
diluted  acids,  the  former  by  washing  a  sample  in  water, 
and  adding  carbonate  of  soda  to  precipitate  the  quinia, 
when  the  sweet  taste  of  the  sugar  will  become  perceptible. 

5434.  Phosphate  of  Quinia  crystallizes  in  small,  but  bril- 
liant needles,  soluble  both  in  water  and  in  alcohol. 

5435.  Ferroprussiate,  or  Cyanoferrite,  of  Quinia  is  formed 
by  boiling  one  part  sulphate  of  quinia,  and  one  and  a  half 
of  cyanoferrite  of  potassium,  in  seven  of  water.     The  ge- 
nerated salt  separates  as  greenish  yellow,  oily  substance. 
The  mother  liquor  being  decanted  when  cold,  the  cyano- 
ferrite is  to  be  redissolved  in  boiling  alcohol,  whence  on 
refrigeration  it  crystallizes  in  greenish  yellow  needles. 


504  ORGANIC  CHEMISTRY. 

On  the  Reaction  of  Chlorine  with  Quinia  and  its  Salts. 

5436.  If  sulphate  of  quinia  be  made  to  form  a  dilute  so- 
lution with  water,  impregnated  with  chlorine,  and  liquid 
ammonia  be  added,  a  green  precipitate  ensues,  the  liquid 
assuming  an  intensely  green  colour.      The   precipitated 
substance  has   been  called  dalleiochin.      If  the   residual 
green  liquid  be  evaporated  with  access  of  air,  it  changes 
to  dark  red,  while  sal  ammoniac  is  generated,  and  two 
bodies,  of  which  only  one  is  soluble  in  alcohol.     The  solu- 
ble   body   is   called    rusiochin,    the   other,    melanochin. 
Kane's  Elements. 

Of  Cinchonia,  or  Cinchonine. 

5437.  This  alkali  abounds  in  the  gray  bark  (cinchona 
micrantha)  from  which  it  may  be  extricated  by  means  ana- 
logous to  those  employed  in  the  case  of  quinia.     Usually 
it  is  obtained  from  the  mother  waters  of  the  sulphate  of 
the  alkali  last  mentioned,  by  saturating  the  excess  of  acid 
by  which  it  is  retained  in  solution  during  the  crystalliza- 
tion of  the  sulphate  of  quinia.     Under  these  circumstances, 
being  precipitated  by  an  alkaline  base,  and  afterwards  re- 
dissolved  by  alcohol,  it  is  obtained  in  thin,  colourless,  pris- 
matic crystals,  by  vaporizing  this  solvent.     Its  taste  is 
peculiar,  as  well  as  bitter.     Boiling  water  only  takes  up 
2rW  part;  but  it  readily  dissolves  in  alcohol  and  ether.    It 
fuses  at  330°  without  loss.     Between  its  salts  and  those  of 
quinia,  there  is  a  great  resemblance. 

5438.  The  chlorohydruret  of  cinchonia  crystallizes  in  bril- 
liant interwoven  needles,  and  like  the  congenerous  com- 
pound of  quinia  (5389)  acts  as  a  base  with  electronegative 
chlorides,  such  as  chloroplatinic,   and  chlorohydrargyric 
acid. 

5439.  Basic  sulphate  of  cinchonia,  C2  +  SO3  forms  rhom- 
bic prismatic  crystals,  which  require  for  solution  54  parts 
of  water.    The  neutral  sulphate  holding  only  half  as  much 
base,  is  more  soluble,  crystallizing  in  large  well  formed 
rhombic  octohedrons. 

Of  Aricina,  or  Aricine. 

5440.  This  alkali  was  discovered  in  1829  by  Pelletier 
and  Coriol,  in  a  bark  brought  from  Arica,  on  the  Pacific 


OF  STRYCHNIA  AND  BRUCIA.  505 

coast  of  South  America,  which  was  fraudulently  mixed 
with  the  Calisaya  bark.  It  is  a  white,  transparent,  crys- 
talline substance,  having  a  warm  and  intensely  bitter  taste, 
which  is  long  in  developing  itself.  It  dissolves  in  alcohol 
and  ether,  but  is  completely  insoluble  in  water.  By  nitric 
acid  it  is  coloured  green.  The  salts  agree  in  their  proper- 
ties with  those  of  quinia  and  cinchonia. 

Of  Strychnia,  or  Strychnine. 

5441.  The  poisonous  principle  of  the  Strychnos  nux 
vomica,  and  Strychnos  ignatia  or  colubrina,  is  considered 
as  an  alkali,  and  called  strychnia.    It  may  be  developed  by 
a  process  similar  to  that  used  for  morphia.     It  was  origi- 
nally obtained  by  Pelletier  and  Caventou,  by  subjecting 
the  bean  of  the  Strychnos  ignatia,  duly  rasped,  to  nitric 
ether  in  a  Papin's  digester,  to  remove  fatty  matter;  and 
subsequent  exposure  of  the  residue  to  alcohol,  in  which 
the  strychnia,  in  union  with  an  acid,  dissolves.     The  alco- 
hol having  been  evaporated,  and  the  residuum  dissolved  in 
water,  the  addition  of  potash  caused  the  alkali  to  precipi- 
tate.    It  was  afterwards  washed  in  cold  water,  and  redis- 
solved  in  alcohol,  from  which  it  crystallized  by  evapora- 
tion. 

5442.  The  colour  of  strychnia  is  white.     Its  taste  is 
intolerably  bitter,   leaving   a  metallic  impression  in   the 
mouth.     It  is  nearly  insoluble  in  water,  or  ether,  but  is 
very  soluble  in  alcohol.     It  is  a  terrible  poison,  very  small 
quantities  producing  tetanus  to  a  fatal  extent;  being  used 
by  the  natives  of  Borneo  to  render  their  arrows  poisonous, 
under  the  names  either  of  upas  tieuta,  or  woorara. 

Of  Brucia,  or  Brucine. 

5443.  This  alkali  exists  in  the  bark  of  the  Brucia  anti- 
dysenterica,  or  false  angustura.     The  bark  was  first  sub- 
jected to  sulphuric  ether,  and  afterwards  to  alcohol.     The 
alcohol  being  evaporated,  afforded  a  dry  residuum,  which 
was  dissolved  in  water.     The  solution  in  water  was  satu- 
rated with  oxalic  acid,  and  evaporated  to  dryness.     An 
oxalate  of  brucia  resulted,  which,  after  being  depurated  by 
alcohol  of  colouring  matter,  with  which  it  was  associated 
and  disguised,  was  decomposed  by  lime  or  magnesia.     As 
either  of  these  bases  forms  an  insoluble  salt  with  oxalic 


506  ORGANIC  CHEMISTRY. 

acid,  while  brucia  is  soluble  in  500  times  its  weight  of 
boiling  water,  or  in  850  parts  of  cold,  it  was  separated 
from  the  insoluble  oxalate  by  water. 

5444.  Brucia  crystallizes  in  oblique  prisms,  with  paral- 
lelograms for  their  bases.     It  is  less  bitter  than  strychnia, 
but  its  taste  is  more  acrid  and  durable.     It  melts  when 
heated  a  little  above  212°,  and  congeals  on  cooling  into  a 
mass  resembling  wax.     It  neutralizes  acids,  affording  a 
distinct  class  of  salts.     On  animals,  its  effects  are  analo- 
gous to  those  of  strychnia,  but  less  violent.* 

Of  Delphia,  or  Delphine. 

5445.  It  was  in  the  seeds  of  the  Delphinium  staphisa- 
gria,  or  stavesacre,  in  which  it  exists  as  a  malate,  that  this 
alkali  was  detected.     A  decoction  of  the  seeds,  which  had 
been  cleansed  and  reduced  to  a  pulp,  was  filtered.     The 
fluid,  which  passed  the  filter,  was  boiled  with  magnesia, 
which  liberated  the  delphia.     It  was  then  separated  from 
the  magnesia  by  alcohol,  and  from  this  solvent  by  evapo- 
ration. 

5446.  Delphia  is  white,  pulverulent,  and  very  soluble  in 
alcohol  and  ether.   It  is  inodorous,  but  its  taste  is  extreme- 
ly acrid  and  bitter.     Water  derives  from  it  an  acrid  taste, 
though  it  does  not  dissolve  any  appreciable  quantity.     By 
combination  with  acids,  it  forms  neutral  salts,  which  are 
soluble  in  water,  and  very  acrid  and  bitter. 

5447.  Concentrated  sulphuric  acid  reddens,  and  after- 
wards  carbonizes   delphia.      Chlorine    renders   it   green. 
Courbe  alleges  that  stavesacre  contains,  in   addition  to 
that  which  has  been  described,  a  yellow,  resinous  sub- 
stance, of  which  the  formula  is  C32  H23  O4  N;  and  the  name 
suggested  for  it  is  staphysain.     This  is  distinguished  by 
insolubility  in  ether,  or  water;    and  solubility  in  dilute 
acids,  without  neutralizing  them. 

*  Mr.  Fuch  advances  that  brucia  is  a  combination  of  strychnia  with  a  resin 
which  this  last  mentioned  substance  holds  obstinately,  and  which  has  the  pro- 
perty of  being  reddened  by  nitric  acid.  It  is  to  this  impurity  that  brucia  owes  its 
liability  to  be  made  red  by  the  acid  above  mentioned.  Mr.  Fuch  has  found  a  method 
of  separating  this  resin  from  brucia,  and  consequently  of  converting  this  supposed 
peculiar  alkali  into  strychnia.  He  has  not,  however,  succeeded  in  causing  strychnia 
to  combine  with  the  resin  in  question  so  as  to  form  brucia.  Although  Mr.  Fuch 
mentioned  it  to  be  his  intention  to  publish  his  process  for  the  depuration  of  brucia, 
a  year  has  elapsed  without  any  further  information  having  been  promulgated  by  him 
on  this  subject.  Berzelius'  Report  for  1841,  p.  141. 


OF  VERATRIA  AND  SABADILLA.  507 

Of  Veratria,  or  Veratrine. 

5448.  Veratria  is  an  alkali  obtained  from  the  seed  of 
the  Veratrum  sabadilla;  also  from  the  roots  of  the  Vera- 
trum  album  (white  hellebore),  and  Colchicum  autumnale 
(meadow  saffron). 

5449.  The  seeds,  partially  depurated  by  digestion  with 
ether,  yielded   a  coloured  tincture   with  heated  alcohol. 
This  tincture  deposited  some  waxy  matter  on  cooling, 
and  by  evaporation  afforded  a  residuum,  soluble  in  water, 
excepting  a  small  portion  of  extraneous  matter.     The  wa- 
tery solution  being  slowly  and  partially  evaporated,  until 
an  orange-coloured  precipitate  ceased  to  appear,  acetate 
of  lead  was  added  to  it.     A  copious  yellow  precipitate  en- 
sued, and  the  liquor,  being  separated  from  it  by  a  filter, 
became  almost  colourless.     This  fluid  was  subjected  to 
sulphydric  acid,  to  precipitate  any  lead  which  it  might 
contain.    The  solution  then  gave,  with  magnesia,  a  precip- 
itate, from  which  alcohol  took  up  veratria.    From  the  al- 
coholic solution,  the  veratria  was  afterwards  isolated  by 
evaporation. 

5450.  Veratria  is  white,   pulverulent,   and   inodorous, 
but,  nevertheless,  poisonous  when  inhaled,  producing  vio- 
lent and  dangerous  sneezing.     Its  taste  is  not  bitter,  but 
excessively  acrid.     It  reacts  like  an  alkali,  is  insoluble  in 
water,  but  very  soluble  in  alcohol  and  ether.     It  melts  at 
230°.     Its  salts  are  for  the  most  part  crystallizable  and 
neutral,  but  decomposable  by  water  into  free  acid,  and  a 
basic  salt.     Taken  into  the  stomach  in  minute  quantities, 
it  produces  intolerable  nausea  and  vomiting,  and  in  large 
doses,  death. 

Of  Sabadilla. 

5451.  Sabadilla  was  discovered  by  Couerbe,  as  an  al- 
kali accompanying  veratria  in  veratrum  sabadilla,  and  in 
the  roots  of  the  Veratrum  album  (white  hellebore),  and 
Colchicum  autumnale  (meadow  saffron). 

5452.  By  boiling  the  precipitate,  obtained  by  carbonate 
of  soda  from  an  infusion  of  sabadilla  seeds  in  diluted  sul- 
phuric acid,  sabadilla  may  be  separated  in  radiated  needles, 
of  a  pale  rose  colour,  which  may  be  rendered  white  by  de- 
puration.    This  alkali  is  a  white,  crystallizable  substance, 

65 


508  ORGANIC  CHEMISTRY. 

in  supportably  acrid,  fusible  by  heat,  readily  soluble  in  hot 
water,  very  soluble  in  alcohol,  and  wholly  insoluble  in 
ether. 

Of  Jervina,  or  Jervine. 

5453.  Jervina  is  found  in  veratrum  album,  associated 
with  veratrine,  from  which  the  sparing  solubility  of  its 
sulphate,  and  its  readiness  to  crystallize  from  an  alcoholic 
solution  with  four  atoms  of  water,  renders  it  liable  to  be 
separated.    Jervina,  when  pure,  is  white,  easily  fusible,  de- 
composable at  400°,  nearly  insoluble  in  water,  but  copious- 
ly soluble  in  alcohol.     Of  its  salts,  the  acetate  readily  dis- 
solves in  water,  although  in  this  liquid  its  sulphate,  nitrate, 
and  chloride,  are  sparingly  soluble.     The  chloride  of  jer- 
vina  unites  with  chloroplatinic  acid.     Kane,  1069. 

Of  Colchicina,  or  Colchicine. 

5454.  Colchicina  is  a  vegeto-alkali  existing  in  the  seeds 
of  the  meadow  saffron  (Colchicum  autumnale). 

5455.  It  may  be  extricated  by  the  following  process. 
Digest  the  seeds  in  a  mixture  of  sulphuric  acid  and  weak 
alcohol;  neutralize  the  excess  of  acid  by  lime,  remove  the 
alcohol  by  distillation,  decompose  the  residual  liquor  by  car- 
bonate of  potash  in  excess,  dissolve  the  washed  and  dried 
precipitate  in  absolute  alcohol,  decolorize  the  solution  by 
animal  charcoal,  add  a  few  drops  of  water,  and  evaporate 
it  until  the  colchicina  crystallizes  in  colourless  needles. 

5456.  This  alkali  is  intensely  bitter,  but  not  so  biting  to 
the  taste  as  veratrine,  nor  is  it  productive  of  violent  sneez- 
ing.    It  is  moderately  soluble  in  water,  very  soluble  in  al- 
cohol, or  ether.    Though  but  feebly  alkaline  in  its  reaction, 
in  other  respects  it  neutralizes  acids  thoroughly.    By  tinc- 
ture of  iodine  it  is  precipitated  of  a  rich  orange  colour,  by 
nitric  acid  it  is  coloured  dark  violet  blue.     Though  most 
abundant  in  the  seeds,  it  pervades  all  parts  of  colchicum. 
Kane,  1069. 

Of  Emetia,  or  Emetine. 

5457.  This  alkali  is  obtained  from  ipecacuanha.     The 
roots,  well  pulverized,  are  digested  in  ether.     They  are 
then  subjected  to  alcohol,  the  resulting  solution  is  evapo- 
rated, and  the  residuum  dissolved  in  water,  and  macerated 
upon  magnesia,  which  causes  the  emetia  to  precipitate. 


OF  SOLANIA.  509 

This  precipitate  is  washed  with  cold  water  to  remove  co- 
louring matter,  and  afterwards  subjected  to  alcohol,  which 
takes  up  the  emetia.  The  emetine  again  separated  from 
its  solvent  by  evaporation,  being  dissolved  by  diluted  acid, 
and  blanched  by  animal  charcoal,  may  be  precipitated  pure 
by  any  of  the  alkaline  oxides. 

5458.  Thus  obtained,  emetia  is  white,  pulverulent,  and 
unalterable  by  the  air,  scarcely  soluble  in  water,  but  very 
soluble  in  ether  or  alcohol.     Its  taste  is  slightly  bitter.     It 
possesses  strong  alkaline  properties,  restoring  the  colour 
of  litmus,  when  reddened  by  an  acid.     It  is  capable  of 
forming  salts,  which,  though  neutral,  are  not  crystallizable. 
It  appears  to  possess  all  the  emetic  properties  of  the  root 
from  which  it  is  procured. 

Of  Solania,  or  Solanine. 

5459.  Solania  is  the  name  which  has  been  given  to  an 
alkali  which  exists  in  the  black  nightshade  (solanum  ni- 
grum),  and  in  the  bittersweet  (solanum  dulcamara),  also 
in  the  shoots  of  the  solanum  tuberosum,  or  potato. 

5460.  The  filtrated  juice  of  the  berries  of  the  nightshade 
being  digested  in  ammonia,  the  resulting  precipitate  is 
washed  on  the  filter,  and  digested  in  boiling  alcohol.    After 
the  evaporation  of  this  fluid,  solania  is  obtained  in  suffi- 
cient purity.     It  is  a  white,  opake,  pearly  powder,  which 
is  inodorous,  slightly  bitter,  and  nauseous.     Its  acid  solu- 
tions are  more  bitter.     Its  salts,  though  neutral,  are  un- 
crystallizable.     In  cold  water  it  is  insoluble,  and  in  hot 
dissolves  only  to  a  small  extent.    It  is  very  soluble  in  alco- 
hol, but  is  not  dissolved  by  ether.     It  restores  the  colour 
of  litmus,  reddened  by  an  acid.   It  causes  vomiting  at  first, 
afterwards  sleep,  or  death,  according  to  the  dose,  being  a 
strong  narcotic  poison.   With  salts  of  emetine,  tannic  acid, 
or  corrosive   sublimate,  it   produces  white   precipitates; 
with  iodine  and  chloroplatinic  acid,  brownish  yellow  preci- 
pitates.    According  to  Kane,  the  injurious  properties  of 
unripe  potatoes  result  from  the  presence  of  this  body.     It 
exists  abundantly  in  the  early  shoots  (underground)  and 
buds  of  the  tubers. 


510  ORGANIC  CHEMISTRY. 

Of  Caff  em  or  Caffeia*  or  Theine. 

5461.  It  seems  hardly  credible  that  there  should  be  a 
crystallized  nitrogenated  principle  common  both  to  tea  and 
to  coffee.     Yet,  agreeably  to  analyses  recently  made,  the 
substances  which  had  been  discovered  in  tea  and  coffee, 
and  called  theine,  or  caffein,  are  identical  in  composition 
and  properties. 

5462.  Moreover,  a  principle  elaborated  from  guarana, 
a  paste  made  from  the  seeds  of  paullinia  sorbilis,  is  alleged 
by  Martius  to  be  identical  in  composition  with  caffein,  and 
to  be  a  base  in  its  properties. 

5463.  To  extract  caffeia,  the  raw  coffee  seeds,  well  dried 
and  pulverized,  are  to  be  exhausted  by  boiling  water.     In 
the  next  place  subacetate  of  lead  must  be  added  to  the  re- 
sulting solution.     This  is  to  be  filtered  afterwards,   and 
any  excess  of  lead  precipitated  by  sulphydric  acid.     After 
a  second  filtration,  the  solution  being  concentrated  suffi- 
ciently by  evaporation,  the  caffeia  crystallizes  on  cooling. 
Re-solution,  and  recrystallization  are  requisite  to  render 
it  pure. 

5464.  Caffeia  may  also  be  extricated  from  a  filtered  de- 
coction of  tea  leaves :  hence  its  other  name,  theine. 

5465.  Caffeia  assumes  the  form  and  appearance  of  nee- 
dles, having  a  silky  lustre.     It  is  feebly  bitter,  sparingly 
soluble  in  ether,  cold  water,  or  alcohol.     At  212°  it  loses 
eight  per  cent,  of  water.    It  fuses  at  352°,  and  sublimes  at 
725°.    From  its  solution  it  may  be  thrown  down  by  tannic 
acid.     Boiled  with  caustic  potash,  or  baryta,  caffeia  is  re- 
solved into  ammonia,  cyanuric,  formic,  and  carbonic  acids. 
With  sulphuric  or  chlorohydric  acid  it  forms  crystalline 
compounds.     Its  composition,  according  to  Liebig,  is  re- 
presented by  the  formula  above  given. 

5466.  Graham  alleges  that  the  active  properties  of  tea 
and  coffee  are  not  due  to  caffeia;  but  it  is  admitted  that 
no  other  vegetable  substance  contains  so  large  a  propor- 

*  Caffeia  is  one  of  the  crystalline  organic  principles  which  it  is  difficult  to  name, 
or  to  classify,  on  account  of  the  discordancy  of  the  authorities  which  bear  upon  the 
question.  Heretofore  it  has  been  placed  among  the  neutral  principles,  and  in  the 
United  States  Dispensatory,  and  in  the  recent  works  of  Kane,  Graham,  and  Grego- 
ry, has  been  treated  of  as  such,  and  called  caffeia.  But  in  the  report  of  Berzelius 
for  1841,  it  is  mentioned  that  Martius  has  "  found  it  to  be  identical  with  guaranine," 
an  organic  base,  elaborated  from  the  seeds  of  paullinia  sorbilis.  Accordingly  it  is 
placed  by  Berzelius,  in  his  list  of  contents,  under  the  head  of  vegetable  bases,  with 
morphine,  brucia,  &e.  But  while  Martius  and  Berzelius  assign  to  it  the  rank  of  an 
alkali,  they  do  not  change  the  terminating  monosyllable,  as  the  continental  chemists 
have  not  adopted  the  termination  in  a  for  alkaline  bases. 


OF  CHELERYTHRINA.  511 


tion  of  nitrogen,  and  Liebig  remarks  that  2^  grains  of 
caflfeia  may  furnish  all  the  nitrogen  required  by  an  ounce 
of  human  bile.  This  fact  naturally  suggests  that  tea  and 
coffee  may  be  serviceable  in  furnishing  nitrogen  for  biliary 
and  other  secretions,  in  beings  whose  habits  of  life  do  not 
make  it  healthful  or  agreeable  to  consume  a  sufficient 
quantity  of  bread  and  meat  to  supply  all  the  nitrogen  ne- 
cessary to  the  vital  functions. 

5467.  According  to  this  view  of  the  subject,  it  is  re- 
markable, that  civilized  nations,  comprising  a  majority  of 
mankind,  should  in  modern  times  have  been  led,  as  it  would 
seem,  intuitively,  to  resort  to  two  sources,  apparently  so 
different,  as  the  tea  leaf  and  coffee  berry,  for  the  same 
preeminently  nitrogenated  principle  as  an  almost  indispen- 
sable article  of  daily  food. 

"  Chelerytkrina,  or  Chelerythrine. 

5468.  "This  substance  is  extracted  from  the  roots  of  the 
chelidonium  majus,  by  digestion  with  dilute  sulphuric  acid. 
The  liquor  so  obtained  is  to  be  evaporated  and  mixed  with 
ammonia.     The  brown  precipitate  which  falls   is  to  be 
washed,  pressed  between  folds  of  paper,  and  digested  in 
alcohol,  with  some  sulphuric  acid.     The  alcoholic  solution 
being  mixed  with  water,  and  the  spirit  distilled  off,  the  re- 
sidual liquor  is  precipitated  by  ammonia,  and  the  precipi- 
tate being  washed  and  dried  by  pressure,  is  to  be  digested 
in  ether,  and  the  ethereal  solution  evaporated  to  dryness. 
The  mass  so  obtained  is  then  digested  in  dilute  muriatic 
acid,  which  leaves  a  resinous  substance  undissolved.     The 
deep  red  liquor  evaporated  to  dryness,  and  washed  with 
ether,  leaves  a  mixture  of  muriate  of  chelerythrine  and 
muriate  of  cheledonine  ;  the  former  of  which  is  dissolved 
by  washing  with  a  small  quantity  of  water,  whilst  the  latter 
remains  undissolved." 

5469.  "From  the  solution  of  the  muriate,  the  cheleryth- 
rine is  precipitated  by  ammonia,  as  "a  white  curdy  powder. 
From  its  ethereal  solution  it  remains  as  a  resinous  mass, 
which  remains  soft  for  a  long  time  ;  it  is  insoluble  in  wa- 
ter; its  solutions  in  alcohol  and  ether  are  pale  yellow. 
With  acids  it  forms  salts  of  a  rich  crimson  colour,  which 
generally  crystallize.     Tannic  acid  produces  in  their  solu- 
tions a  precipitate  soluble  in  alcohol."     Verbatim  from 
Kane,  1070. 


512  ORGANIC  CHEMISTRY. 

"Chelidonia,  or  Chelidonine. 

5470.  "  The  preparation  of  this  substance  has  been  in 
great  part  described  in  the  preceding  article.     By  digest- 
ing the  sparingly  soluble  muriate  with  ammonia,  then  dis- 
solving in  sulphuric  acid  and  precipitating  with  muriatic 
acid,  it  is  freed  from  all  traces  of  chelerythrine,  and  finally 
the  pure  chelidonine,  separated  by  ammonia,  is  dissolved 
in  boiling  alcohol,  from  which  it  crystallizes,  on  cooling, 
in  brilliant  colourless  tables.     It  is  insoluble  in  water,  so- 
luble in  alcohol  and  ether;    it  tastes  bitter,  and  reacts 
alkaline ;  its  salts  are  colourless,  and  those  with  the  mine- 
ral acids  crystallize ;  its  solutions  give  with  tannic  acid 
a  precipitate."    Verbatim  from  Kane,  1071. 

Of  Atropia,  or  Atr opine. 

5471.  Atropia   is   procured  from  a  decoction   of  the 
leaves  of  the  Atropa  belladonna,  or  deadly  nightshade. 
Two  pounds  of  the  leaves  were  boiled  in  successive  por- 
tions of  water,  which  being  united,  and  sulphuric  acid 
added  to  the  whole,  the  resulting  liquid  was  filtered,  and 
yielded  a  crystalline  precipitate  with  potash.     This  preci- 
pitate, repeatedly  dissolved  in  acids,  and  precipitated  by 
alkalies,  gave  pure  atropia.     Thus  obtained,  it  is  snow- 
white,  and  quite  tasteless.     When  recently  precipitated,  it 
is  slightly  soluble  in  water.    After  being  dried,  it  is  insolu- 
ble in  water,  ether,  or  oil  of  turpentine.     In  cold  alcohol  it 
is  sparingly  soluble;  but  copiously  in  the  same  menstruum 
when  boiling  hot. 

5472.  Atropia  forms  compounds  with  acids,  which  can- 
not, however,  be  rendered  so  neutral,  as  not  to  indicate 
acidity. 

Of  Aconitia,  or  Aconitine. 

5473.  The  fresh  expressed  juice  of  the  monkhood,  aco- 
nitum  napellus,  being  boiled  and  filtered,  the  resulting  clear 
liquor,  subjected  to  an  excess  of  carbonate  of  potash,  is  to 
be  agitated  with  ether  so  long  as  it  takes  up  any  thing. 
On  vaporizing  the  ether,  aconitia  is  deposited.     From  the 
dry  plant,  or  its  seeds,  a  solution  of  aconitia  may  be  ob- 
tained by  water  holding  an  ounce  of  sulphuric  acid  for 
each  pound.     This  may  be  decomposed  by  carbonate  of 


OF  BELLADONIA  AND  DATURIA.  513 

soda,  and  the  alkali  extricated  from  the  resulting  precipi- 
tate by  ether  or  alcohol.  Aconitia  crystallizes  from  an 
etherial  or  alcoholic  solution,  partly  in  white  grains,  but 
for  the  most  part  forms  a  colourless  vitreous-looking  mass. 
It  has  a  sharp  bitter  taste,  and  is  intensely  poisonous.  It 
is  capable  of  neutralizing  the  most  powerful  acids.  Its  so- 
lutions give  a  white  precipitate  with  alkalies  proper,  or 
with  chloride  of  gold;  with  iodine  an  orange  precipitate. 

Of  Belladonia,  or  Belladonine. 

5474.  This  alkali  is  obtained  by  subjecting  the  dried 
root  of  belladonna  to  distillation  with  a  solution  of  caustic 
potash,  precipitating,  from  the  liquid  which  comes  over, 
the  alkali  with  which  it  is  accompanied,  by  chloroplatinic 
acid,  and  heating  the  washed  precipitate  with  carbonate 
of  potash.     The  belladonia  being  sublimed,  condenses  in 
colourless,   rectangular,   prismatic   crystals.      Belladonia, 
thus  isolated,  has  a  penetrating  odour  resembling  that  of 
ammonia,  and  forms  a  solution  with  water,  which  reacts 
like  that  of  an  alkali.     It  is  not  very  poisonous.     Its  salts 
are  much  like  the  corresponding  ammoniacal  salts. 

Of  Daturia,  or  Daturine. 

5475.  The  seeds  of  the  datura  stramonium,  vulgarly 
known  as  the  thorn  apple,  Jamestown,  or  jimson  weed, 
and  the  juice  of  the  leaves,  capsules,  and  stems,  contain 
the  alkaline  principle  to  which  the  name  at  the  head  of 
this  article  is  given.     It  is  to  this,  that  the  efficacy  of  the 
ointment  constituted  by  the  inspissated  juice,  and  the  well 
known  poisonous  property  of  the  plant,  are  due. 

5476.  Agreeably  to  the  process  of  Brandes,  who  first 
isolated  daturia,  the  seeds  are  to  be  boiled  in  alcohol,  and 
magnesia  being  added,  the  resulting  precipitate  is  to  be 
redissolved  by  the  same  liquid.     According  to  Kane,  it 
may  be  obtained  by  the  same  processes  as  aconitia,  above 
described. 

5477.  From  its  solution  in  spirit,  it  crystallizes  in  very 
brilliant  groups  of  needles.     It  is  quite  inodorous  when 
pure,  although  the  juice  of  the  plant  smells  disgustingly 
narcotic.     It  is  bitter,  and  tastes  somewhat  like  tobacco. 
For  its  solution,  it  requires  72  parts  of  boiling  water,  250 
of  cold  water,  21  parts  of  ether,  and  3  of  alcohol.    It  fuses 
below  212°,  and  at  a  higher  temperature  volatilizes,  un- 


514  ORGANIC  CHEMISTRY. 

changed,  in  white  clouds.  It  reacts  like  an  alkali,  and  is 
capable  of  forming,  with  acids,  crystallizable  salts,  which 
are  highly  poisonous.  In  its  habitudes  with  reagents,  it 
resembles  atropia. 

Of  Conina,  or  Coneine. 

5478.  This  alkali  exists  in  all  parts  of  the  hemlock  (co- 
mum  maculatum),  especially  in  the  seeds,  from  which  it 
may  be  extricated  by  the  following  means : — They  are  to 
be  bruised,  and  being  mingled  with  one  part  of  a  concen- 
trated solution  of  potash,  and  eight  of  water,  are  to  be  sub- 
jected to  the  distillatory  process  till  the  water,  which  dis- 
tils, becomes  inodorous.    The  distilled  solution,  after  being 
neutralized  by  sulphuric  acid,  must  be  evaporated  to  the 
consistency  of  a  syrup;  and  being,  in  this  state,  treated 
two  or  three  times  with  a  mixture  of  one  part  of  ether,  and 
two  of  alcohol  of  820°,  the  coneine  is  taken  up.     Some 
water  being  added,  the  ether  and  alcohol  are  removed  by 
distillation,  and  the  residual  water  by  evaporation.    The  de- 
siccated residuum  is  to  be  mingled  with  half  its  weight  of 
a  concentrated  solution  of  caustic  potash,  and  subjected  to 
distillation  with  a  receiver  carefully  refrigerated.    The  oily 
portion  must  be  separated  from  the  aqueous  portion  of  the 
liquid  which  comes  over,  and  this  last  again  distilled  from 
hydrate  of  lime.     From  any  ammonia  with  which  it  may 
be  associated,  the  coneine  may  be  freed  by  exposure  for  a 
few  hours  in  vacuo,  over  sulphuric  acid. 

5479.  Pure  coneine  is  extremely  poisonous,  existing  in 
the  form  of  a  colourless  transparent  liquid,  of  the  density  of 
.890.     Its  taste  is  disgustingly  sharp,  its  smell  highly  nau- 
seous and  pungent,  somewhat  like  that  of  the  plant.     It  is 
soluble  in  100  parts  of  cold  water,  which  becomes  turbid 
by  being  heated;  but  four  parts  of  coneine  dissolve  one  of 
water,  forming  a  solution  which  may  be  rendered  turbid 
by  the  heat  of  the  hand.     With  alcohol,  ether,  and  oils,  it 
mingles  in  all  proportions.     It  distils,  per  se,  at  370°,  but 
requires  less  heat  when  associated  with  the  steam  of  boil- 
ing water.     It  reacts  like  an  alkali  with  the  assistance  of 
water,  but  not  when  anhydrous.     It  is  capable  of  satu- 
rating acids  completely,  having  the  least  atomic  weight  of 
any  known  organic  alkali.     Its  salts,  which  crystallize  but 
imperfectly,  are  decomposed  by  much  water.     In  alcohol, 
or  a  mixture  of  this  solvent  with  ether,  they  readily  dis- 


OF  NICOTINA  OR  NICOTINE.  515 

solve,  but  are  insoluble  in  pure  ether.  The  precipitate 
given  by  their  aqueous  solutions  with  iodine  is  saffron  yel- 
low; that  yielded  with  tannic  acid,  white. 

5480.  Coneia  is  coloured  blood-red  by  nitric  acid.     By 
exposure  to  air  it  turns  brown,  and  is  resolved  into  ammo- 
nia, and  a  bitter,  inodorous,  resinous  substance,  which  is 
not  poisonous. 

Of  Nicotina  or  Nicotine. 

5481.  The  preceding  name  is  given  to  the  active  poi- 
sonous principle,  to  which  tobacco  (nicotiana  tobaccum) 
and  some  other  plants  owe  their  active  qualities.     For  its 
elaboration,  the  means  described  as  suitable  for  the  elabo- 
ration of  coneia  may  be  used,  though  in  either  case  mag- 
nesia, or  any  other  alkaline  earth,  or  alkali,  might  be  sub- 
stituted for  potash  in  the  first  step  of  the  process. 

5482.  Pure  nicotina  or  nicotine  is  a  colourless  oily  liquid, 
endowed,  in  a  high  degree,  with  the  odour  and  taste  of  to- 
bacco.    It  is  soluble  in  water  in  all  proportions,  which  is 
a  property  displayed  by  no  other  organic  base.     It  is  also 
soluble  in  ether  or  alcohol.     When  anhydrous,  it  emits 
white  fumes  at  212°,  and  at  480°  distils,  undergoing,  how- 
ever, a  partial  decomposition.     Its  distillation  is  accom- 
plished easily  with  the  aid  of  water. 

5483.  Nicotina  is  highly  alkaline,  neutralizing  and  form- 
ing soluble  salts  with  acids.     Of  these,  some  are  crystalli- 
zable,  retaining,  however,  the  savour  of  tobacco.     Sub- 
jected to  alkalies,  they  evolve  the  characteristic  odour  of 
the  plant.* 

5484.  Of  Lobelina  or  Lobeline. — It  appears  by  an  article 
in  the  American  Journal  of  Pharmacy  for  April,  1841,  Vol. 
13,  that  Mr.  Procter,  jr.,  has  obtained  an  organic  alkali 
from  the  seeds  of  the  lobelia  inflata,  by  acidulated  alcohol, 
displacement,  ether,  and  evaporation.    This  alkali  is  repre- 

/ 

*  A  new  process  for  the  evolution  of  nicotina  is  given  in  the  Journale  de  Pharma- 
cie,  for  February,  1842,  of  which  the  steps  are  as  follows  : — Maceration  for  24  hours 
in  water  acidulated  by  sulphuric  acid;  expression,  evaporation  to  a  syrupy  consist- 
ence; distillation  with  potash,  water  being  added  to  prevent  injurious  concentration; 
neutralization  by  oxalic  acid  ;  evaporation  to  dryness ;  treatment  with  absolute  alco- 
hol, which  takes  up  oxalate  of  nicotina;  evaporation,  decomposition  by  potash;  solu- 
tion in  ether;  evaporation,  whence  results  nicotina  free  from  all  impurity, excepting 
water  and  alcohol  in  a  minute  proportion.  Agreeably  to  M.  V.  Ortigosa,  the  author 
of  this  new  process,  nicotina  forms  compounds  with  chloroplatinic,  and  chlorohydrar- 
gyric  acid. 
66 


516  ORGANIC  CHEMISTRY. 

sented  as  having  a  great  resemblance  to  nicotina,  but  as 
much  less  poisonous. 

Picrotoxine  or  Picrotoxia. 

5485.  The  extremely  poisonous  principle  of  cocculus  in- 
dicus  has  received  the  name  of  picrotoxine,  but  has  not 
been  conceived  to  have  basic  properties,  nor  to  agree  with 
the  organic  alkalies  in  holding  nitrogen  as  an  element. 
Nevertheless,  in  the  late  work  of  Liebig  and  Gregory, 
1168,  it  is  arranged  among  the  organic  bases,  arid  is  al- 
leged to  have  been  shown,  by  the  recent  researches  of  Mr. 
Francis,  to  contain  1.38  per  cent,  of  nitrogen.    Yet  a  new 
formula  for  picrotoxine  had  not  been  published  by  that 
chemist. 

5486.  I  subjoin  an  account  of  the  process  for  obtaining 
this  alkali,  and  a  description  of  its  properties. 

5487.  The  bruised  cocculus  indicus,  after  being  sub- 
jected to  pressure  in  order  to  expel  as  much  as  possible  of 
their  fat  oil,  are  boiled  in  alcohol.     The  alcohol  being  se- 
parated from  the  matter  which  it  takes  up  by  distillation, 
this  matter  is  redissolved  in  boiling  water,  slightly  acidu- 
lated.    From  the  resulting  solution,  on  cooling,  the  picro- 
toxine separates  in  short,  thin,  colourless  prisms,  insuscep- 
tible of  fusion.     Picrotoxine  is  soluble  in  twenty-five  parts 
of  boiling  water,  and  very  soluble  in  alcohol.     It  is  in- 
tensely bitter,  and  highly  poisonous.     Its  formula  is  pro- 
bably C12  H7  O5N. 

Of  Antiarine  or  Antiaria. 

5488.  The  deadly  poison  to  which  the  name  of  antiarine 
has  been  given,  is  in  a  predicament  analogous  to  that  in 
which  picrotoxine  has  heretofore  been  placed.     I  mean 
that  of  resembling  many  of  the  organic  bases  in  its  acti- 
vity as  a  poison,  while  devoid  of  nitrogen,  and  of  the  abi- 
lity to  react  like  a  base.     It  is  not,  however,  improbable, 
that  further  researches  may  prove  the  pretensions  of  an- 
tiarine to  rank  with  the  organic  alkalies,  both  as  to  pro- 
perties and  composition.     Antiarine  is  the  active  principle 
of  that  most  deadly  upas  poison,  respecting  which,  highly 
exaggerated  accounts  were  published  about  forty  years 
ago,  representing  that  the  tree  producing  it  could  not, 
without  loss  of  life,  be  approached,  unless  upon  the  wind- 


BASES  FROM  THE  OIL  OF  MUSTARD.  517 

ward  side.  Its  formula  is  alleged  to  be  C12  H10  O5.  It 
crystallizes  in  small  scaly  crystals,  soluble  in  250  parts  of 
cold  water,  70  of  alcohol,  and  2790  of  ether. 

Bases  from  the  Oil  of  Mustard. 

5489.  Thiosinnamina. — When   the    oil   of  mustard  is 
brought  in  contact  with  three  or  four  times  its  volume  of 
strong  ammonia,  crystals  are  formed,  which  are  purified 
by  recrystallization.     These  are  thiosinnamina :  formula, 
C8  H8  N2  S2. 

5490.  Thiosinnamina  is  soluble  in  hot  water,  less  so  in 
cold  water,  soluble  in  alcohol  and  ether.     It  has  a  bitter 
taste,  and  no  smell.     At  392°  it  is  resolved  into  ammonia, 
and   a   resinoid  basic  compound   not   fully  investigated. 
Thiosinnamina  combines  with  acids,  but  its  salts  do  not 
crystallize:  it  yields  a  chloroplatinate  with  chloroplatinic 
acid  =  C8  H8  N2  S2  HC  Cl  +  Pt  Cl;  and  with  corrosive  sub- 
limate a  chlorohydrargyrate  =  C4  H4  NS  Cl  +  Hg  Cl. 

5491.  Sinnamina. — This  new  base  is  obtained  in  the  fol- 
lowing way: — Thiosinnamina  is  digested  with  moist  hy- 
drated  protoxide  of  lead  till  all  the  sulphur  is  removed. 
The  residue  is  then  subjected  to  water,  finally  to  alcohol. 
The  resulting  solution  is  evaporated  to  a  syrup,  which, 
after  some  time,  deposits  fine  transparent  crystals  of  sin- 
namina. 

5492.  Sinnamina  is  a  powerful  base,  expelling  ammonia 
from  its  salts,  and  precipitating  the  solutions  of  peroxide  of 
iron,  of  copper,  and  of  lead.     It  combines  with  acids,  but 
yields  no  crystallizable  salts.     It  is  precipitated  by  chloro- 
platinic and  chlorohydrargyric  acid,  and  throws  down  sil- 
ver from  its  solution  in  nitric  acid.     When   heated,   it 
evolves   ammonia,   and  leaves   a  basic   resinoid   matter. 
The  production  of  sinnamina  from  thiosinnamina  is  ef- 
fected by  the  separation  of  all  the  sulphur  with  more  or 
less  hydrogen.     I  say  more  or  less,  since  it  is  not  known 
with  certainty  whether  the  formula  of  sinnamina  is  C8  H6N2 
or  C4  H3  N2.     (Varrentrapp  and  Will.) 

5493.  Sinapolina. — This  compound,  discovered  by  Si- 
mon, is  obtained  by  depriving  oil  of  mustard  of  its  sul- 
phur, by  the  action  of  baryta  or  of  oxide  of  lead.     It  is 
soluble   in   hot   water   and   alcohol,    and   crystallizes   in 
shining,  fatty,  fusible  scales.     Its  solution  has  an  alkaline 
reaction.     It  combines  with  acids,  and  may  be  separated 


518  ORGANIC  CHEMISTRY. 

from  them  by  ammonia.  When  combined  with  chlorohy- 
dric  acid,  it  precipitates  the  chloroplatinic  and  chlorohy- 
drargyric  acids.  It  is  generated  from  the  oil  of  mustard 
by  the  abstraction  of  two  atoms  of  bisulphuret  of  carbon, 
and  the  addition  of  two  atoms  of  water.  Thus  C16  H10  N2 
S4  +  2HO  =  C14  H12  N2  O2  +  2CS2.  The  formula  of  sina- 
polina  is  C14  H12  N2  O2.  Liebig  and  Gregory,  1156. 

5494.  Cinchovine  is  the  name  given  by  Manzini  to  a  new  alkali  which 
he  has  extricated  from  a  species  of  Peruvian  bark,  "  cinchona  ovata."     It 
is  obtained  by  a  process  analogous  to  that  usually  employed  to  obtain  qui- 
nia.     No  statement  is  made  respecting  its  efficacy.     On  this  account,  and 
because  of  the  alleged  inefficacy  of  the  species  of  cinchona,  from  which  it 
is  derived,  it  may  be  inferred  that  cinchovine  has  little  or  no  practical  value, 
and  will  not  merit  that  more  should  be  said  of  it  here.     Comptes  Rendu, 
25,  125. 

5495.  Of  Cisampelina  or  Cisampeline,  also  called  pelosine.     In  his  Re- 
port on  Chemistry  for  1841,  Berzelius  gives  the  following  information  re- 
specting this  base,  lately  discovered  by  Wiggers.     A  filtered  solution  of  the 
roots  of  cisampelos  pareira,  obtained  by  digestion  in  water  acidulated  by 
sulphuric  acid,  is  saturated  with  carbonate  of  soda,  avoiding  to  add  an  ex- 
cess.    The  precipitate  twice  washed,  and  well  dried  by  filtering  paper,  and 
subsequent  exposure  to  a  heat  of  212°,  is  subjected  to  pure  ether.     Being 
taken  up  by  this  solvent,  it  is  recovered  from  it  pure  and  anhydrous  by  the 
distillatory  process. 

5496.  Cisampelina,  thus  procured,  is  hard  and  brittle,  and  to  the  taste, 
sweetish  bitter  and  nauseous.     It  has  not  been  crystallized.     It  is  to  this 
principle  that  the  medicinal  properties  of  the  cisampelos  pareira  are  as- 
cribed.    The  alkali  is  called  pelosine  by  Wiggers,  its  discoverer;  but  I 
concur  with  Berzelius,  that  the  other  appellation  is  preferable  as  recalling 
the  idea  of  its  source. 

5497.  Of  Hederina,  Surinamina,  and  Jamaicina. — In  1824,  Mr.  Hut- 
tenschmidt  alleged  that  he  had  discovered  two  bases  in  the  "cortex  geofFriae 
jamaicensis  and  surinamensis."     Agreeably  to  Berzelius'  report,  the  exist- 
ence of  these  bases  has  lately  been  confirmed  by  Wiggers.     Vandamme 
and  Chevalier,  according  to  the  same  authority,  have  discovered  a  base  in 
hedera  helix.     As  no  important  efficacy  is  ascribed  to  these  bases,  I  do  not 
deem  it  necessary  to  notice  them  further.     The  same  considerations  have 
prevented  me  from  noticing  some  other  bases,  of  which  accounts  are  to  be 
found  in  the  reports  of  the  great  Swedish  chemist;  and  likewise  melamine 
and  ammeline,  derived  from  melam,  a  product  of  the  decomposition  of  sul- 
phocyanide  of  potassium. 

Of  certain  general  characteristics  of  the  Vegetable  Alkalies  distinguish- 
ing them  from  Inorganic  Bases,  and  of  those  which  distinguish  them 
into  several  different  sets. 

5498.  It  is  observed  by  Liebig  and  Gregory,  that  the  organic  bases  re- 
quire less  acid  for  saturation  in  proportion  as  they  contain  more  oxygen; 
although  it  is  well  known,  that  the  more  the  oxygen  in  an  inorganic  base, 
the  greater  the  quantity  of  acid  which  its  saturation  requires. 


BASES  FROM  THE  OIL  OF  MUSTARD.  519 

5499.  Agreeably  to  the  same  authority,  the  salts  formed  with  aconita, 
atropia,  brucia,  cinchonia,  codeia,  conicina,  delphinina,  emetia,  morphia, 
narcotia,  quinia,  strychnia,  veralria,  are  precipitated  white  by  an  infusion 
of  galls.     The  precipitate  is  a  tannate,  which,  by  exposure  to  the  air,  be- 
comes converted  into  a  soluble  gallate.* 

5500.  I  will  here  quote  from  Liebig  and  Gregory  the  following  arrange- 
ment of  the  alkalies,  as  I  consider  such  generalization  always  instructive, 
and  serviceable  to  the  memory. 

1.  Volatile  bases  containing  no  oxygen. 

These  are  anilina  and  nicotina,  to  which  may  be  added  conicina,  although 
it  is  not  certain  that  this  base  is  destitute  of  oxygen. 

2.  Bases  derived  from  the  oil  of  mustard. 

These  are  thiosinnamina,  sinnamina,  and  sinapolina. 

3.  Bases  of  cinchona  bark. 

These  are  quinia,  cinchonia,  and  aricina. 

4.  Bases  of  the  papaveracece,  or  the  various  species  of  poppy. 

These  are  morphia,  codeia,  narcotina,  thebaina,  pseudomorphia,  narceia, 
and  chelidonia. 

5.  Bases  found  in  the  solanacece,  strychnacea,  and  other  plants  of  the 
same  kind. 

These  are  atropia,  solania,  jervina,  brucia,  strychnia,  sabadillia,  veratria, 
delphia,  staphisia,  menispermia,  picrotoxia,  emetia,  corydalina,  berbina,  pi- 
perina,  harmalina,  caffeia,  and  theobromia. 

5501.  I  have  pointed  out  the  inconsistency  of  supposing  (5406),  that 
when  chlorohydric  acid  combines  with  an  organic  alkali,  it  can  form  a 
combination  meriting  to  be  called  a  chlorohydrate,  while  the  compound 
which  is  engendered  by  the  contact  of  this  acid  with  ammonia  is  supposed 
to  be  ammonium;  in  other  words,  a  chloride  of  the  hydruret  of  that  gaseous 
body.     On  the  subject  of  iodine,  Berzelius  has  urged  that  "a  direct  combi- 
nation of  it  with  a  vegetable  alkali  is  as  unlikely  to  exist,  as  would  be  a 
like  combination  with  any  other  salifable  base;  and,  moreover,  experience 
shows,  that  such  compounds  are  neither  iodates,  nor  iodohydrates  of  the 
vegetable  alkali." 

5502.  It  must  be  evident,  that  whatever  objections  exist  to  assuming  the 
existence  of  iodohydrates  of  organic  bases,  apply  with  equal  force  to  the 
existence  of  chlorohydrates,  bromohyd rates,  fluohydrates,  &c.  &c. 

5503.  Agreeably  to  the  representations  of  Berzelius,  founded,  in  great 
measure,  on  the  investigations  of  Bouchardat,  the  vegetable  alkalies  have, 
in  common  with  ammonia,  a  propensity  to  combine  with  two  atoms  of  io- 
dine, the  recognised  combinations  consisting,  not  of  an  atom  of  iodine  and 
an  atom  of  the  vegetable  alkali,  but  of  a  compound  of  iodine  and  an  iodo- 
hydrate  of  such  an  alkali.     This  view  of  the  subject  is  alleged  to  be  cor- 
roborated by  the  fact,  that  the  combinations,  with  organic  bases  alluded  to, 
are  obtained,  with  pre-eminent  facility,  by  a  double  decomposition  conse- 
quent to  the  reaction  of  bi-iodide  of  potassium  with  a  salt  formed  by  an  acid 
with  one  of  these  alkalies.    The  precipitates  of  the  alkalies  in  question,  thus 
obtained,  are  nearly  insoluble,  and  in  many  instances  well  characterized. 
Hence  the  bi-iodide  of  potassium  may  be  more  confidently  relied  upon  as  a 
precipitant  of  the  organic  bases  than  tannic  acid.     From  the  precipitated 

*  This  does  not  altogether  confirm  the  allegation  quoted  from  O.  Henry  (5307, 
note),  that  tannic  acid  may  be  used  as  a  general  mean  of  precipitating,  and  thus  ob- 
taining the  vegetable  alkalies.  No  suggestion  is  made  as  to  any  advantageous  mer 
thod  of  extracting  the  alkali  from  the  precipitate. 


520  ORGANIC  CHEMISTRY. 

compound  of  iodine  with  the  organic  base,  the  latter  may  be  liberated  by 
subjecting  them  in  water  to  sulphydric  acid.  By  these  means  the  iodine  is 
converted  into  iodohydric  acid,  after  which,  an  inorganic  alkaline  base  will 
separate  the  organic  alkali  in  an  isolated  state.  Berzelius'  Report  for  1840, 
p.  179. 

5504.  It  may  be  proper  to  mention,  that  bi-iodide  of  potassium  is  formed 
by  digesting  iodine  in  a  solution  of  iodide  of  potassium,  usually  erroneously 
designated  in  the  shops  as  hydriodate  of  potash.     The  bi-iodide  can  only 
exist  in  solution,  according  to  Berzelius.* 

Constitution  of  the  Organic  Alkalies. 

5505.  All  the  organic  alkalies  are  constituted  of  hydro- 
gen, carbon,  oxygen,  and  nitrogen,  except  melamine,  nico- 
tina,  and  anihna,  which  are  devoid  of  oxygen. 

5506.  It  is  remarkable  that  these  alkalies  contain  a  very 

large  proportion  of  carbon,  and  that  in  all  of  them  nitro- 

t 

*  "Chloride  of  Gold  as  a  test  of  certain  Vegetable  JlUcalics.—MM.  Larocque  and 
Thibierge  find,  that  perchloride  of  gold  is  a  more  decisive  test  of  certain  vegetable 
alkalies,  than  the  double  chloride  of  sodium  and  gold  already  employed  for  this  pur- 
pose. The  following  are  the  colours  of  the  precipitates  which  it  produces  with  the 
salts  of  the  annexed  alkalies  dissolved  in  water: — Quinia,  buff-coloured;  cinchonia, 
sulphur-yellow ;  strychnia,  canary-yellow ;  veratria,  slightly  greenish-yellow ;  bru- 
cia. milk,  coffee,  and  then  chocolate-brown;  morphia,  yellow,  then  bluish,  and  lastly 
violet.  In  this  last  state  the  gold  being  reduced,  the  precipitate  is  insoluble  in  water, 
alcohol,  the  caustic  alkalies,  and  sulphuric,  nitric,  or  hydrochloric  acids;  but  forms 
with  aqua  regia  a  solution  which  is  precipitated  by  protosulphate  of  iron. 

"  All  these  precipitates,  with  the  exception  mentioned,  are  very  soluble  in  alcohol, 
insoluble  in  ether,  and  slightly  soluble  in  water.  They  appear  to  be  combinations  of 
gold,  chlorine,  and  the  vegetable  alkali,  since  their  alcoholic  solutions,  treated  with 
tannin,  give  a  greenish-blue  precipitate  of  reduced  gold  ;  if  the  solution  be  filtered, 
and  the  alcohol  be  evaporated  by  heat,  a  precipitate  of  tannate  of  the  alkali  employed 
is  formed.  The  liquor  again  filtered,  gives  with  nitrate  of  silver  a  white  precipitate 
insoluble  in  nitric  acid,  but  soluble  in  ammonia. 

"  Among  the  reactions  of  chloride  of  gold,  those  which  occur  with  morphia  and 
brucia,  to  the  authors  appear  to  be  especially  important,  as  they  are  sufficiently 
marked  to  prevent  these  alkalies  from  being  mistaken  for  each  other,  and  also  yield 
pretty  good  characteristics  for  distinguishing  brucia  from  strychnia. 

"  The  authors  have  also,  as  the  results  of  their  experiments,  arrived  at  the  follow- 
ing conclusions : — 

"  1st.  By  the  aid  of  reagents  it  is  possible  to  determine  the  presence  of  morphia, 
strychnia,  and  brucia,  in  substances,  which,  after  being  mixed  with  the  salts  of  these 
alkalies,  have  undergone  the  vinous,  acetic,  or  putrefactive  fermentation.  M.  Orfila 
has  already  shown  that  the  putrefactive  fermentation  does  not  alter  morphia. 

"2dly.  Crystallized  iodic  acid,  or  a  concentrated  solution  of  this  acid,  is  suscepti- 
ble of  being  decomposed  by  neutral  azotized  bodies;  but  a  dilute  solution  of  this  acid 
cannot  be  decomposed  by  them,  unless  there  be  added  concentrated  sulphuric  acid, 
crystallizable  acetic  acid,  oxalic,  citric,  or  tartaric  acid. 

"  3dly.  Iodic  acid  should  not  be  employed  as  a  test  of  morphia  without  the  greatest 
caution. 

"  4thly.  Perchloride  of  gold  produces  such  effects  with  the  vegetable  alkalies,  as 
serve  to  distinguish  morphia,  brucia,  and  strychnia,  from  each  other. 

"  Sthly.  The  reagents,  on  which  the  greatest  reliance  may  be  placed  as  tests  of 
morphia,  are  nitric  acid,  neutral  perchloride  of  iron,  and  perchloride  of  gold. 

"  Gthly.  By  the  use  of  reagents,  morphia,  which  has  been  mixed  with  beer,  soup, 
or  milk,  may  be  detected. 

"  7thly.  It  is  also  easy  to  prove,  by  reagents,  the  presence  of  meconic  acid  in  soup 
or  milk,  especially  when  the  meconate  of  lead  is  decomposed  by  dilute  sulphuric 
acid,"  Journal  de  Chimie  Medicale,  Octobre,  1842  (5265). 


OF  IMPORTANT  NEUTRAL  ORGANIC  PRINCIPLES.  521 

gen  is  likewise  a  constituent.  It  was  at  one  time  alleged, 
that  agreeably  to  the  analysis  of  Liebig,  in  an  equivalent 
of  any  of  the  alkalies  of  this  class,  only  one  atom  of  ni- 
trogen could  be  found;  but  subsequent  observation  has 
shown  that  this  rule  has  exceptions,  since  strychnia  and 
brucia  are  found  each  to  contain  two  atoms  of  the  element 
in  question ;  and  in  some  other  organic  bases,  the  propor- 
tion of  nitrogen  exceeds  that  of  an  atom  to  each  equiva- 
lent. 

5507.  As  morphia  differs  from  codeia  only  in  having 
one  atom  more  of  oxygen;  and  as  the  three  alkalies  of 
Peruvian  bark  differ  only  in  the  same  way;  quinia  having 
one  atom  of  oxygen  more  than  cinchonia,  and  aricina  one 
atom  more  than  quinia,  the  idea  has  been  suggested,  that 
in  either  case  a  compound  radical  may  exist,  capable  of 
different  degrees  of  oxidation :  hence  morphia  might  be  a 
bioxide,  and  codeia  a  protoxide,  of  the  same  radical;  and 
in  like  manner  cinchonia  might  be  a  protoxide,  quinia  a 
bioxide,  and  aricina  a  trioxide,  of  one  radical.     But  were 
such  the  case  when  presented  to  chlorohydric  acid,  these 
oxides  should  severally  have  their  basic  oxygen  replaced 
by  as  many  atoms  of  chlorine,  which  is  alleged  not  to  ar- 
rive when  the  experiment  is  tried.    They  all  form  muriates, 
so  called,  under  the  circumstances  alluded  to,  or  chloro- 
hydrurets,  agreeably  to  the  view  which  I  have  taken  re- 
specting their  composition  (5406).     See  Kane,  1078. 

OF  IMPORTANT  NEUTRAL  ORGANIC  PRINCIPLES. 

Of  Salicin,  a  neutral  Principle,  and  of  some  Compounds  de- 
rived from  it,  or  to  the  production  of  which  it  contributes. 

5508.  The  discovery  of  an  analogy,  if  not  an  identity, 
between  the  properties  of  the  oil  of  gaultheria,  and  that  of 
spirea  ulmaria,  induces  the  idea  that  there  may  be  essen- 
tial oils  in  other  vegetables  of  the  United  States,  which 
may  be   worthy  of  examination.     Under   these   circum- 
stances, every  fact  connected  with  the  origin  of  the  oil  of 
spirea  ulmaria,  must  be  interesting  to  the  lover  of  science. 
I  have,  therefore,  deemed  it  expedient  to  give  some  details 
respecting  salicin,  the  principle  from  which  the  artificial 
"  hydruret  of  salycyl,"  saliculous  acid,  is  extricated,  and 
likewise  of  some  substances  resulting  from  the  reaction  of 
salicine  with  other  bodies  (5321,  &c.). 


522  ORGANIC  CHEMISTRY. 

5509.  Salicin,  C42  H23  O16  +  6HO.  This  interesting 
principle,  discovered  by  Le  Roux  and  Buckner,  is  found 
in  the  bark  and  leaves  of  bitter  willows,  and  in  that  of 
some  species  of  poplar.  It  is  obtained  by  subjecting  the 
bark,  in  a  divided  state,  to  successive  portions  of  boil- 
ing water.  The  resulting  decoctions  being  united  and 
concentrated  by  further  ebullition,  are,  while  boiling,  min- 
gled with  litharge  gradually  added  until  the  liquor  be- 
comes colourless.  The  lead,  combining  with  the  salicin, 
may  be  precipitated  from  it,  together  with  various  im- 
purities, by  adding  sulphuric  acid  at  first,  and^  then  sul- 
phide of  barium.  With  the  aid  of  charcoal,  and  repeated 
crystallization,  the  salicin  is  obtained  finally  in  delicate, 
silky  white  transparent  needles,  permanent  in  the  air.  It 
is  bitter  and  inodorous,  but  without  any  reaction  with  ve- 
getable colours.  It  sustains  no  loss  of  weight  at  a  boiling 
heat,  but  at  a  higher  temperature  is  decomposed,  becoming 
yellow,  resinous,  evolving  inflammable  vapour,  and  finally 
leaving  a  carbonaceous  residue.  It  is  soluble  in  five  parts 
of  cool  water,  and  in  any  proportion  in  boiling  water.  It 
is  no  less  s'oluble  in  alcohol,  but  is  insoluble  in  ether,  or 
the  fixed  oils.  It  forms  with  concentrated  sulphuric  acid 
a  blood-red  solution,  which  is  blackened  when  heated. 
Any  bark  which  contains  salicin  is  liable  to  be  reddened 
by  contact  with  sulphuric  acid.  Salicin  is  thrown  down 
from  any  of  its  solutions  by  acetate  of  ammonia.  That 
saliculous  acid  is  evolved  by  distilling  salicin  with  sulphu- 
ric acid  and  bichromate  of  potash,  has  already  been  men- 
tioned (3066,  5320). 

5510.  Saliretine,  C30  H15  O7  +  HO,  is  a  resinous  substance  produced  by 
boiling  salicin  either  in  diluted  sulphuric,  or  chlorohydric,  acid.    It  is  soluble 
in  caustic  alkalies,  excepting  ammonia ;  likewise  in  alcohol  or  ether,  but  is 
insoluble  in  water.     By  sulphuric  acid  it  is  changed  to  a  blood-red ;  and  it 
seems  likely  that  it  is  to  the  generation  of  this  resin  that  the  reddening  of 
salicin  by  that  acid  is  due.     One  atom  of  hydrated  saliretine,  with  an  atom 
of  raisin  sugar,  comprise  the  elements  of  one  atom  of  hydrated  salicin. 

5511.  Chlorosalicine,  C42  H25  Cl4  O22.    When  a  solution  of  salicine  is  im- 
pregnated with  chlorine,  a  crystalline  deposition  ensues,  which  dissolves  in 
water  with  difficulty,  but  in  hot  alcohol  with  ease.    It  may  be  considered  as 
comprising  the  same  elements  as  salicin,  excepting  the  substitution  of  four 
atoms  of  chlorine  for  a  like  number  of  hydrogen. 

5512.  When  during  the  impregnation,  in  the  process  above  described, 
the  temperature  is  raised  to  140°,  a  compound  is  obtained  in  which  seven 
atoms  of  hydrogen  have  been  replaced  bv  a  like  number  of  chlorine ;  for- 
mula C42  H18  Cl7  O18. 


OP  IMPORTANT  NEUTRAL  ORGANIC  PRINCIPLES.  523 

5513.  Rutiline.  Under  this  appellation  Braconnot  designates  a  substance 
arising  from  the  decomposition  of  salicine  by  concentrated  sulphuric  acid. 
Pure  rutiline,  when  moist,  appears  at  first  reddish-brown,  but  soon  becomes 
yellow ;  when  desiccated,  its  colour  is  brownish-black.     It  is  friable,  insi- 
pid, inodorous,  and  insoluble  in  water  or  alcohol.     By  inorganic  acids  its 
hue  is  changed  to  a  beautiful  red,  by  alkalies  to  a  deep  violet. 

5514.  Phloridzine,  C43  H33  O18  +  6HO.    The  preceding  name  has  been 
given  to  a  principle  discovered  by  De  Koninck  in  the  bark  of  the  roots  of 
apple,  pear,  cherry,  and  plum  trees.     In  composition  and  properties  it  is 
very  analogous  to  salicin ;  and  differs,  as  respects  elementary  constituents, 
only  in  having  two  more  atoms  of  oxygen.     Phloridzine  is  extracted  from 
any  bark  in  which  it  may  exist,  by  boiling  alcohol  of  the  specific  gravity  of 
.850.     From  the  alcoholic  solution  thus  obtained,  it  crystallizes  on  the  re- 
moval of  the  solvent  in  delicate,  colourless,  silky,  rectangular,  prismatic 
needles;  which  are  soluble  in  1000  parts  of  cold  water,  and  in  every  pro- 
portion in  boiling  water.     The  solution  has  an  astringent,  bitter  savour, 
without  any  power  to  change  vegetable  colours.     In  alcohol  it  is  also-  solu- 
ble, but  is  insoluble  in  ether.     At  212°  it  loses  four  atoms  of  water  of  crys- 
tallization.    It  melts  at  320°,  but  is  not  decomposed  under  390°. 

5515.  Phloridzeine,  C43  H29  O38  N2.     This  name  is  employed  to  desig- 
nate a  substance  obtained  by  the  reaction  of  phloridzine  with  ammonia  and 
atmospheric  oxygen.     As  its  name  differs  from  that  of  this  last  mentioned 
substance  only  in  the  presence  of  an  additional  e,  and  conveys  no  idea  of 
its  composition,  it  seems  very  ill  chosen.     By  simultaneous  contact  with  at- 
mospheric oxygen  and  gaseous  ammonia,  moist  phloridzirce  is  transformed 
into  a  red  matter,  which,  readily  dissolving  in  liquid  ammonia,  may  be  pre- 
cipitated therefrom  by  acids.     The  precipitate,  thus  obtained,  is  phlorid- 
zeine.     It  is  formed  by  the  addition  of  eight  atoms  of  oxygen,  and  the  ele- 
ments of  two  atoms  of  ammonia,  to  phloridziwe.     An  ammoniacal  solution 
of  phloridzeine,  evaporated  within  an  exhausted  receiver,  including  some 
fragments  of  the  hydrate  of  potassa,  is  converted  into  a  purple  blue  resi- 
duum, having  a  cupreous  metallic  brilliancy.    This  residuum  is  unalterable 
in  dry  air,  soluble  in  cold  water,  to  which  it  communicates  a  magnificent 
purple  blue.     This  solution  is  decolorized  by  deoxidizing  substances,  but 
resumes  the  oxygen  thus  lost,  and  the  blue  colour,  on  being  re-exposed  to 
the  air.     This  blue  residuum  is  compounded  of  an  atom  of  phloridzeine, 
and  an  atom  of  ammonia. 

5516.  Asparagine,  asparamide,  altheine,  agedoile. — These  are  the  syno- 
nymous appellations  of  a  principle  capable  of  forming  a  crystalline  hydrate, 
C8  H8  O3  N3  +  2HO,  which  loses  its  water  of  crystallization  at  248°.     It 
is  found  in  asparagus,  in  liquorice,  in  the  root  of  althea  officinalis,  in  that  of 
the  potato,  and  various  other  plants.     It  crystallizes  in  large,  transparent, 
right  rhombic  prisms.     It  has  a  cooling  and  somewhat  nauseous  taste,  is 
soluble  in  water  and  diluted  alcohol,  but  insoluble  in  this  last  mentioned 
liquid  when  concentrated,  or  in  ether.     By  reaction  with  acids  or  alkalies, 
assisted  by  heat,  asparagine  is  resolved  into  ammonia,  and  an  acid  called 
aspartic.     The  considerations  which  were  mentioned  as  giving  importance 
to  caffein,  must  apply  to  asparagine  as  being  a  highly  nitrogenated  princi- 
ple, since  such  principles,  without  any  very  sensible  activity,  may,  agree- 
ably to  the  suggestions  of  Liebig,  be  of  importance  in  supplying  the  nitro- 
gen requisite  to  facilitate  the  functions  of  life. 

5517.  Taraxacine. — Mons.  Polex  has  extracted  from  the  milky  juice  of 
the  leontodon  taraxacum,  a  crystallizable  substance,  which  he  has  named 

67 


524  ORGANIC  CHEMISTRY. 

taraxacine.  The  milky  juice  of  the  plant  is  boiled  in  distilled  water,  by 
which  means  the  albumen  is  coagulated,  involving  the  resin,  fatty  matter, 
and  caoutchouc.  The  concentrated  liquor  is  filtered,  and  allowed  to  evapo- 
rate spontaneously  in  a  place  moderately  warm.  The  taraxacine  crystal- 
lizes during  this  operation,  and  may  be  afterwards  purified  by  repeated 
crystallizations  from  alcohol  or  water.  It  forms  arborescent  or  star-shaped 
crystals.  These  melt  readily,  are  not  volatile,  and  have  a  bitter  and  rather 
acrid  taste.  They  are  sparingly  soluble  in  cold  water,  but  dissolve  abun- 
dantly in  boiling  water,  in  alcohol,  or  ether.  They  dissolve  in  the  con- 
centrated acids  without  being  decomposed.  Taraxacine  contains  no  nitro- 
gen. 

5518.  When  the  albuminous  precipitate,  which  has  been  separated  from 
the  water,  is  boiled  in  alcohol,  a  colourless  substance,  in  the  form  of  small 
cauliflower  crystals,  is  obtained  on  the  evaporation  of  the  alcohol.     On 
being  dried  it  falls  into  a  powder,  very  fusible,  but  difficult  to  be  ignited. 
It  is  insoluble  in  water,  but  very  soluble  in  alcohol  and  ether.     The  solu- 
tion has  an  acid  taste,  and  yields  no  precipitate  with  acetate  of  lead.     It 
is  insoluble  in  the  caustic  alkalies.     Berzelius'  Report  on  the  Progress  of 
Science. 

Of  certain  Vegetable  Principles  devoid  of  Nitrogen. 

5519.  I  have  quoted  verbatim,  from  Gregory  and  Liebig's  new  edition  of 
Turner's  Chemistry,  1118,  the  following  account  of  vegetable  principles  de- 
scribed as  devoid  of  nitrogen,  and  of  a  nature  not  yet  fully  ascertained; 
in  hopes  that  some  of  my  pupils  may  be  induced,  by  their  investigations,  to 
endeavour  to  remedy  the  imperfection  in  chemical  science  thus  admitted  to 
exist. 

5520.  "  Gentianine. — Extracted  by  ether  from  the  root  of  Gentiana 
lutea,  and  purified  by  solution  in  alcohol.     It  forms  golden  yellow  crystals, 
of  a  very  bitter  taste,  which  may  be  sublimed.    According  to  TrommsdorfF, 
when  quite  pure  it  is  no  longer  bitter,  and  has  acid  properties,  expelling  car- 
bonic acid  from  the  alkaline  carbonates,  and  forming,  with  the  alkalies, 
golden-yellow  crystallizable  salts. 

55:21.  "  Santonine  is  found  in  the  flowers  of  several  species  of  Arte- 
misia, and  in  the  so  called  Semen  Cyncz,  which  is  much  used  as  a  ver- 
mifuge, and  is  a  mixture  of  the  flowers,  buds,  and  unripe  seeds  of  these 
plants.  Four  parts  of  this  mixture  are  digested  with  one-half  of  slaked 
lime  and  twenty  of  alcohol,  at  90  per  cent.  The  santonine  is  dissolved,  in 
combination  with  lime  and  with  a  brown  resin.  It  is  separated  by  acetic 
acid,  but  is  still  contaminated  with  resin.  This  is  removed  by  washing 
with  a  little  alcohol;  and  the  residue  being  dissolved  in  eight  or  ten  parts  of 
alcohol  at  eighty  per  cent.,  and  boiled  with  animal  charcoal,  the  liquid,  on 
cooling,  deposits  santonine  in  colourless  crystals,  which  must  be  kept  in  the 
dark,  as  they  become  yellow  when  exposed  to  light.  It  is  tasteless  and  in- 
odorous, fusible  and  volatilizable,  sparingly  soluble  in  water,  more  easily  in 
alcohol  and  ether.  It  has  acid  properties,  and  forms  salts  with  potash  and 
soda,  the  latter  of  which  crystallizes.  Acids  dissolve  it  without  altering  it, 
and  water  precipitates  from  the  solution  the  santonine  unchanged.  It  forms 
crystalline  salts  with  lime  and  baryta,  and  insoluble  compounds  with  many 
metallic  oxides.  Its  composition  is  represented  by  the  formula  CSH3O 
(Ettling);  but  its  atomic  weight  must  be  twelve  times  greater,  to  judge  from 
its  capacity  of  saturation. 


OF  VEGETABLE  PRINCIPLES  DEVOID  OF  NITROGEN.         525 

5522.  "  Picrolichenine. — Discovered  by  Alms  in  the  lichen  Vuriolaria 
amara,  from  which  it  is  extracted  by  alcohol.     It  is  purified  from  a  green 
matter  which  accompanies  it,  by  washing  with  a  dilute  solution  of  carbonate 
of  potash.     It  forms  obtuse  double  four-sided  pyramids,  which  have  a  most 
intense  bitter  taste.     When  acted  on  by  ammonia  in  a  close  vessel,  it  dis- 
solves; and  after  some  time  the  solution  becomes  yellow,  and  deposits  yel- 
low crystals,  which  are  not  bitter.     When  the  arnmoniacal  solution  is  ex- 
posed to  the  air,  a  dark  red  substance  is  formed,  which  indicates  an  analogy 
between  this  substance  and  orcine,  which,  as  will  be  hereafter  mentioned, 
occurs  in  other  lichens.     Its  composition  is  unknown,  but  it  contains  no  ni- 
trogen.    It  is  said  to  be  powerfully  febrifuge. 

5523.  "  Cetrarine  is  analogous  to  the  preceding.     It  occurs  in  several 
lichens,  as  in  Iceland  moss,  Cetraria  Islandica,  and  in  Sticta  pvlmonacea. 
It  is  extracted  by  alcohol.     It  forms  a  fine  white  powder,  very  bitter  to  the 
taste.     Concentrated  hydrochloric  acid  colours  it  deep  blue.     Its  other  pro- 
perties are  little  known,  but  it  is  said  to  be  used  as  a  febrifuge  in  Italy. 

5524.  "Elattrine  is  the  active  principle  of  elaterium,  the  inspissated 
juice  of  the  fruit  of  Momordica  elaterium.     The  elaterium  is  dissolved  in 
hot  alcohol,  and  the  concentrated  solution  thrown  into  water,  which  precipi- 
tates the  elaterine.    By  repeating  this  process  it  is  obtained  pure.  (Morries.) 
It  forms  delicate  silky  crystals  of  a  very  bitter  taste.     One-sixteenth  of  a 
grain  acts  as  a  drastic  purgative.     Its  composition  is  unknown.     It  merits 
a  more  minute  examination. 

5525.  "  Colocynthine. — The  bitter  and  purgative  principle  of  colocynth, 
which  is  the  pulp  surrounding  the  seeds  of  Cucumis  colocynthis.     It  is  ob- 
tained by  evaporating  the  infusion  made  with  cold  water,  at  first  in  oily 
drops,  which  afterwards  solidify  into  a  brown,  brittle  mass.     It  is  soluble 
in  water,  alcohol  and  ether,  intensely  bitter,  and  acts  as  a  drastic  purga- 
tive.    Its  chemical  characters  are  imperfectly  known,  and  it  is  probably  a 
mixture. 

5526.  "  Byronine. — Obtained  by  a  somewhat  similar  process  from  the 
juice  of  the  root  of  Byronia  alba  and  B.  dioica.     It  forms  a  brown  or  yel- 
lowish-white mass,  having  a  taste  at  first  sweetish,  then  acrid  and  very  bit- 
ter; soluble  in  water  and  alcohol,  insoluble  in  ether.     It  appears  to  contain 
nitrogen,  and  is  probably  a  mixture  of  several  compounds.     It  is  a  drastic 
purgative,  and  has  poisonous  properties. 

5527.  "  Mudarine  is  found  in  the  bark  of  the  root  of  Calotropis  Mu- 
darii.  (Duncan.)     It  is  soluble  in  water  and  alcohol.     The  aqueous  solu- 
tion gelatinises  when  heated  to  95°;  at  a  higher  temperature  it  is  coagu- 
lated, the  mudarine  separating  as  a  viscid  mass.     On  cooling,  it  is  slowly 
but  completely  redissolved.     Mudarine  has  powerful  emetic  properties. 

5528.  "  Scillitine. — Obtained  from  the  juice  of  squills,  the  bulb  of  Scilla 
maritima.     A  brittle  mass,  of  a  nauseous  bitter  taste.     It  acts  as  an  emetic 
and  as  a  purgative,  and  appears  to  be  poisonous.  (Tilloy.) 

5529.  "  Cathartine. — Similar  to  the  preceding.    Obtained  from  the  leaves 
of  Cassia  Senna  and  C.  lanceolata,  and  from  some  other  plants.     It  has  a 
bitter  nauseous  taste,  and  purgative  properties. 

5530.  "Xanthopicrine  is  found  in  the  bark  of  Xanihoxylum  Clava  Her- 
culis.     It  forms  greenish- yellow  silky  crystals,  intensely  bitter  and  astrin- 
gent.   It  is  very  soluble  in  alcohol,  and  has  neither  an  acid  nor  an  alkaline 
reaction.     Its  action  on  the  system  has  not  been  studied,  but  the  bark  is 
used  as  a  remedy  in  the  Antilles. 


526  ORGANIC  CHEMISTRY. 

5531.  "  Columbine. — Obtained  from  columbo,  the  root  of  Menispermum 
palmatum.     It  is  extracted  by  alcohol  or  ether.     Forms  colourless  and 
transparent  oblique  rhombic  prisms,  or  delicate  white  needles:  is  neutral, 
fusible,  and  contains  no  nitrogen.     It  is  very  bitter,  and  becomes  still  more 
so  when  dissolved  in  acetic  acid.     It  is  the  active  principle  of  columbo. 
(Wittstock.) 

5532.  "  Quassiine  is  the  bitter  principle  of  the  wood  of  Quassia  amara. 
When  pure,  it  forms  small  white  opaque  prisms,  which  are  intensely  bitter, 
and  very  soluble  in  alcohol.     From  the  analysis  of  Wiggers,  its  formula  is 
probably  C20  H12  O6. 

5533.  "  Lupuline  is  the  bitter  principle  of  hops,  the  female  flowers  of 
Humulus  lupulus.     It  is  neutral,  uncrystallizable,  soluble  in  water  and  al- 
cohol, and  very  bitter. 

5534.  "  Lactucine  is  the  active  principle  of  Lactucarium,  the  inspissated 
juice  of  Lactuca  sativa,  L.  wrosa,  and  L.  scariola.     It  forms  yellowish 
indistinct  crystals,  which  have  a  strong  persistent,  bitter  taste.     It  is  spa- 
ringly soluble  in  water,  very  soluble  in  alcohol.     The  anodyne  effects  of 
lactucarium  are  most  probably  to  be  ascribed  to  lactucine. 

5535.  "Ergotine. — Discovered  by  Wiggers  in  the  ergot  of  rye,  Secale 
cornutum.     It  is  obtained  as  a  brown  powder,  of  a  pungent  and  bitter  taste, 
and  is  conceived  by  Wiggers  to  be  the  active  principle.     He  describes  it  as 
narcotic  and  poisonous;  but  its  composition  and  properties  are  unknown, 
and  it  is  most  probably  a  mixture. 

5536.  "  Porphyroxine. — Discovered   by   Merck  in   Bengal  opium.     It 
forms  small  brilliant  crystals,  which,  when  dissolved  in  diluted  mineral 
acids  and  heated,  yield  a  red  colour.     It  is  neutral,  soluble  in  alcohol  and 
ether,  insoluble  in  water.    It  is  quite  distinct  from  the  other  crystalline  sub- 
stances found  in  opium,  but  as  yet  has  been  but  little  examined. 

5537.  "  Saponine  is  found  in  the  root  of  Saponaria  ojficinalis  and  Gyp~ 
sophila  Struthium.     It  is  extracted  by  alcohol,  and  purified  by  repeated 
crystallization  from  that  solvent.     It  forms  a  white  brittle  mass,  not  crys- 
tallizable.    It  has  a  taste  at  first  sweetish,  then  acrid  and  irritating;  and  the 
smallest  quantity  of  the  powder  introduced  into  the  nostril  causes  violent 
sneezing.     It  is  soluble  in  water;  and  the  solution,  even  when  very  dilute, 
froths  like  a  solution  of  soap.     The  root  is  used  as  a  detergent. 

5538.  "  Smilacine  :  Syn.  Parilline,  Salseparine. — Extracted  by  alco- 
hol from  Sarsaparilla  (Smilax  sarsaparilla).    It  is  crystallizable,  soluble 
in  hot  water  and  alcohol,  colourless  and  tasteless.     Its  solutions  have  the 
property  of  frothing.     Its  formula  appears  to  be  C15  H13  O5.     (Poggiale; 
Thubffiuf;  Petersen.)     The  Chinova  bitter  of  Winkler,  found  in  China 
nova,  has  been  shown  by  Buchner,  jun.,  to  be  identical  in  its  properties  with 
smilacine;  and  Petersen  has  shown  that  its  formula  is  C15  H13  O4,  differing 
from  that  of  smilacine  only  by  1  eq.  of  water. 

5539.  "Senegine:    Syn.   Polygaline,  Polygalic  Acid. — Is  found  in 
Polygala  senega  and  P.  virginea.     It  is  a  white  powder,  at  first  tasteless, 
afterwards  very  acrid,  and  causing  a  feeling  of  astringency  in  the  gullet. 
It  also  acts  as  a  sternutatory.     According  to  Quevenne,  its  formula  is 
C11  H18  O11. 

5540.  "Guaiacine. — Discovered  by  Trommsdorff  in  the  wood  and  bark 
of  Guaiacum  officinale.     It  forms  a  yellow  brittle  mass,  which  has  a  sharp 
acrid  taste.     It  is  no  doubt  one  of  the  active  principles  of  the  gum-resin  of 
guaiacum,  and  is  the  cause  of  its  acrid  taste. 

5541.  «« Plumbagine  occurs  in  the  root  of  Plumbago  Europcea.     It  is 


OP  VEGETABLE  PRINCIPLES  DEVOID  OF  NITROGEN.         527 

extracted  by  ether,  and  forms  fine  orange-yellow  crystals,  which  at  first 
have  a  sweet  taste,  followed  by  a  burning  acrid  sensation.  It  is  neutral, 
and  soluble  in  hot  water.  Alkalies  give  to  its  solution  a  cherry-red  colour, 
but  acids  restore  the  yellow.  The  root  also  contains  a  peculiar  fat,  not  yet 
investigated,  which  gives  to  the  skin  a  lead-gray  colour,  whence  the  name 
of  the  plant  is  derived. 

5542.  "Cyclamine:  Syn.  Arthanitine. — Found  in  the  root  of  Cycla- 
men Europaum.     It  crystallizes  in  fine  white  needles,  of  a  burning  acrid 
taste,  and  having  emetic  and  purgative  properties. 

5543.  "  Peucedanine. — Discovered  by  Schlatter  in  the  root  of  Peuceda- 
num  officinale.     Extracted  by  alcohol.     It  forms  delicate  white  prisms,  fu- 
sible, insoluble  in  water,  soluble  in  alcohol  and  ether.     The  solution  has 
an  acrid  burning  taste.     It  is  neutral.     Formula,  C4  H2  O.     In  some  roots 
that  had  long  been  kept,  Erdmann  found  a  modification  of  peucedanine,  dif- 
fering from  it  only  in  being  insoluble  in  ether.     Its  formula  was  C8  H4  O3; 
which  only  contains  one  atom  of  oxygen  more  than  the  formula  of  peuce- 
danine doubled,  and  was,  therefore,  probably  formed  from  it  by  the  action 
of  the  atmosphere. 

5544.  "  Imperatorine. — Found  by  Osann  in  the  root  of  Imperatoria  Os- 
trutium.     Is  extracted  by  ether.     It  forms  long  transparent  prisms,  has  an 
acrid  burning  taste,  is  neutral,  fusible,  insoluble  in  water,  soluble  in  alcohol 
and  ether.     Formula,  C24  H13  O5.  .  (F.  Drebereiner.) 

5545.  "  Tanghinine. — Extracted  by  ether  from  the  seeds  of  Tanghinia 
Madagascariensis  after  the  fixed  oil  has  been  removed  by  pressure.     It  is 
crystallizable;  soluble  in  water,  alcohol,  and  ether;  very  bitter  and  acrid. 
It  is  also  poisonous.     (Henry  and  Ollivier.) 

5546.  "  Meconine. — Discovered  by  Couerbe  in  opium.     It  is  dissolved, 
along  with  most  of  the  other  ingredients  of  opium,  when  water  is  used  as 
the  solvent ;  and,  being  soluble  in  water,  it  remains  dissolved  when  mor- 
phia, narcotine,  &c.,  are  precipitated  by  ammonia.     Part  of  it,  however, 
falls  along  with  the  precipitate.     It  is  purified  by  the  alternate  action  of  al- 
cohol, water,  and  ether;  in  all  of  which  it  is  soluble  with  the  aid  of  heat. 
When  pure,  it  forms  fine  white  prisms,  which  are  at  first  tasteless,  after- 
wards acrid.     It  is  fusible,  and  may  be  sublimed  unchanged.     It  requires 
for  solution  266  parts  of  cold  water,  and  18  parts  of  boiling  water.     When 
heated  with  water,  it  first  melts  into  an  oily  fluid,  and  gradually  dissolves. 
Sulphuric  acid,  diluted  with  half  its  weight  of  water,  dissolves  meconine, 
forming  a  colourless  solution,  which,  when  heated,  becomes  dark  green. 
Water  throws  down  from  the  green  solution  brown  flocks,  which  dissolve 
in  alcohol  with  a  rose-red  colour.     From  this  alcoholic  solution  the  salts  of 
alumina,  lead,  and  tin,  throw  down  fine  red  lakes.     Meconine  is  quite  neu- 
tral.    Its  formula,  according  to  Couerbe,  is  C10  H5  O4,  or  rather  the  half  of 
this;  but  its  composition  cannot  be  considered  as  ascertained.     By  the  ac- 
tion of  chlorine  it  is  converted  into  mechloic  acid,  and  nitric  acid  changes  it 
into  nitro-meconic  acid. 

5547.  "  Cubebine. — Found  by  Soubeiran  and  Capitaine  in  cubebs  pep- 
per (the  seeds  of  Piper  Cubeba).     It  is  neutral,  crystallizable,  tasteless, 
sparingly  soluble  in  water   and   alcohol.     Its   formula   is   probably  C34 
H17  O10. 

5548.  "  The  following  substances  are  neutral,  have  generally  a  bitter 
taste  or  are  tasteless,  and  are  to  a  certain  extent  problematical,  as  the  ob- 
servations regarding  them  are  very  imperfect.     It  is  probable  that  many  of 
them  will  be  found  identical  with  some  of  the  preceding. 


528  ORGANIC  CHEMISTRY. 

"Alcornine,  from  Alcornico,  the  root  of  Hedwigia  mrgelioides. 
"Alismine,  from  Alisma  Plantago. 
"  Arnicine,  from  Arnica  montana. 
"  Asclepine,  from  the  root  of  Asclepias  gigantea. 
"  Absinthiine,  from  the  flowers  of  wormwood,  Artemisia  absinthium. 
"  Antiarine,  from  Antiaris  toxicaria. 

"  Amanitine,  from  Agaricus  muscarius,  A.  bulbosus,  and  others. 
"  Buenine,  from  the  bark  of  Buena  hexandra. 
"  Canelline,  from  the  bark  of  Canella  alba. 
"  Cascarilline,  from  the  bark  of  Croton  Eleutheria. 
"  Cassiine,  from  Cassia  fistula. 
"  Centaurine,  from  Erythrtea  Centaurium. 
"  Colletine,  from  Colletia  spinosa. 
"  Coriarine,  from  Coriaria  myrtifolia. 
"  Cornine,  from  the  bark  of  the  root  of  Cornus  Jlorida. 
"  Corticine,  from  the  bark  of  Populus  tremula. 
"  Cytisine,  from  the  seeds  of  Cyiisus  Laburnum. 

"  Daphnine,  from  the  bark  of  Daphne  Mezereum  and  other  species.     It 
is  crystallizable. 

"Datiscine,  from  Datisca  cannabina. 

"Diosmine,  from  the  leaves  of  Diosma  crenata. 

"Euonymine,  from  the  seeds  of  Euonymus  Europ&us. 

"  Fagine,  from  Fagus  sylvatica. 

"  Fraxinine,  from  the  bark  of  Fraxinus  excelsior. 

"  Geraniine,  from  the  Geraniacece. 

"  Granatine,  from  unripe  Pomegranates. 

"  Guacine,  from  Guaco  leaves. 

"  Hesperidine,  from  the  spongy  part  of  the  Orange  rind.     Crystallizes. 

"Hyssopine,  from  Hyssopus  officinalis. 

"IHcine,  from  7/ea;  aquifolium.     Crystallizable. 

"Lapathine,  from  Rumex  obtusifolius. 

"  Ligustrine,  from  the  bark  of  Ligustrum  vulgare. 

"  Lilacine,  from  Syringa  or  Lilac. 

"  Liriodcndrine,  from  the  bark  of  the  root  of  Liriodendron  tulipifera. 

"  Me.nyanthine,  from  Menyanthes  trifoliata. 

*'  Melampyrine,  from  Melampyrum  nemorosum. 

"  Narcitine,  from  Narcissus  pseudo-narcissus. 

"  Olivile,  from  OZea  Europ&a. 

"  Olivine,  from  the  leaves  of  O/ea  EuroptBa. 

"  Primuline,  from  the  root  of  Primula  veris. 

"  Pyrethrine,  from  the  root  of  Anthemis  Pyrefhrum. 

"  Populine,  from  the  bark  and  leaves  of  Populus  tremula. 

"  Phillyrine,  from  the  bark  of  Phillyrea  media  and  latifolia. 

'*  Rhamnine,  from  Rhamnus  frangula. 

"  Scordine,  from  Teucrium  Scordium. 

**  Scutellarine,  from  Scutellaria  lateriflora. 

"  Serpentarine,  from  Aristolochia  serpentaria. 

"  Spartiine,  from  Spartium  monospermum. 

"  Spigeline,  from  the  root  and  leaves  of  Spigelia  anthelmia. 

"  Tanacetine,  from  Tanacetum  vulgare. 

"  Tremelline,  from  Tremella  mesentherica. 

"Zedoarine,  from  the  root  of  Curcuma  aromatica." 


OF  ETHERS.  529 

OF  ETHERS,  AND  THEIR  COMPOUNDS  AND  DERIVATIVES. 
Of  Ethyl  Ethers  (3090). 

5549.  Agreeably  to  the  classification  proposed  in  treat- 
ing of  ethyl  (3077),  common  ether,  the  oxide  of  that  com- 
pound radical,  as   the   first  in   the  class  of  simple  ethyl 
ethers,  is  primarily  to  be  the  object  of  attention. 

Of  the  Oxide  of  Ethyl,  common  Ether,  erroneously  called 
Sulphuric  Ether,  C4  H5O. 

5550.  It  has  been  mentioned,  that  this  compound  is  now 
called  ether,  on  account  of  a  sort  of  prescriptive  claim,  al- 
though the  name  by  which  it  is  designated  has  been  ap- 
propriated to  a  class  of  bodies  having,  in  common  with  it, 
some  important  characteristics  (3083). 

5551.  Of  the  Properties  of  the  Oxide  of  Ethyl. — The  ox- 
ide of  ethyl  is  a  colourless,  transparent,  volatile  liquid, 
having  only  seven-tenths  of  the  density  of  water,  or  seven- 
eighths  of  that  of  absolute  alcohol. 

5552.  It  is  so  inflammable,  that  a  jet  of  it  may  be  in- 
flamed throughout  its  whole  length,  when  extending  many 
feet.    It  has  a  fragrant  smell  and  an  aromatic  taste,  which, 
although  pungent  and  stimulating,  is  not  unpleasant.     Its 
density  to  that  of  water  at  60°,  is  as  725  to  1000.    It  boils 
between  97°  and  98°,  and  congeals  before  it  reaches  the 
temperature  of  — 47°.     With  alcohol  it  unites  in  all  pro- 
portions, but  may  be  recovered  therefrom  by  agitation 
with  twice  its  bulk  of  water,  which,  combining  with  the 
alcohol,  subsides  gradually,  allowing  the  liberated  ether  to 
form  a  superstratum  easily  separable. 

5553.  One  part  of  ether  dissolves  in  ten  of  water,  and 
one  part  of  this  liquid  in  thirty-six  of  ether.    Essential  oils 
are  soluble  in  ether  to  any  extent,  and  also  the  margarine 
and  olein  of  fixed  oils;  but  stearine  is  so  little  soluble  in 
ether,  that  it  is  employed  to  depurate  it.  of  the  two  other 
above  mentioned  constituents  of  fat.     Ether  is  likewise  a 
solvent  of  most  of  the  resins.     It  takes  gold,  in  the  metal- 
lic state,  from  a  solution  of  the  chloride  of  that  metal, 
forming  an  ethereal  solution,  which  has  been  employed  to 
gild  steel.     It  dissolves  several  of  the  haloid  compounds, 
especially  the  chloride  of  zinc  and  bichloride  of  mercury; 


530  ORGANIC  CHEMISTRY. 

also  several  organic  acids,  the  acetic,  gallic,  benzoic,  oleic, 
and  stearic,  for  instance.  The  solubility  of  various  or- 
ganic alkalies  in  ether  has  been  mentioned  in  treating  of 
their  extraction.  Of  sulphur,  it  takes  up  A  of  its  weight; 
of  phosphorus,  from  7V  to  aio-,  according  as  it  is  more  or 
less  free  from  water.  Bromine  and  iodine  are  copiously 
soluble  in  ether,  the  solutions  being,  however,  liable  to 
spontaneous  decomposition,  producing  bromohydric  and 
iodohydric  acid,  and  some  other  products  which  have  not 
been  studied. 

5554.  According  to  Liebig,  gaseous  chlorine  decomposes  ether  immedi- 
ately, each  bubble  inflaming  spontaneously  at  the  ordinary  temperature  of 
the  air,  giving  birth  to  chlorohydric  acid,  and  liberating  carbonic  acid.    An- 
hydrous sulphuric  acid,  in  the  cold,  generates  from  ether,  isethionic,  and 
ethionic  acid,  besides  heavy  oil  of  wine,  light  oil  of  wine  (5537),  and  sul- 
phovinic  acid.     At  a  high  temperature,  these  acids  are  resolved  into  heavy 
oil  of  wine,  water,  ether,  sulphurous  acid,  and  olefiant  gas. 

5555.  Nitric  acid,  aided  by  heat,  converts  ether  into  formic,  oxalic,  and 
carbonic  acid,  together  with  aldehyde. 

5556.  Of  chlorohydric  acid  gas,  ether  absorbs  a  large  quantity ;  and 
by  distilling  a  concentrated  solution,  chloride  of  ethyl  is  generated. 

5557.  Dry  alkaline  hydrates  have  no  reaction  with  pure  ether  at  ordi- 
nary temperatures,  but  when  moisture  and  oxygen  are  present  and  heat  is 
employed,  cause  it  to  become  brown  after  some  time,  and  to  form  alkaline 
acetates  or  formiates.    Potassium  and  sodium  are  alleged,  by  Liebig,  slowly 
to  deoxidize  ether,  and  finally  to  decompose  it  into  gaseous  and  oily  carbo- 
hydrogens,  forming  oxides  with  which  the  ether  combines  as  an  acid. 

5558.  In  presence  of  iron,  lead,  or  zinc,  with  access  of  oxygen,  this  ele- 
ment is  absorbed,  generating  acetates. 

5559.  Ammoniated  ether  may  be  obtained  by  subjecting  ether,  slaked 
lime,  and  chloride  of  ammonium,  to  the  distillatory  process. 

5560.  An  etherial  solution  of  the  bi-iodide  of  mercury  is  obtained  by 
the  solution  of  one  part  of  the  bi-iodide  in  twelve  parts  of  ether.     One  part 
of  the  bichloride  of  iron  dissolves  in  four  parts  of  ether.     On  agitating  an 
aqueous  solution  of  this  bichloride  with  ether,  this  liquid  takes  the  bichloride 
from  the  water,  forming  a  golden-yellow  liquor,  from  which  light  causes  a 
crystalline  protochloride  to  precipitate. 

5561.  In  consequence  of  the  solubility  of  narcotina,  and  insolubility  of 
morphia  in  ether,  it  is  employed  to  denarcotize  opium  in  preparing  it  for 
making  denarcotized  laudanum. 

5562.  The  tension  of  the  vapour  of  ether  being,  per  se,  adequate  to  sup- 
port a  pressure  about  half  as  great  as  that  of  the  atmosphere,  it  conse- 
quently doubles  the  volume  of  any  gas  to  which  it  may  be  added.     This 
may  be  made  evident  by  introducing  a  measured  quantity  of  any  gas  into  a 
volumescope,  and  adding,  subsequently,  a  portion  of  ether*  (818). 

*  Agreeably  to  the  experiments  of  Dalton,  the  vapour  of  any  liquid  in  contact  with 
the  air,  or  any  permanent  gas,  supports  a  proportion  of  the  atmospheric  pressure, 
which  bears  the  same  ratio  to  the  whole  pressure,  as  the  height  of  the  column  of  mer- 
cury, which  the  vapour  in  question  will  support,  per  se,  in  an  exhausted  receiver,  is 


OF  ETHERS.  531 

6563.  It  was  mentioned,  in  treating  of  olefiant  gas,  that  when  a  volume 
of  that  gas  was  mingled  with  four  volumes  of  hydrogen  and  two  of  oxy- 
gen, no  condensation  ensued  when  the  mixture  was  ignited.     The  elements 
of  the  gas  combining  with  those  of  water  in  the  act  of  uniting,  generated  a 
new  gas  containing  the  elements  of  both.     It  was  likewise  mentioned,  that 
half  a  volume  of  ether  had  about  as  much  efficacy  when  substituted  for  the 
olefiant  gas,  as  a  whole  volume  of  the  latter. 

6564.  This  is  interesting,  as  tending  to  show  that  in  the  same  space  ether 
vapour  contains  about  twice  as  much  carbon  and  hydrogen  as  olefiant  gas 
(1216). 

5565.  Of  the  Means  of  obtaining  Ether. — Respecting  the  means  by 
which  ether  is  elaborated,  a  general  explanation  has  already  been  given  in 
treating  of  ethyl  (3804).     The  old  recipe  for  its  manufacture,  was  to  distil 
two  measures  of  officinal  alcohol  of  about  0.840  with  one  of  sulphuric  acid, 
without  any  subsequent  addition  of  alcohol ;  but,  latterly,  the  proportions 
have  been  nearly  reversed  by  using,  at  the  outset,  nine  parts  of  acid,  by 
weight,  with  five  parts  of  alcohol,  the  proportion  of  this  liquid  being  sus- 
tained by  subsequent  additions,  compensating  the  diminution  resulting  from 
the  vaporization  of  the  products.     Liebig  recommends,  that  in  using  these 
proportions,  the  alcohol  be  added  to  the  acid  in  a  copper  or  cast  iron  vessel, 
the  liquids  being  mingled  by  stirring  them  with  an  iron  spatula;  but  agree- 
ably to  the  experience  of  a  manufacturer  in  this  vicinity,  who,  for  many 
years,  was  in  the  practice  of  distilling  a  large  quantity  of  the  etherifying 
materials  at  a  time,  it  is  preferable  to  introduce  the  alcohol  into  the  alembic 
first,  and  then  the  acid,  in  a  continued  stream.     This  stream,  by  its  supe- 
rior weight,  produces  a  descending  current,  carrying  along  with  it  the  alco- 
hol with  which  it  comes  into  contact,  and  forming  a  compound,  of  which 
the  boiling  point  is  about  280°.     The  descending  current  displacing  the 
liquid  previously  near  the  bottom  of  the  alembic,  causes  it  to  ascend  at  the 
sides,  and  thus  establishes  a  circulation,  by  which  a  complete  intermixture 
of  the  materials  is  effected.     The  heat  generated  meanwhile,  acting  upon 
some  of  the  alcohol  not  in  contact  with  the  acid,  is,  in  a  greater  or  less  de- 
gree, expended  in  vaporizing  a  portion  of  this  ingredient,  which,  condensing 
in  the  receiver,  should  be  restored  to  the  body  of  the  still  or  retort  employed. 
This  method  of  manipulation,  to  which  I  have  myself  long  resorted,  has  se- 
veral advantages  over  that  of  Liebig;  agreeably  to  which,  the  alcohol  being 
poured  over  the  acid,  and  in  contact  with  the  air,  must  sustain  some  loss  by 
evaporation.     The  mixture  being  made  in  one  vessel,  and  the  distillation  in 
another,  causes  unnecessary  trouble,  and  the  heat  generated  by  combina- 
tion is  lost,  which,  in  the  other  case,  requires  little  aid  from  the  fire  em- 
ployed to  cause  the  distillation  to  commence. 

5566.  The  most  advantageous  method  of  applying  heat  in  this  and  many 
other  cases,  is  that  already  described  of  a  furnace  having  coals  in  a  drawer 
which  can  be  withdrawn  in  an  instant,  partially  or  wholly,  so  as  to  render 
the  temperature  perfectly  controllable  (963).    Where  carburetted  hydrogen 

to  the  height  of  the  mercury  in  the  barometer  at  the  same  time.  Hence,  as  the  co- 
lumn which  the  vapour  of  ether  will  support,  per  se,  at  ordinary  temperatures,  is 
about  half  that  of  the  usual  height  of  the  barometric  column,  it  follows,  that  when 
liquid  ether  is  introduced  into  any  gas,  its  vapour  relieves  the  gas  of  half  the  pressure, 
and  at  the  same  time  deprives  it  of  half  the  space,  so  that  they  require  twice  as  much 
room  as  the  gas  required,  per  se ;  consequently  the  volume  of  the  mixture  becomes 
twice  as  great  as  that  of  the  gas  previously. 
68 


532  ORGANIC  CHEMISTRY. 

is  supplied  to  a  laboratory,  from  a  gas  light  establishment,  and  a  glass  re- 
tort is  to  be  used,  a  tube,  forming  a  circle  of  four  or  five  inches  diameter, 
and  perforated  at  intervals  of  about  half  an  inch,  so  as  to  allow  in  its  circum- 
ference from  twelve  to  twenty  gas  lights,  forms  an  efficient  mean  of  apply- 
ing a  competent  and  manageable  heat.  If  the  distillation  of  the  etherifying 
materials  be  carried  on  until  the  resulting  carbonaceous  mass  swells  up  so 
as  to  endanger  its  coming  over,  it  will  be  found  that  the  first  products  con- 
sist of  ether  with  undecomposed  alcohol,  then  ether  and  water,  and  after- 
wards ether  with  sulphurous  acid  and  heavy  oil  of  wine,  forming  a  yellow 
liquid.  But,  according  to  Liebig,  if  before  alcohol  ceases  to  come  over  in  a 
minute  proportion,  absolute  alcohol  be  gradually  added  by  a  tube,  with  a 
very  small  aperture  at  the  lower  end,  terminating  under  the  surface  of  the 
mixture  so  as  to  keep  it  at  the  same  level,  by  compensating  the  diminution 
resulting  from  the  distillation,  the  evolution  of  ether  and  water  continues 
without  the  extrication  of  sulphurous  acid  and  oil  of  wine.  If,  says  Liebig, 
"  the  operation  be  well  managed,  only  ether  and  water  will  be  evolved ;  and 
the  acid  may  serve  for  the  preparation  of  ether,  indefinitely,  without  per- 
ceptible diminution."  When  alcohol  of  the  officinal  density  is  used,  in  the 
way  thus  proposed,  the  acid  soon  becomes  too  much  diluted  to  perform  the 
office  of  an  etherifyer.  Liebig  admits  that  when  the  spirit  of  wine  employ, 
ed,  contains  90  per  cent,  of  anhydrous  alcohol,  only  31  parts  can  be 
etherified  by  90  of  sulphuric  acid,  and  when  the  proportion  of  water  to  the 
acid  exceeds  the  ratio  of  9  to  2,  ether  cannot  be  evolved.* 

5567.  As  respects  the  refrigeration  of  the  ether  vapour,  as  it  comes  over,  I 
have  been  accustomed  to  employ  an  inverted  open-necked  bell-glass,  through 
the  axis  of  which  a  glass  tube  passes,  being  made  to  form  an  air-tight  junc- 
ture with  the  neck,  by  means  of  a  gum  elastic  bag,  cut  off  near  the  bottom, 
so  as  to  embrace  the  neck  of  the  bell,  while  its  own  neck  embraces  the  tube, 
being  secured  to  both  by  ligatures.  The  beak  of  the  retort  is  drawn  out 
by  means  of  a  fire,  and  bent  at  right  angles  so  as  to  descend  into  the  upper 
orifice  of  the  refrigerating  tube.  The  bell  is  supplied  with  ice  and  water, 
this  liquid  being  drawn  off  by  a  syphon  as  the  ice  melts,  in  order  to  allow 
more  to  be  added.  The  refrigerating  tube  must  terminate  within  a  thin 
bottle,  surrounded  by  ice  and  water.  It  is  usually  recommended  to  separate 
the  ethereal  portion  of  the  product,  and  rectify  it  over  milk  of  lime,  or  a 

*  That  sulphovinic  acid  is  the  inevitable  consequence  of  mixing  and  heating  sul- 
phuric acid  with  alcohol  beyond  a  certain  point,  has  already  been  mentioned  in  treat- 
ing of  ethyl  (3036)  and  of  sulphovinic  acid  (5297).  This  combination  arises  probably 
from  the  affinity  of  hydrous  sulphuric  acid,  sulphate  of  water,  when  undiluted,  for 
etherine,  and  for  more  water,  so  that  while  one  portion  attracts  the  ether  of  the  alco- 
hol, the  other  attracts  the  water. 

Agreeably  to  the  representations  of  Liebig.  above  stated,  if,  during  the  etherifica- 
tion  of  alcohol  by  sulphuric  acid,  that  ingredient  be  supplied  in  the  proportion  neces- 
sary to  compensate  the  evolution  of  ether  and  water,  a  given  quantity  of  acid  may 
serve  to  etherify  alcohol  to  an  unlimited  extent.  The  fact  that,  under  such  circum- 
stances, only  the  alcohol  appeared  to  undergo  decomposition,  being  noticed  by  Mi- 
cherlith,  led  him  to  infer  that  the  part  performed  by  the  acid  was  merely  catalytic. 
But  this  inference  is  irreconcilable  with  the  well-established  fact  of  the  formation 
of  sulphovinic  acid  whenever  alcohol  and  sulphuric  acid  are  mingled  in  due  propor- 
tion and  heated  (5298).  Yet,  upon  this  view  of  the  phenomena  it  is  difficult  to  un- 
derstand how  the  mixture  can  at  the  same  time  evolve  ether  from  one  portion  of  the 
sulphovinic  acid  present,  and  yet  absorb  alcohol  to  form  another  portion  of  the  same 
acid  The  most  feasible  explanation  is,  that  the  contact  of  the  alcohol  with  the  acid, 
in  one  part  of  the  mixture,  causes  a  reduction  of  temperature  to  the  point  at  which 
the  acid  can  combine  with  oxide  of  ethyl,  while  in  other  parts  of  the  mixture,  the 
temperature  may  be  sufficiently  high  to  cause  other  atoms  of  the  same  base  to  be 
disunited  from  the  acid. 


OF  ETHERS.  533 

caustic  alkaline  solution,  with  the  heat  of  a  water  bath  of  about  120°.     I 
have  found  ammonia  the  most  speedy  agent  for  this  depurating  process. 

5568.  Agreeably  to  the  old  process,  oil  of  wine  was  generated  towards 
the  last.     Hence,  after  the  ether  was  distilled,  a  compound  of  alcohol  and 
oil  of  wine  remained,  and  could  be  brought  over  by  raising  the  water  bath 
to  a  boiling  heat.     Hoffman's  anodyne  liquor  was  thus  obtained. 

Of  heavy  Oil  of  Wine,  denominated  by  Liebig,  "the  double  Sulphate  of 
the  Oxide  of  Ethyl  and  Etherole"  the  true  Sulphuric  Ether,  C4  H5  O 
+  C4  H4  -f-  2SO3:  also  of  light  Oil  of  Wine. 

5569.  When  the  proportion  of  sulphuric  acid,  in  the  mixture  of  this  acid 
and  alcohol  employed  to  produce  ether,  becomes  sufficient  to  retain  the  ether 
until  the  temperature  rises  above  324°,  a  reaction  ensues  by  which  a  yellow, 
sulphurous,  ethereal  solution  of  oil  of  wine  comes  over  (3039)  (5299).    This 
consists  of  nearly  equal  parts  of  sulphurous  acid  and  ether,  the  oil  of  wine 
being  present  only  in  a  comparatively  minute  proportion.     This  liquid  be- 
ing subjected  to  distillation  at  a  heat  not  exceeding  120°,  the  greater  part 
of  the  ether  and  sulphurous  acid  may  be  brought  over.     The  residue  may 
then  be  exposed  in  vacuo  over  sulphuric  acid  and  slaked  lime.     By  these 
means  all  the  sulphurous  acid  ether,  and  water,  are  absorbed,  the  oil  of  wine 
being  isolated. 

5570.  Properties. — Thus  obtained,  oil  of  wine  has  an  unctuous  consist- 
ency, whence  its  name.     It  is  transparent,  nearly  colourless,  and  highly 
fragrant.     Its  taste  has  a  resemblance  to  that  of  peppermint. 

5571.  Of  the  Composition  of  Oil  of  Wine. — In  the  first  instance,  by 
Hennel,  and  afterwards  more  fully  by  Serallas,  that  kind  of  oil  of  wine 
which  is  designated  as  "  heavy,"  was  shown  to  be  a  chemical  compound  of 
sulphuric  acid,  carbon,  and  hydrogen.     Subsequently,  it  was  considered  as 
a  neutral  hyd rated  sulphate  of  etherine,  2C4  H4  +  HO  +  2SO3.     This,  of 
course,  contains  the  same  elements  as  if  it  were  considered  as  an  anhydrous 
neutral  sulphate  of  the  oxide  of  ethyl,  2C4  H5O  +  2SO3.     Lately,  it  has 
been  represented  by  Liebig,  as  a  double  sulphate  of  the  oxide  of  ethyl  and 
etherole;  this  last  mentioned  ingredient  being,  in  other  words,  etherine, 
OH4. 

5572.  Oil  of  wine,  thus  defined,  has  been  called  heavy  oil  of  wine,  be- 
cause it  sinks  in  water.     It  appears  that  it  may  be  more  or  less  deprived  of 
its  sulphuric  acid,  by  being  distilled  from  milk  of  lime,  or  by  being  digested 
with  caustic  alkaline  solutions,  and  then  forms  what  is  called  light  oil  of 
wine,  being  lighter  than  water.    From  the  heavy  oil,  when  free  from  water, 
I  was  unable  to  remove  the  acid  entirely  by  distillation  from  potassium. 

5573.  When  alcohol  is  etherified  by  chloride  of  zinc,  two  light  oils  are 
alleged  to  be  evolved,  one  having  the  formula  C8  H7,  the  other  C8  H9. 
Being  devoid  of  sulphuric  acid,  these  oils  are  of  course  quite  different  from 
the  heavy  oil,  of  which  the  formula  is  above  given.     The  allegations  re- 
specting the  composition  of  this  heavy  oil,  are  to  me  quite  unsatisfactory, 
and  lead  to  the  impression  that  we  are  still  ignorant  of  its  true  constitution. 
Nothing  can  be  more  anomalous,  and  inconsistent  with  the  laws  of  chemical 
combination,  with  which  experience  has  made  us  acquainted,  than  that  two  • 
atoms  of  an  acid,  being  comprised  within  a  compound,  and  one  of  them  in 
union  with  an  oxidized  radical  acting  as  a  base,  as  ether  does,  the  other  should 
refuse  to  unite  with  another  atom  of  that  base,  and  yet  combine  with  a  non- 
oxidized  radical,  etherole  or  etherine.     In  its  free  state,  this  last  mentioned 
compound  unites  neither  with  sulphuric  acid,  nor  any  other  acid,  and  yet 


534  ORGANIC  CHEMISTRY. 

it  is  represented  as  replacing  the  basic  water,  and  completely  neutralizing 
the  acid  properties  of  sulphoviriic  acid,  so  that  no  immediate  reaction  en- 
sues on  contact  with  the  most  powerful  bases.  It  is  unnecessary  to  repeat 
here  the  suggestions  respecting  the  bibasic  character  of  sulphovinic  acid, 
made  in  treating  of  its  inexplicable  properties  (5289). 

5574.  Of  Hoffman's  Anodyne  Liquor. — In  consequence  of  the  innova- 
tions made  in  the  manufacture  of  ether,  with  the  view  of  saving  the  acid, 
agreeably  to  the  explanations  above  given  (5566),  the  genuine  anodyne  li- 
quor of  Hoffman,  being  no  longer  a  collateral  product  of  that  manufacture, 
a  mixture  of  ether  and  alcohol  came  to  be  substituted  in  commerce  for  the 
true  medicine.     This  drew  the  attention  of  some  of  our  older  physicians, 
Dr.  Wistar,  and  my  late  colleague,  Dr.  Physick.     Dr.  Wistar  had  remark- 
ed that  the  modern  anodyne  liquor  did  not  produce  any  milkiness  in  water, 
when  added  to  it,  and  he  observed  that  the  presence  of  this  appeared  es- 
sential to  the  efficacy  of  the  medicament.     In  consequence  of  the  request 
of  Dr.  Physick,  having  given  some  attention  to  the  subject,  I  ascertained 
that  in  the  officinal  anodyne  there  was  generally  no  oil  of  wine,  and  hence 
nothing  to  be  separated  on  the  addition  of  water.     This  phenomenon  was 
found  only  to  ensue  in  the  anodyne  prepared  by  those  druggists  who  ad- 
hered to  the  old  method  of  manufacture.     As  both  by  Drs.  Physick  and 
Dewees,  much  value  was  attached  to  the  real  anodyne  "  as  highly  useful 
in  some  disturbed  states  of  the  system,  in  tranquillizing  and  disposing  to 
sleep,"  I  regret  that  no  efforts'  have  been  made,  by  those  who  are  in  the 
practice  of  medicine,  to  ascertain  whether  there  is  any  separate  efficacy  in 
the  oil  of  wine,  or  whether  it  operates  by  giving  greater  permanency  to  the 
impression  made  by  ether  by  lessening  its  volatility;  and  if  this  be  the  case, 
whether  other  essential  oils  cannot  be  used  in  lieu  of  oil  of  wine,  as  a  ve- 
hicle for  ether. 

5575.  A  Process  for  making  Hoffman's  Anodyne. — It  has  been  men- 
tioned, that  when  the  materials  employed  for  the  generation  of  ether  have 
a  certain  ratio,  and  the  temperature  reaches  a  certain  height,  a  yellow  liquid 
comes  over,  which  consists  of  heavy  oil  of  wine,  ether  and  sulphurous  acid. 
This  liquid  being  refrigerated  by  ice,  and  mingled,  gradually,  with  ammo- 
nia, also  refrigerated  in  a  bottle  surrounded  by  ice  water,  the  ethereal  solu- 
tion loses  about  half  its  bulk  and  weight.     The  residual  liquid,  which  floats 
upon  the  resulting  ammoniacal  solution,  being  separated  by  dilution  with 
twenty-four  parts  of  alcohol,  forms  the  anodyne  liquor  which  I  have  been 
accustomed  to  prepare. 

Of  Alcohol,  or  the  Hydrated  Oxide  of  Ethyl. 

5576.  In  treating  of  ethyl,  the  theoretical  composition 
of  alcohol  was,  I  trust,  sufficiently  explained  (3069).     I 
have  now  to  treat  of  the  means  of  obtaining  it,  and  of  its 
properties. 

5577.  Alcohol  can  only  be  obtained  through  the  me- 
dium of  the  process  called  the  vinous  fermentation,  being 
that  by  which  the  juice  of  the  grape,  of  the  apple,  or  pear, 
or  infusions  of  sugar,  or  farinaceous  substances,  are  ren- 
dered spirituous.     By  subjecting  fermented  liquors  thus 
originating,  to  distillation,  alcohol,  diluted  with  water,  and 


OF  ETHERS.  535 

flavoured  by  various  peculiar  empyreumatic  oils,  is  ob- 
tained, being  known  as  brandy,  rum,  or  whiskey,  accord- 
ingly as  it  may  be  derived  from  wine,  from  molasses,  or 
from  grain  or  cider. 

5578.  The  vinous  fermentation  may  be  induced  by  the 
addition  of  yeast  to  a  solution  of  sugar,  kept  between  60° 
and  70°.  During  this  process,  a  new  distribution  of  the 
elements  takes  place,  so  as  to  form  alcohol  and  carbonic 
acid.  One  atom  of  dry  grape  sugar,  C12  O12  H12,  is  con- 
verted into  two  atoms  of  alcohol,  2(C4  H5  O  +  HO)  and 
four  atoms  of  carbonic  acid,  4CO2. 

Two  atoms  of  alcohol,  C  8  H12  O 4 

With  four  atoms  of  carbonic  acid,        C 4        O 8 


Form  one  atom  of  sugar,  C12  H12  O12 

5579.  It  can  hardly  be  necessary  to  mention,  that  the 
intoxicating  power  of  the  various  liquids  known  generally 
in  commerce  as  spirits,  as  well  as  that  of  wine,  beer,  ci- 
der, and  other  fermented   liquprs,  is  due  to  the   alcohol 
which  they  contain.     These   spirits,  whether  known  as 
whiskey,  gin,  rum,  brandy,  or  arrack,  in  a  chemical  point 
of  view,  may  be  considered  as  mixtures  of  water  with  al- 
cohol.    Proof  spirits  is  a  term  applied  to  any  of  these 
mixtures,  when  consisting  of  their  principal  ingredients  in 
equal  proportion. 

5580.  When,  in  consequence  of  the  request  of  the  Bri- 
tish treasury  department,  a  committee  of  the  Royal  So- 
ciety undertook  to  make  a  table,  showing  the  relation  be- 
tween the  density  and  the  quantity  of  alcohol  in  a  series 
of  mixtures  of  this  liquid  and  water,  though  the  most  scru- 
pulous accuracy  was  displayed,  the  conclusion  was  adopt- 
ed, that  the  matter  existing  in  the  various  kinds  of  spirit, 
on  which  their  diversity  as  respects  flavour  and  value  is 
dependent,  was  too  small  to  require  to  be  taken  into  ac- 
count.    Nevertheless,  it  is  well  known  that  peculiar  vola- 
tile oils  accompany  the  whiskey  obtained  from  grain  and 
potatoes;  and  Ure  alleges,  that  spirit  obtained  from  da- 
maged grain,  has  been  found  to  contain  a  peculiar  volatile 
matter  augmenting  its  intoxicating  power,  so  as  to  produce 
in  some  persons  a  sort  of  frenzy.     This  matter,  at  the  end 
of  a  few  months,  was  spontaneously  decomposed,  so  as  to 
render  the  spirit  less  nauseous  and  unwholesome.     The 


536  ORGANIC  CHEMISTRY. 

impression  which  has  existed  in  this  country,  that  peach 
brandy  is  more  unwholesome  than  other  spirituous  liquids, 
may  depend  on  an  analogous  cause.  I  am  under  the  im- 
pression that  brandy  and  rum  contain  principles  which 
cause  their  peculiar  flavour,  and  that  the  difference  be- 
tween old  and  new  spirit,  is  due  to  the  modification  of 
those  essential  oils  on  which  the  peculiarity  of  quality  is 
in  such  cases  dependent. 

5581.  By  distilling  one-half  of  the  volume  from  proof 
spirit,  officinal  spirit  of  wine  is  procured,  and  by  careful 
rectification,  a  liquid  of  the  density  0.825  may  be  obtained, 
still  containing  eleven  per  cent,  of  water.    But  it  is  impos- 
sible for  the  vapour  of  any  liquid  to  be  formed  in  the  pre- 
sence of  another  liquid,  without  becoming  associated  with 
a  portion  of  its  vapour.     Besides,  the  inferior  density  of 
aqueous  vapour  creates  in  it  a  tendency  to  rise  within  the 
vapour  of  alcohol,  as  hydrogen  does  in  atmospheric  air. 
Hence  the  presence  of  two  or  three  per  cent,  of  water,  it 
is  alleged,  makes  the  boiling  point  of  alcohol  lower.     Con- 
sequently, a  more  aqueous  portion  distils  first  under  these 
circumstances.     But  on  the  other  hand,  when  the  propor- 
tion of  water  reaches  to  six  per  cent.,  the  result  is  invert- 
ed, so  that  the  product,  which  first  comes  over,  is  less 
aqueous  than  the  subsequent  product.     According  to  Gro- 
ning,  if  the  capital  of  the  still  be  kept  at  174°,  no  vapour 
which  contains  less  than  ninety  per  cent,  of  alcohol  can 
pass  over.     Of  course,  the  same  object  would  be  obtained, 
by  passing  the  beak  of  one  retort  into  the  tubulure  of  ano- 
ther quite  empty,  and  preserving  the  latter  at  a  proper 
temperature,  while  its  beak  is  made  to  communicate  with 
a  receiver  properly  refrigerated. 

5582.  Alcohol  may  likewise  be  concentrated  by  being 
subjected,  in  a  well  cleansed  bladder,  to  the  temperature 
of  122°.     The  bladder  is  made  more  efficient  by  being 
smeared  with  a  solution  of  gelatine,  four  times  inside  and 
twice  outside. 

5583.  But   to   procure  absolute  alcohol,  or,  in  other 
words,  that  which  is  devoid  of  water,  a  resort  must  be  had 
to  a  chemical  agent  having  a  great  affinity  for  water.    Re- 
cently ignited  carbonate  of  potash,  quick-lime,  or  fused 
chloride  of  calcium,  may  be  employed.    In  either  case,  the 
spirit  must  be  kept  in  contact  with  the  substance  employed 
for  some  time  before  distillation.     Chloride  of  calcium,  re- 


OF  ETHERS.  537 

cently  fused,  is  generally  preferred.  Of  the  spirit  of  wine 
of  not  more  than  0.833  in  density,  and  of  the  chloride  of 
calcium,  equal  weights  being  mixed  so  as  to  form  a  satu- 
rated solution  by  the  distillation  of  this  and  a  well  con- 
trived refrigerator,  half  the  volume  of  absolute  alcohol 
may  be  obtained.  In  this  state  it  has  a  specific  gravity, 
according  to  Ure,  of  0.791  at  68°. 

5584.  Alcohol  has  a  very  powerful  affinity  for  water,  so 
as  to  absorb  it  from  the  atmosphere,  and  from  organic 
substances  in  general.     It  is  by  neutralizing  water  that  it 
preserves  anatomical  preparations,  performing,  in  this  re- 
spect, a  part  analogous  to  that  of  brine.     As  the  freezing 
point  of  mixtures  of  this  liquid  with  water  is  extremely  low 
when  added  to  snow,  it  operates  as  deliquescent  salt,  and 
produces  cold  (419).     The  opposite  effect  results  from  its 
union  with  water,  as  it  forms  in  that  case  a  liquid,  of  which 
the  capacity  for  heat  is  less  than  the  sum  of  the  capacities 
of  its  ingredients.     Alcohol,  by  combustion,  yields  only 
water  and  carbonic  acid.     It  is  more  expansible  than  wa- 
ter, and  boils  at  176°.     Its  capacity  for  heat,  whether  in 
the  liquid  or  aeriform   state,  is  much  less  than  that  of 
water.     It  is  a  powerful  solvent,  and  highly  useful  agent 
in  pharmacy,  and  in  the  delicate  analysis  of  vegetable  and 
aninml  matter.     There  is  no  satisfactory  evidence  that  al- 
cohol has  ever  been  frozen.     The  most  intense  cold  pro- 
duced by  solid  carbonic  acid  and  ether,  by  Dr.  Mitchell, 
caused  it  to  become  syrupy  in  consistence,  but  did  not 
freeze  it.     The  addition  of  one-seventh  of  oil  of  turpentine 
will  render  the  flame  of  alcohol  so  luminous,  as  to  be  a 
competent  substitute  for  a  candle  flame.     When  alcohol 
is  passed  through  a  red-hot  porcelain  or  copper  tube,  it  is 
decomposed  into  water  and  carburetted  hydrogen. 

Of  EtherO'Sulphurous  Acid,  or  Sulphurous  Ether. 

5585.  Although  no  definite  compound  of  sulphurous  acid  with  the  oxide 
of  ethyl  has  been  made,  an  affinity  exists  between  this  acid  and  oxide,  re- 
sembling that  between  alcohol  and  water.     Sulphurous  acid  boils  at  — 12°, 
ether  at  98°,  the  difference  being  110°.     Of  course,  were  not  the  affinity 
between  these  fluids  more  energetic  than  that  between  alcohol  and  water,  of 
which  the  boiling  point  differs  only  by  36°,  they  would  not  remain  united  at 
ordinary  temperatures.     The  boiling  point  of  sulphurous  ether  is  lowered, 
in  proportion  as  the  ratio  of  the  acid  to  the  sulphuric  ether  is  increased. 
When  it  contains  oil  of  wine,  the  temperature  necessary  to  ebullition  of  the 
aggregate,  is  inversely  as  the  quantity  of  the  sulphurous  acid,  and  directly 
as  that  of  the  oil  of  wine,  to  the  quantity  of  the  other  ingredient.     Hence, 


538  ORGANIC  CHEMISTRY. 

although  I  have  obtained  sulphurous  ether,  which  boils  at  28°,  it  is  not  pos- 
sible, with  'the  heat  of  a  boiling  water  bath,  to  separate  the  last  portion  of 
this  ether  from  the  oil  of  wine,  since  a  part  of  the  latter  distils  with  it.  I 
kept  twenty-six  measures  of  the  compound  of  sulphurous  ether  and  oil  of 
wine  in  a  glass  measure,  over  water,  for  three  weeks,  without  the  slightest 
perceptible  diminution  of  the  quantity  of  the  former.  By  means  of  a  stop- 
ple secured  by  screws,  about  an  ounce  of  the  volatile  sulphurous  ether  was 
kept  in  contact,  with  water  for  more  than  six  weeks  without  apparent  altera- 
tion. Even  when  in  contact  with  ammonia,  the  transfer  of  the  acid  from 
the  ether  to  the  alkali  takes  place  slowly,  unless  agitation  be  employed. 

5586.  Of  Hyponitrite  of  the  Oxide  of  Ethyl,  Hyponitrite 
of  Ethyl,   Nitrite  of  Ethyl,   Nitric   Ether,   Nitrous   Ether, 
C4  H5O  +  NO3.     This  ethereal  compound  is  generated  by 
the  mixture  of  alcohol  with  nitric  acid,  provided  the  con- 
centration and  proportion  of  the  latter  and  the  tempera- 
ture, be  such  as  to  prevent  the  reaction  from  being  too 
violent;  in  which  case  the  products  are  liable,  according 
to  Liebig,  to  be  carbonic,  acetic,  and  formic  acid,  with 
acetic  and  formic  ether.    This  distinguished  chemist  omits 
to  mention  the  residual  elements  of  the  nitric  acid  em- 
ployed.    From  the  copious  display  of  red  fumes,  there 
seems  to  be  reason  to  infer  that  nitrous  or  hyponitrous 
acid  is  abundantly  evolved.     It  is  alleged  by  the  same 
author,  that  when  the  reaction  is  sufficiently  mitigated  by 
the  dilution  of  the  reagents,  and  moderation  of  the  tem- 
perature, only  aldehyde  and  hyponitrous  ether  are  gene- 
rated. 

5587.  Of  this  I  presume  the  following  rationale  may  be 
given: — From  an  atom  of  the  acid  employed,  two  atoms 
of  oxygen,  uniting  with  two  of  the  hydrogen  of  an  atom  of 
the  alcohol,  convert  it  into  aldehyde.     Meanwhile  three 
atoms  of  oxygen,  remaining  united  with  one  of  nitrogen,  in 
the  state  of  hyponitrous  acid,  combine  with  an  atom  of  the 
oxide  of  ethyl,  expelling  the  water  by  which  it  was  enabled 
to  exist  as  alcohol.    It  follows,  that  at  a  minimum,  one-half 
of  the  alcohol  must  be  destroyed. 

5588.  According  to  Liebig,  the  best  process  for  the  ge- 
neration of  this  ether,  in  purity,  is  to  impregnate  alcohol 
with  the  vapour  resulting  from  the  reaction  of  nitric  acid 
with  starch,  passing  the  aeriform  proceeds  through  a  well 
refrigerated  tube  to  a  receiver  in  a  similar  state.     I  have 
repeated  this  process  twice,  and  have  found  a  very  small 
quantity  of  pure  ether  to  be  produced,  with  comparatively 
large  consumption  of  the  materials. 


OF  ETHERS.  539 

5589.  I  conceive  that  the  best  process  is  that  of  which 
I  gave  an  account  about  four  years  ago,  and  which  is  as 
follows : — 

5590.  Fourteen  parts  of  the  hyponitrite  of  soda  with  just  enough  water 
for  its  solution,  seven  parts  of  alcohol,  eight  of  sulphuric  acid  diluted  with 
twelve  parts  of  water,  are  to  be  refrigerated,  and  introduced  into  a  bottle 
immersed  completely  in  water.     In  a  very  short  time,  hyponitrous  ether 
will  be  seen  swimming  on  the  mixture;  and  after  about  six  hours  the  pro- 
cess will  be  so  far  perfected,  as  to  make  it  expedient  to  decant  the  ether. 

5591.  In  lieu  of  including  the  materials  within  a  bottle,  as  above  de- 
scribed, the  salt,  previously  dissolved  in  water,  may  be  introduced  into  a 
tubulated  retort,  with  a  beak  recurved  and  adapted  to  a  refrigerating  appa- 
ratus and  receiver  surrounded  by  ice- water,  as  already  described.    Through 
the  tubulure  of  the  retort,  a  tapering  glass  tube,  terminating  in  an  orifice  of 
about  a  tenth  of  an  inch  in  diameter,  should  descend  nearly  to  the  bottom, 
being  secured  air-tight  to  the  tubulure  by  gum  elastic  or  other  lutings. 

5592.  The  alcohol,  acid,  and  water,  being  united  and  quite  cool,  may 
now  be  poured  in  through  the  tube;  the  ether  rapidly  generated  is  con- 
densed in  the  receiver  in  a  state  quite  free  from  aldehyde.     Water  contain- 
ing a  very  little  lime,  potash,  soda,  or  ammonia,  may  be  used  to  free  it  en- 
tirely from  acid,  and  quick-lime  to  free  it  from  water. 

5593.  Hyponitrous  ether,  thus  obtained,  differs  from  the  ether  ordinarily 
known  as  nitric  or  nitrous  ether,  in  having  a  more  bland  and  saccharine 
taste,  milder  odour,  and  greater  volatility.     It  boils  below  65°  F.,  and,  by 
its  spontaneous  evaporation  from  the  bulb  of  a  thermometer,  produces  a  cold 
of  153  below  zero,  F.     Touched  with  the  finger  or  tongue,  it  hisses  as  does 
water  with  a  red-hot  iron. 

5594.  If,  after  having  boiled  for  some  time,  it  be  allowed  to  stand  for 
a  while  at  a  temperature  below  its  boiling  point,  the  boiling  will  recommence 
at  a  lower  temperature  than  that  which  was  indicated  by  the  thermometer 
when  the  boiling  ceased. 

5595.  This  seems  to  arise  from  the  partial  re-solution  of  the  ether  into 
an  ethereal  gas,  which  appears  to  be  formed  by  the  materials  by  which  the 
liquid  ether  is  generated,  even  when  refrigerated  below  the  freezing  point. 
I  have  collected  this  aeriform  ether,  in  large  quantities,  in  bells  over  mer- 
cury.    When  subjected  to  great  pressure,  it  condenses,  more  or  less,  into  a 
yellow  liquid,  which  produces,  when  allowed  to  escape  into  the  mouth  or 
nostrils,  the  same  impression  as  the  liquid  ether.     I  have  conjectured  that 
this  ether  might  be  a  compound  of  the  liquid  ether  with  nitric  oxide  gas,  or 
that  it  may  be  isomeric  with  the  liquid  ether.     Notwithstanding  many  ef- 
forts to  obtain  a  liquid  ether  not  resolvable  partially  into  this  gas,  I  have 
never  succeeded.     Hence  the  boiling  point  is  extremely  variable,  as  I  have 
seen  bubbles  escaping  below  40°  from  the  liquid  ether,  when  recently  con- 
densed after  distillation. 

5596.  In  the  production  of  cold  by  mixture  with  solid  carbonic  acid,  Dr. 
J.  K.  Mitchell  found  this  ether  more  efficacious  than  that  commonly  known 
as  sulphuric  ether,  more  properly  called  hydric  ether. 

5597.  When  the  new  ether,  as  it  is  first  evolved,  is  distilled  from  pow- 
dered quick-lime,  this  earth  imbibes  an  essential  oil,  which,  with  the  aid  of 
water,  is  yielded  to  pure  hydric  ether.     Of  course,  it  is  easy  to  remove  this 
solvent  by  evaporation  or  distillation. 

69 


540  ORGANIC  CHEMISTRY. 

5598.  The  odour  of  this  oil  seems  to  be  an  ingredient  in  that  of  ordinary 
nitric  ether.     Possibly  the  hyponitrous  ether  may  resolve  itself  gradually 
into  this  oil  and  the  gaseous  ether,  so  that  its  boiling  point  may  be  probably 
varied  by  this  chemical  change.     I  suspect  that  the  essential  oil  in  question, 
is  one  of  the  impurities  which  causes  the  boiling  point  of  the  ether  generated 
by  nitric  acid  and  alcohol,  to  be  higher  than  the  boiling  point  of  that  ob- 
tained, as  in  my  process,  by  nascent  hyponitrous  acid. 

5599.  When  the  heat  is  raised,  after  the  volatile  ether  ceases  to  come 
over  from  the  materials  above  mentioned  as  producing  it,  ethereal  products 
are  distilled,  of  which  the  boiling  point  gradually  rises  as  the  process  pro- 
ceeds.    Meanwhile,  the  product  thus  obtained,  becomes   more  and   more 
acrid,  till  at  last  it  is  rendered  insupportable  to  the  tongue,  as  respects  the 
after  taste.     On  mingling  these  liquids  with  a  solution  of  green  sulphate  of 
iron,  the  ether  is  all  absorbed;  but  an  acrid  liquid,  which  causes  the  after 
taste,  is  not  absorbed,  and  may  be  separated  by  hydric  ether.     The  ether 
being  vaporized  by  heat,  the  acrid  liquid  remains.     The  smallest  drop  of 
this  liquid  is  productive  of  an  effect  upon  the  organs  of  taste  and  smell  like 
that  of  mustard  or  horse-radish. 

5600.  The  new  ether,  when  secured  in  a  glass  phial  by  means  of  a  well 
ground  stopper,  does  not  undergo  any  change  by  keeping  in  a  cool  situation 
for  several  months.     A  phial  was  suspended  about  fifteen  feet  below  the 
surface  of  the  ground,  in  a  cistern  of  water,  for  about  five  months;  another 
was  left  in  a  cool  cellar  for  a  longer  period,  without  any  apparent  change 
of  properties.    In  this  case  pressure  prevented  the  escape  of  the  ethereal  gas 
as  above  mentioned. 

5601.  All  the  ethereal  compounds,  formed  by  the  reaction  of  the  oxacids 
of  nitrogen  with  alcohol  appear  to  be  decomposable  by  green  sulphate  of 
iron.     Under  these  circumstances,  according  to  Berzelius,  a  malate  of  iron 
is  formed  from  common  nitric  ether. 

5602.  Concentrated  sulphuric  acid  absorbs  the  elements  derived  from  the 
alcohol,  and  liberates  nitric  oxide  gas,  which  is,  it  is  well  known,  rapidly 
absorbable  by  the  green  sulphate  above  mentioned.     Let  there  be  three  cy- 
lindrical glass  jars,  of  such  a  ratio  to  each  other  in  size,  as  to  allow  two  in- 
terstices of  about  half  an  inch  between  the  second  or  intermediate  jar,  and 
the  outer  and  innermost  jar;  likewise,  let  two  bell-glasses  be  provided,  of 
such  a  size  as  that  one  of  them  may  enter  the  inner  interstice,  while  the 
other  will  cover  and  descend  into  the  outer  interstice.     Let  a  wine  glass, 
containing  the  ether,  be  placed  in  the  innermost  jar,  and  let  the  outer  jar  be 
supplied  with  green  sulphate  of  iron,  the  other  two  with  concentrated  sul- 
phuric acid,  and  let  the  bells  be  put  in  their  respective  places. 

5603.  Under  these  circumstances,  the  ether  will  be  gradually  vaporized, 
and  the  alcoholic  elements,  with  some  oxygen,  will  be  absorbed  by  the  acid, 
while  nitric  oxide,  being  liberated,  will  pass  into  the  sulphate,  and  be,  con- 
sequently, absorbed. 

Of  the  Process  for  Sweet  Spirit  of  Nitre. 

5604.  This  name  is  applied  to  a  dilute  solution  of  im- 
pure hyponitrous  ether  in  alcohol,  which  has  acquired  its 
name  from  being  obtained  by  -subjecting  nitre  and  sulphu- 
ric acid  to  distillation  with  a  great  excess  of  alcohol.  The 
proportions,  agreeably  to  the  United  States  Dispensatory, 


OF  ETHERS.  541 

are  two  pounds  of  nitre,  one  and  a  half  pounds  of  acid,  nine 
half  pints  of  alcohol,  the  product  being  rectified  from  a 
pint  of  proof  spirit  and  an  ounce  of  carbonate  of  potassa. 
The  sweet  spirit  of  nitre  of  commerce  is  a  very  uncertain 
article  as  to  the  nature  and  proportion  of  its  ingredients, 
as  I  have  been  informed  by  eminent  druggists,  as  well  as 
physicians.  By  keeping,  it  becomes  partially  acidified, 
whereas  I  have  kept  pure  hyponitrous  ether  in  a  cool  cel- 
lar for  nearly  a  year  without  deterioration.  I  am  of  opi- 
nion, that  it  would  be  advantageous  if  the  prescriptions  of 
our  physicians  were  made  with  reference  to  ingredients  of 
a  high  degree  of  purity.  The  physician  should  know  how 
much  real  ether  is  contained  in  the  diluted  article  which 
he  directs  his  patient  to  use.  Hence  the  pure  hyponitrite 
or  oxide  of  ethyl  should  be  prescribed,  adding  as  much  al- 
cohol or  water  as  may  be  deemed  necessary.  Agreeably 
to  the  present  practice,  it  is  in  the  power  of  manufacturing 
chemists  to  impoverish  ethereal  preparations  with  little 
danger  of  detection. 

5605.  Pursuant  to  the  London  Pharmacoposia,  three 
ounces  of  nitric  acid,  by  distillation  with  a  quart  of  alco- 
hol, are  allowed  to  produce  twenty-four  fluid  ounces  of 
sweet  spirit  of  nitre.    According  to  Thenard,  the  quantity 
of  ether,  when  the  materials  are  in  the  ratio  of  equality, 
amounts  to  two-thirds  the  weight  of  the  acid.     Hence  it  is 
probable,  that  the  quantity  of  ether  in  twenty-four  fluid 
ounces  of  sweet  spirit  of  nitre,  obtained  as  above  men- 
tioned, is  not  more  than  two  ounces.     I  infer  that  sweet 
spirit  of  nitre,  of  a  more  uniform  strength,  would  be  ob- 
tained by  the  addition  of  alcohol  to  pure  nitric  ether,  to  an 
extent  no  more  than  adequate  to  render  it  soluble  in  water, 
and  then  adding  water  to  the  alcoholic  solution,  until  the 
ether  should  form  (only  a  twelfth  of  the  aggregate.     In  a 
preparation  thus  made,  the  properties  of  the  ether  would 
not  be  unnecessarily  associated  with  those  of  alcohol,  as 
in  the  usual  officinal  preparation. 

Of  the  Perchlorate  of  the  Oxide  of  Ethyl,  or  Perchloric  Ether. 

5606.  This  ether  was  discovered,  in  my  laboratory,  by  Mr.  Martin  Boy6 
and  Mr.  Clark  Hare. 

5607.  It  was  obtained  by  subjecting  about  ninety  grains  of  crystallized 
sulphovinate  of  baryta,  with  an  equivalent  proportion  of  perchlorate  of  ba- 
ryta, to  the  distillatory  process,  receiving  the  product  in  from  one  to  two 
drachms  of  absolute  alcohol.    By  complex  affinity,  the  sulphuric  acid  of  the 


542  ORGANIC  CHEMISTRY. 

sulphovinate  dispossesses  the  perchloric  acid  of  the  baryta,  while,  at  the 
same  time,  the  last  mentioned  acid  combines  with  the  oxide  of  ethyl. 

5608.  The  perchlorate  of  ethyl  is  a  transparent,  colourless  liquid,  pos- 
sessing a  peculiar,  though  agreeable  smell,  and  a  very  sweet  taste,  which, 
on  subsiding,  leaves  a  biting  impression  on  the  tongue,  resembling  that  of 
the  oil  of  cinnamon,  but  more  acrid  and  enduring.    It  is  heavier  than  water, 
through  which  it  rapidly  sinks.     It  explodes  by  ignition,  friction,  or  percus- 
sion, and  sometimes  without  any  assignable  cause.     Its  explosive  properties 
may  be  safely  shown,  by  pouring  a  small  portion  of  the  alcoholic  solution 
into  a  small  porcelain  capsule,  and  adding  an  equal  volume  of  water.     The 
ether  will  collect  in  a  drop  at  the  bottom,  and  may  be  subsequently  sepa- 
rated by  pouring  off  the  greater  part  of  the  water,  and  throwing  the  rest  on 
a  moistened  filler,  supported  by  a  wire.     After  the 'water  has  drained  off, 
the  drop  of  ether  remaining  at  the  bottom  of  the  filter  may  be  exploded 
either  by  approaching  it  to  an  ignited  body,  or  by  the  blow  of  a  hammer. 
The  violence  and  readiness  with  which  this  ether  explodes  is  not  surpassed 
by  that  of  any  other  known  compound.     By  the  smallest  drop,  an  open 
porcelain  plate  may  be  reduced  into  fragments,  and  by  a  larger  quantity,  to 
powder.     In  consequence  of  the  force  with  which  it  projects  the  minute 
fragments  of  any  containing  vessel  in  which  it  explodes,  it  is  necessary  that 
the  operator  should  wear  gloves,  and  a  close  mask,  furnished  with  thick 
glass-plates  at  the  apertures  for  the  eyes,  and  perform  his  manipulations 
with  the  intervention  of  a  moveable  wooden  screen.* 

5609.  In  common  with  other  ethers,  the  perchlorate  of  ethyl  is  insoluble 
in  water,  but  soluble  in  alcohol;  and  its  solution  in  the  latter,  when  suffi- 
ciently dilute,  burns  entirely  away  without  explosion.     It  may  be  kept  for 
a  length  of  time  unchanged,  even  when  in  contact  with  water;  but  the  addi- 
tion of  this  fluid,  when  employed  to  precipitate  it  from  its  alcoholic  solution, 
causes  it  partially  to  be  decomposed.     Potassa,  dissolved  in  alcohol,  and 
added  to  the  alcoholic  solution,  produces  immediately,  an  abundant  precipi- 
tate of  the  perchlorate  of  that  base,  and,  when  added  in  sufficient  quantity, 
decomposes  the  ether  entirely. 

5610.  The  perchlorate  of  ethyl  has  been  subjected  to  the  heat  of  boiling 
water  without  explosion  or  ebullition. 

5611.  It  may  be  observed  that  this  is  the  first  ether  formed  by  the  com- 
bination of  an  inorganic  acid  containing  more  than  three  atoms  of  oxygen 
with  the  oxide  of  ethule,  and  that  the  chlorine  and  oxygen  in  the  whole 
compound  are  just  sufficient  to  form  chlorohydric  acid,  water  and  carbonic 
.oxide  with  the  hydrogen  and  carbon.     It  is  also  the  only  ether  which  is  ex- 
plosive per  se. 

Of  Acetic  Ether,  or  Acetated  Oxide  of  Ethyl,  C4  H3  O3  -f  O  H5  O. 

5612.  In  common  with  other  oxacid  ethers,  this  ether  may  be  obtained 
agreeably  to  the  principles  already  set  forth  (5303),  by  distilling  alcohol 
and  sulphuric  acid,  or  in  other  words,  sulphovinic  acid,  with  any  acetate,  or 
any  sulphovinate  with  concentrated  acetic  acid. 

5613.  Acetic  ether  is  colourless,  burns  readily  with  a  pale  yellow  flame, 
has  a  refreshing  odour,  with  a  density  of  0.890  at  60°.     It  boils  at  165°, 
does  not  redden  litmus,  is  soluble  in  seven  parts  of  water,  and  in  every  pro- 

*  For  the  particulars  of  the  process  I  refer  to  the  American  Philosophical  Transac- 
tions, Vol.  8,  New  Series-,    also  to  Silliman's  Journal,  Vol.  42,  for  1842,  page  63. 


OF  ETHERS.  543 

portion  in  alcohol  or  ether.  In  general  it  is  a  solvent  of  all  the  substances 
which  dissolve  in  this  last  mentioned  liquid.  By  alkalies  it  is  readily 
decomposed,  likewise  by  sulphuric  acid  by  which  it  is  resolved  into  ether 
and  acetic  acid. 

Of  Oxalic  Ether,  or  Oxalated  Oxide  of  Ethyl,  C4  H5O  +  O4  H3  O3. 

5614.  This  ethereal  compound,  discovered  by  Thenard,  may  be  obtained 
by  the  following  process  : — Four  parts  of  binoxalate  of  potash  are  mixed  in 
a  retort,  with  five  parts  of  oil  of  vitriol,  and  four  parts  of  alcohol,  of  840°, 
and  briskly  distilled.     As  soon  as  the  product  becomes  turbid  on  the  addi- 
tion  of  water,  the  receiver  is  changed.     The  subsequent  product  being 
quickly  mixed  with  four  times  its  bulk  of  water,  the  ether  sinks  to  the  bot- 
tom.    It  should  be  separated  and  washed  with  successive  portions  of  water, 
till  it  becomes  neutral  to  test  paper.     The  ether  thus  washed  is  transferred 
to  a  small  dry  retort,  filled  up  to  nine-tenths  of  its  capacity,  and  rectified. 
As  soon  as  the  product  becomes  clear,  and  the  boiling  goes  on,  regularly, 
the  receiver  is  changed.     What  now  passes  over  is  pure  anhydrous  oxalate 
of  the  oxide  of  ethyl  (oxalic  ether) — (Ettling).     It  is  a  colourless,  transpa- 
parent,  oily  fluid,  of  sp.  g.  1.0929  at  46°,  boiling  at  370°,  miscible  with 
alcohol  and  ether,  and  having  a  peculiar  aromatic  smell.     In  a  state  of  pu- 
rity it  may  be  kept  many  days  under  water,  in  which  it  is  very  sparingly 
soluble  without  decomposition;  but  when  it  contains  but  a  minute  proportion 
of  free  acid  or  alcohol,  it  is  speedily  decomposed  into  oxalic  acid,  which  is 
deposited  in  large  four-sided  prisms,  and  alcohol.    The  same  reaction  ensues 
with  an  excess  of  fixed  alkali. 

Of  Carbonic  Ether,  or  Carbonated  Oxide  of  Ethyl,  C4  H5O  -f  CO3. 

5615.  Discovered  by  Ettling  by  the  following  means : — Fragments  of 
potassium  being  added  to  oxalic  ether,  duly  warmed,  as  long  as  any  gas  is 
evolved  and  any  excess  of  the  metal  removed,  the  resulting  mass  was  sub- 
jected to  distillation.     Carbonic  ether  was  generated,  and  being  conveyed 
into  the  receiver,  formed  a  superstratum  upon  the  other  products  of  the  pro- 
cess.    Being  separated,  and  freed  from  water  by  the  chloride  of  calcium, 
it  was  redistilled  from  potassium  till,  on  contact  with  caustic  potash,  no  ox- 
alate could  be  formed. 

5616.  Carbonic  ether  is  colourless,  ethereal,  and  very  liquid,  having  an 
ardent  taste,  and  an  aromatic  odour,  resembling  the  ether  from  which  it 
originates.     It  is  lighter  than  water,  has  the  specific  gravity  0.975  at  66°, 
boils  at  260°,  and  burns  feebly  with  a  blue  flame.     It  may  be  mingled  in 
all  proportions  with  alcohol  and  ether,  but  is  insoluble  in  water.     When 
mixed  with  an  alcoholic  solution  either  of  the  hydrate  of  potash  or  soda,  it 
is  quickly  resolved  into  alcohol  and  an  alkaline  carbonate,  which  separates 
in  water  as  an  oily  concentrated  solution,  or  forms  as  a  crystalline  powder, 
if  no  water  be  present.    The  formation  of  carbonic  ether,  which  is  attended 
by  the  production  of  several  substances  not  yet  examined,  is  still  unex- 
plained. 

Formiated  Oxide  of  Ethyl,  or  Formic  Ether,  C4  H5O  +  C3H  O3. 

5617.  To  prepare  formic  ether,  seven  parts  dry  formiate  of  soda  are  dis- 
tilled with  ten  parts  of  sulphuric  acid,  and  six  of  alcohol,  of  about  830°. 

5618.  Formic  ether  is  generated,  and  comes  over  for  the  most  part  with- 
out the  application  of  heat.     It  is  depurated  of  acid  by  milk  of  lime,  and 


544  ORGANIC  CHEMISTRY. 

from  water  by  chloride  of  calcium,  which  should  be  added  so  long  as  it  be- 
comes moist  (5281). 

5619.  Formic  ether  is  a  limpid  liquid,  of  a  penetrating,  aromatic  odour, 
being  of  the  density  of  0.912.     It  boils  at  128.     Its  taste  is  cooling  and 
spicy.     It  requires   for  its  solution  ten  parts  of  water,  but  dissolves  in  all 
proportions  in  alcohol  and  ether,  in  pyroxylic  spirit  and  several  fixed  -and 
volatile  oils.     It  is  acidified  by  exposure  to  air. 

OfBenzoated  Oxide  of  Ethyl,  or  Benzole  Ether,  C14  H5  O  -f  C4  H5  O. 

5620.  This  ether,  discovered  by  Sheele,  and  analyzed  by  Woehler  and 
Liebig,  is  generated  by  distilling  a  mixture  of  four  parts  of  alcohol,  of  830°, 
two  parts  of  crystallized  benzoic  acid,  and  one  of  concentrated,  liquid,  chlo- 
rohydric  acid.     As  soon  as  the  product  renders  water  turbid,  the  receiver 
should  be  changed,  as  what  passes  over  subsequently   is  benzoic  ether. 
The  ether,  thus  obtained,  must  be  added  to  water  to  separate  it,  and  be  af- 
terwards boiled,  with  water  and  litharge,  to  remove  free  benzoic  acid,  and, 
lastly,  digested  with  chloride  of  calcium. 

5621.  Benzoic  ether  is  colourless,  neutral,  and  very  liquid,  having  an 
ethereal  but  suffocating  odour,  and  provoking  tears.     Its  specific  gravity, 
at  50°,  is  1.0539.     It'bpO*  at  410°,  is  soluble  in  alcohol  and  ether,  but  in- 
soluble in  water.     It  is  decomposed  by  chlorine,  according  to  Malagutti, 
producing,  among  other  products,  chloride  of  benzule. 

Of  the  Tartrate  and  Citrate  of  the  Oxide  of  Ethyl,  and  other  "Salts" 
of  Ethyl,  so  called,  of  minor  importance. 

5622.  There  are  few  oxacids  which  may  not  be  united  with  the  oxide  of 
ethyl  and  other  oxidized  compound  radicals,  so  as  to  form  combinations  in 
composition  analogous  to  the  complex  ethers.     Those  formed  with  citric 
and  tartaric  acid,  are  hardly  ethereal  in  their  properties.     The  citrate  re- 
quires a  heat  of  540°  for  ebullition,  and  is  partially  decomposed  during  dis- 
tillation.    The  tartrate,  not  being  capable  of  neutralization,  is  more  a  con- 
gener of  sulphovinic  acid,  viewed  as  a  bibasic  acid  (5290),  than  of  the  com- 
plex ethers  (3079). 

5623.  I  shall  forbear  to  treat  of  various  compounds,  analogous  in  com- 
position to  those  above  described,  whether  having  the  oxide  of  ethyl,  or  any 
other  oxidized  compound  radical,  as  a  base,  for  reasons  like  those  already 
given  in  relation  to  the  acids  (5397). 

Of  (Enanthated  Oxide  of  Ethyl,  or  (Enanthic  Ether,  C4H5O+C14H1303. 

5624.  This  liquid  is  called  ethereal  oil  of  wines,  by  Graham,  which  tends 
to  confound  it  with  the  oil  of  wine,  Liebig's  sulphate  of  ethyl  and  etherole. 
It  is  alleged  to  be  the  cause  of  the  characteristic  odour  by  which  wines  are 
generically  distinguished  from  dilute  alcohol.     It  forms  a  portion  of  the  re- 
sidue of  the  distillation  of  brandy  from  wines  in  the  large  way.    It  is  said  to 
constitute  about  one  part  in  40,000  of  wine.     The  bouquet  by  which  some 
wines  are  distinguished,  ought  to  be  ascribed  to  this  ethereal  compound. 

5625.  (Enanthic  ether  is  a  colourless  liquid,  having  an  intense  odour  of 
wine,  almost  intoxicating  when  plentifully  inspired,  and  a  strong  disagree- 
able taste.     It  is  soluble  in  ether  and  in  alcohol,  whether  concentrated  or 
dilute ;  but  not  in  water.     Its  density  is  362 ;  its  volatility  feeble.     It  re- 
quires a  temperature  between  434  and  446  for  ebullition.     This  ether  is 
instantly  decomposed  by  fixed  caustic  alkalies ;  but  not  by  ammonia,  or 


OF  ETHERS.  545 

alkaline  carbonates.  When  distilled  with  caustic  potash,  it  is  resolved  into 
alcohol,  which  comes  over,  and  a  very  soluble  oenanthate  of  potash. — Gra- 
ham's Elements. 

Of  Simple  Ethers,  formed  by  the  Substitution  of  another  Basacigen  Body 
for  Oxygen  in  the  Oxide  of  Ethyl;  or  for  the  Hydrogen  in  the  Water 
united  with  that  Oxide. 

5626.  Chloride  of  ethyl,  C4  H5  Cl,  also  called  chlorohydric  ether,  for- 
merly, muriatic  ether. — It  must  be  evident,  from  the  comparison  of  the  for- 
mula above  given,  with  that  of  ether,  C4  H5  O,  that  this  chloride  differs 
from  that  oxide,  only  in  the  substitution  of  an  atom  of  chlorine  for  an  atom 
of  oxygen. 

5627.  Chloride  of  ethyl  is  generated  by  the  distillatory  reaction  of  chlo- 
rohydric  acid,  or  various  chlorides,  either  with  the  oxide  of  ethyl,  with  al- 
cohol, or  any  other  of  the  compounds  of  that  oxide,  such  as  acetic,  citric, 
oxalic,  tartaric  ether,  &c.     Agreeably  to  one  process,  alcohol  is  to  be  first 
saturated  with  chlorohydric  acid  gas;  according  to  another,  it  should  be 
distilled  with  an  equivalent  proportion  of  a  strong  aqueous  solution  of  that 
acid,  by  means  of  a  glass  retort,  communicating  by  a  tube  with  some  water, 
at  a  temperature  of  about  90°  F.,  in  a  bottle  with  three  orifices.     Through 
one  orifice,  the  tube  proceeding  from  the  retort  enters,  and  is  luted  air-tight; 
into  another  orifice,  a  tube  of  safety  is  inserted;  from  the  third  orifice  pro- 
ceeds another  tube,  arranged  so  as  to  communicate,  through  a  refrigerating 
apparatus,  with  the  interior  of  a  phial  surrounded  by  a  freezing  mixture. 
The  water  in  the  intermediate  vessel  detains  any  alcohol  or  acid  evolved 
with  the  ether,  which,  in  consequence  of  its  greater  volatility,  reaches  the 
phial.     The  product  is  freed  from  water  and  alcohol  by  digestion,  for  twen- 
ty-four hours,  on  chloride  of  calcium,  cooled  by  ice-water. 

5628.  Chloride  of  ethyl  is  a  colourless,  ethereal  liquid,  with  an  aromatic, 
penetrating,  and  somewhat  alliaceous  odour.     Its  density  is  .874  at  41°. 
It  boils  at  52°;  does  not  redden  litmus;  dissolves  in  twenty-four  parts  of 
water,  producing  a  solution  which  has  a  fresh,  aromatic  taste.     With  solu- 
tions of  silver  it  gives  no  precipitate.     It  burns  with  a  bright  flame,  green 
at  the  border,  evolving  fumes  of  chlorohydric  acid.     In  passing  through  an 
incandescent  tube,  it  is  resolved  into  equal  volumes  of  that  acid,  and  defiant 
gas.     The  exposure  of  this  chloride  to  gaseous  chlorine,  aided  by  the  solar 
rays,  has  given  rise  to  a  series  of  compounds.     It  is  decomposed  after  some 
time,  by  the  alkaline  hydrates,  into  a  chloride  of  the  ingredient  metals, 
and  alcohol. 

5629.  Bromide  of  ethyl,  C*  H5  Br,  was  discovered  by  Serullas,  by  dis- 
tilling a  mixture  of  one  part  of  bromine,  four  of  alcohol,  and  one-eighth 
of  phosphorus.     It  is  a  colourless  liquid,  denser  than  water,  and  very  vo- 
latile. 

5630.  Iodide  of  ethyl,  C4  H5  I,  may  be  obtained  by  distilling  alcohol, 
saturated  with  hydriodic  acid  gas.     It  is  a  colourless  liquid,  of  the  density 
of  1.9206.     It  boils  at  161°. 

5631.  Sulphide  of  ethyl,  C4  H5  S,  is  formed  by  transmitting  the  vapour 
of  chlorohydric  ether,  through  an  alcoholic  solution  of  the  proto-sulphuret 
of  potassium;  the  chlorine  being  precipitated  with  the  potassium,  the  sul- 
phur unites  with  the  ethyl  and  is  dissolved,  or  distils  over,  if  kept  suffi- 
ciently warm.     It  is  a  colourless  liquid  ;  the  boiling  point,  135°;  density, 
0.825  at  68°. 


546  ORGANIC  CHEMISTRY. 

5632.  Sulphydrate  of  the  Sulphide  of  Ethyl,  or  Mercaptan,  C4  H5  S 
+  HS. — It  might  be  advantageously  called  sulphalcohol,  since  sulphur 
performs  in  it  the  part  allotted  to  oxygen  in  alcohol  proper,  sulphydric  acid 
occupying  the  place  of  water,  as  may  be  perceived  by  the  name  and  for- 
mula. 

56.33.  The  best  way  to  prepare  this  compound,  discovered  by  Zeise,  is 
to  distil  a  solution  of  the  sulphovinate  of  lime,  of  the  density  of  1.28,  with 
a  solution  of  sulphydrate  of  the  sulphide  of  potassium,  generated  by  satura- 
ting a  solution  of  potash,  also  of  the  density  of  1.28,  with  sulphydric  acid 
gas. 

5634.  The  product  may  be  condensed  by  means  of  a  refrigerating  ap* 
paratus,  like  that  mentioned  as  having  been  used  for  ether  (5567).     It 
may  be  purified  from  an  excess  of  sulphydric  acid,  alcohol  and  water,  by  a 
second  distillation  from  a  small  quantity  of  red  oxide  of  mercury,  and  sub- 
sequent digestion  with  chloride  of  calcium.     Mercaptan  boils  at*  100°  near- 
ly, being  a  colourless,  ethereal  liquid,  with  a  most  penetrating  and  insup- 
portable alliaceous  odour.      Its  density  is  said  to  be  0.835  at  70°,    an$ 
0.842  at  59°.     It  is  soluble  in  alcohol  and  ether,  but  it  is  very  slightly  so- 
luble in  water.     The  sulphydric  acid  of  mercaptan  reacts  powerfully  with 
metallic  oxides,  generating  water,  and  a  sulphide  of  the  metal.     This  sul- 
phide remains  in  combination  with  the  sulphide  of  ethyl,  thus  forming  a 
class  of  sulphur  salts.     The  oxide  of  mercury  is  instantly  converted,  by 
mercaptan,  into  a  compound  of  this  class,  the  mercaptide  of  mercury,  C4  H5 
S  -f  Hg  S,  which  is  a  white,  crystalline  mass,  soft  to  the  touch,  without 
odour,  insoluble  in  water,  and  fusible,  like  wax,  at  185°.     This  mercaptide 
when  distilled  leaves  cinnabar,  and  affords  a  volatile  liquid,  which  has  not 
been  examined.     The  oxide  of  gold  is  also  strongly  acted  on  by  mercaptan ; 
but  other  metallic  oxides  are  less  affected  in  proportion  as  they  are  more 
electro-positive.     Thus,  the  hydrates  of  potash  and  soda  have  no  sensible 
reaction  with  mercaptan.     When  gently  heated,  with  nitric  acid,  mercaptan 
is  converted  into  a  new  acid,  which  contains  sulphide  of  ethyl,  and  the  ele- 
ments of  sulphuric  acid,  C4  H5  S3  O3  (Loewig,  Kopp). 

5635.  Bisulphide   of   ethyl,   C4  H5  S3.— A   transparent,  oily  liquid, 
which  boils  at  123.8°,  is  obtained   by  distilling  a  mixture  of  sulphovi- 
nate of  potash  and  the  persulphide  of  potassium.     It  is  decomposed  by 
caustic  potash,  or  by  nitric  acid  (Zeise,  Pyrame,  Morin). 

5636.  Selenide  of  ethyl  is  obtained,  according  to  Loewig,  in  the  same 
way  as  the  sulphide,  substituting  in  the  process,  selenide  of  potassium  for 
the  sulphide  of  potassium. 

5637.  Telluride  of  ethyl,  C4  H5,  a  very  volatile  liquid,  of  a  deep  orange 
colour  (Wheeler),  may  be  obtained  also  by  a  similar  process,  using  the  tel- 
luride  of  potassium. 

5638.  Cyanide  of  ethyl,  improperly  called  cyanhydric  ether,  =  C4  H5N, 
is  a  colourless  liquid,  with  an  insupportable  odour  of  garlic,  was  obtained 
by  Pelouze,  by  exposing  a  dry  mixture  of  sulphate  of  ethyl  and  potash  to 
a  gentle  heat,  gradually  increased.     It  has  also  been  formed  by  distilling  a 
mixture  of  sulphocyanide  of  potassium,  alcohol,  and  sulphuric  acid.    It  is  a 
thick,  oily  liquid,  of  the  density  of  0.7,  boiling  at  179.6°. 


OF  ETHERS.  547 

Of  the  Dehydrogenation  and  Oxidation  of  Ethyl,  as  con- 
tained in  Ether  or  Alcohol,  and  of  the  Oxidation  of  the 
residual  Products. 

5639.  The  precipitation  of  carbon  which  gives  a  fuligi- 
nous character  to  the  flame  of  essential  oils  and  resins, 
has  been  ascribed  to  an  inadequate  supply  of  oxygen,  and 
the  superior  affinity  of  hydrogen  for  oxygen,  comparative- 
ly with  carbon,  at  moderate  temperatures.   In  consequence 
of  this  preference  thus  given,  when  some  of  the  compounds 
of  ethyl  are  subjected  to  oxidating  agents,  in  processes 
below  the  temperature  of  ignition,  more  or  less  hydrogen 
is  removed   according  to  the  intensity  of  the  reaction. 
Thus,  from  alcohol  C4  H5O  +  HO,  two  atoms  of  hydrogen 
being  taken,  aldehyde  is  engendered,  C4H3O  + HO.    These 
elements,  by  the  absorption  of  one  atom  of  oxygen,  form 
an  acid  which  has  been  called  aldehydic  acidj  or  acetous 
acid,  C4  H3  O3  +  HO.     Another  atom  of  oxygen  converts 
this  acid  into  acetic  acid,  C4  H3  +  O3  +  HO.     Aldehydic 
acid  has  also  been  designated  as  acetows  acid,  having  the 
same  radical,  and  less  oxygen  than  acetzc  acid  (3094). 

5640.  Acetyl,  of  which  the  formula  is  C4  H3O,  has  been 
already  described  as  a  compound  radical,  indebted  for  its 
existence  to  the  removal  of  two  of  the  five  atoms  of  hydro- 
gen belonging  to  ethyl  (3093).     Liebig  attributes  this  re- 
sult to  the  oxidation  of  the  ethyl ;  but  it  is,  as  I  conceive, 
a  case  of  dehydrogenation  of  ethyl,  resulting  from  the  oxi- 
dation of  two-fifths  of  its  hydrogen.    The  relation  between 
this  radical  and  its  progeny  may  be  seen  in  the  following 
table. 

Acetyl,                                  -             -  C4H3 
Aldehydic,  or  hydrate  of  the  oxide  of  ace- 

tyl,      -  C4H3O  +  HO. 

Acetous,  or  aldehydic  acid,               -  C4  H3O2  +  HO. 

Acetic  acid,  C4H3O3-f  HO. 

No  oxide  of  acetyl  has  been  ascertained  to  exist  uncom- 
bined  with  water  and  corresponding  to  common  ether. 

Of  the  Hydrated  Oxide  of  Acetyl,  called  Aldehyde. 

5641.  By  inspection  of  the  respective  formulae,  it  will 
be  perceived,  that  this  compound  differs  from  alcohol  only 

70 


548  ORGANIC  CHEMISTRY. 

in  the  loss  of  two  atoms  of  hydrogen.  Hence  its  name 
from  the  first  syllable  of  each  of  the  words  alcohol  and  de- 
Aydrogenatum.  Aldehyde  is  one  of  the  products  of  the 
decomposition  of  alcohol,  or  ether,  by  passage  through  a 
tube  at  a  low  red  heat:  during  etherification  by  nitric  acid 
(5586):  by  platina  wire  in  the  lamp  without  flame,  and  in 
other  cases.  Liebig's  process  for  the  preparation  of  alde- 
hyde is  as  follows : — Six  parts  of  oil  of  vitriol  with  four  of 
water ;  four  parts  of  spirits  of  wine  and  six  of  black  oxide 
of  manganese,  are  to  be  distilled  with  a  very  gentle  heat, 
and  the  product  collected  in  a  receiver  surrounded  with 
ice-water.  This  process  is  completed  as  soon  as  the  ma- 
terials in  the  retort  cease  to  froth  up.  Kane  observes  that 
a  purer  product  may  be  obtained  by  distilling  two  parts  of 
spirits  of  wine  with  three  of  bichromate  of  potash,  three  of 
oil  of  vitriol,  and  six  of  water;  the  two  last  being  previous- 
ly mixed  and  allowed  to  cool.  To  obtain  aldehyde  abso- 
lutely pure,  it  must  be  combined  with  ammonia;  the  result- 
ing crystallized  ammoniacal  compound  must  afterwards  be 
decomposed  by  dilute  sulphuric  acid,  distilled,  by  means  of 
a  water-bath  at  120°,  with  great  care,  and  finally  rectified 
over  fused  chloride  of  calcium. 

5642.  Aldehyde  is  a  colourless,  inflammable  liquid,  of  a 
peculiar  ethereal  and  suffocating  odour.     It  boils  at  72% 
has  the  density  0.790  at  64.40,  and  is  soluble  in  water, 
alcohol  and  ether.     By  absorbing  atmospheric  oxygen,  it 
is  converted  spontaneously  into  acetic  acid.     It  dissolves 
phosphorus,  sulphur  and  iodine.    Aldehyde  is  capable  of 
combining  directly  with  ammonia  and  potash,  thus  evincing 
an  approach  to  the  acid  character. 

5643.  Ammoniated  Aldehyde,  or  the  Hypoacetite  of  Ammo- 
nia, C4  H3O,  NH3  -f  HO.     In  this  compound  aldehyde  ap- 
pears to  act  as  an  acid  in  entering  into  union  with  the  oxide 
of  ammonium  (1106),  so  that  it  might  be  consistently  de- 
signated as  hypoacetous  acid.   Ammoniated  aldehyde  crys- 
tallizes in  acute,  colourless,  transparent,  brilliant,  friable 
rhomboids,  of  a  considerable  magnitude,  and  which  have 
an  odour  of  spirit  of  turpentine.     These  crystals  fuse  be- 
tween 150°  and  172°,  and  distil  without  decomposition,  at 
212°.    They  burn  with  a  yellow  flame.    In  the  air,  or  even 
in  closed  phials,  they  turn  brown,  acquiring  the  smell  of  a 
burnt  feather.     Under  pure  ether  they  may  be  preserved, 
but  not  for  a  long  time.     These  crystals  are  soluble  in 


OF  ETHERS.  549 

water  in  all  proportions,  and  more  readily  in  hot  than  in 
cold  alcohol.  In  ether  they  are  but  little  soluble. 

5644.  Acetal,  a  compound  of  aldehyde  with  ether,  C4  H5O  -f  C4  FPO 

-f-  HO  =  C8  H9  O5,  was  discovered  by  Dobereiner,  and  described  as  oxy- 
genated ether.  It  is  formed  by  the  reaction  of  platinum  black  with  the  va- 
pour of  alcohol,  with  the  presence  of  oxygen.  Acetal  is  a  colourless  liquid, 
having  a  peculiar  odour,  suggesting  that  of  Hungary  wines.  It  boils  at 
203° ;  its  density  is  0.823  at  68°.  It  is  soluble  in  six  or  seven  parts  of 
water,  and  mixes  with  alcohol  in  all  proportions. 

5645.  The  crude  formula  of  acetal  being  C8  H9  O3,  two  atoms  of  it 
•will  be  found  to  contain  the  ingredients  of  three  atoms  of  ether,  and  one 
of  acetic  acid. 

5646.  Resin  of  aldehyde  is  a  product  of  the  decomposition  of  aldehyde 
by  alkalies,  with  the  assistance  of  air. 

5647.  Elaldehyde. — When  pure  anhydrous  aldehyde  is  kept  for  some 
time  at  32°,  while  gradually  losing  its  power  to  mix  with  water,  it  is  trans- 
formed into  a  coherent  mass  of  long,  transparent,  needle-shaped  crystals,  re- 
sembling spiculaB  of  ice.     This  is  elaldehyde,  which  is  similar  in  composi- 
tion to  aldehyde,  but  of  three  times  the  atomic  weight,  judging  from  the 
density  of  its  vapour.     Elaldehyde  fuses  at  35.6°,  and  boils  at  201.2°. 

5648.  Metaldehyde  is  another  product  of  the  condensation  of  the  ele- 
ments of  aldehyde,  which  appears  in  aldehyde  left  for  some  time  in  a  well- 
stopped  phial,  in  the  form  of  white  and  transparent  needles,  or  colourless 
prisms,  which  gradually  attain  a  certain  magnitude.     It  sublimes  at  248°, 
without  fusing,  and  condenses  in  the  air  in  snowy  and  very  light  flocks. 
It  is  insoluble  in  water,  but  dissolves  easily  in  alcohol. 

Of  some  interesting  Results  of  the  substitution  of  Chlorine,  Bromine,  Sul- 
phur, and  other  Basacigen  Bodies,  for  the  Hydrogen  or  the  Oxygen 
in  the  Compounds  of  Ethyl  and  Acetyl. 

5649.  Of  the  Chlorohydrate  of  the  Chloride  of  Acetyl,  Chlorine  Ether, 
Bichlorine  Ether,  C4  H3  Cl  +  01  H.— Under  the  head   "olefant  gas" 
(1274),  it  was  mentioned  (1292)  that  olefiant  gas  received  its  name  from 
its  capacity  of  forming  a  liquid  of  an  oily  consistency,  having  an  agreeable 
smell  and  taste.     On  account  of  its  resemblance  to  ethereal  compounds,  as 
respects  fragrance,  solubility  and  taste,  and  the  presence  in  it  of  two  atoms 
of  chlorine,  it  has  been  called  bichlorine  ether.     Considering  olefiant  gas 
as  a  hydruret  of  acetyl,  C4  H3  +  H,  the  liquid  in  question  is,  by  Liebig, 
treated  of  under  the  appellation  at  the  head  of  this  article,  which  indicates  it 
to  consist  of  chlorohydric  acid,  CH,  and  chloride  of  acetyl,  C4  H3  Cl. 

5650.  This  liquid  is  usually  made  by  the  confluence  of  equal  volumes 
of  moist  chlorine  and  the  gas  above  mentioned,  within  a  large  receiver, 
over  water.     Liebig  recommends  the  reaction  of  the  same  olefiant  gas 
with  the  perchloride  of  antimony,  so  long  as  there  is  any  absorption. 
The  resulting  mass  is  to  be  subjected  to  distillation,  till  the  product  ceases 
to  yield  any  ethereal  liquid  on  the  addition  of  water.     The  combination 
thus  elaborated,  requires  to  be  depurated  by  redistillation  with  water,  and 
subsequent  agitation  with  sulphuric  acid  to  depurate  it  of  moisture.     This 
ordeal  is  to  be  repeated  until  it  ceases  to  be  affected  by  sulphydric  acid,  or 
to  emit  chlorohydric  acid  during  distillation.     Finally,  being  successively 
washed  with  water,  and  kept  in  contact  with  chloride  of  calcium,  it  becomes 
quite  pure. 


550  ORGANIC  CHEMISTRY. 

5651.  Thus  obtained,  the  chlorohydrate  of  the  chloride  of  acetyl  is  co- 
lourless, very  liquid,  and,  as  respects  smell  and  taste,  sweet  and  agreeable. 
It  boils  at  179°.     It  maybe  distilled,  without  decomposition,  from  the  alka- 
line  hydrates.     It  communicates   its  smell  to  water,  although  insoluble 
therein.     In  alcohol  and  ether  it  dissolves  in  all  proportions.     By  an  alco- 
holic solution  of  potash,  it  is  decomposed  into  chloride  of  potash  and  chlo- 
ride of  acetyl.     It  was  by  the  exposure  of  this  chlorohydrate  to  reaction 
with  chlorine,  in  the  sunshine,  that  Faraday  (1*242)  obtained  the  sesqui- 
chloride  of  carbon. 

5652.  Chloride  of  Acelyl. — This  is  a  gaseous  product,  of  which  men- 
tion is  above  made  as  resulting  from  the  reaction  of  its  chlorohydrate  with 
potash,  in  alcohol.     It  has  an  alliaceous  odour,  and  may  be  liquefied  at  the 
temperature  of — 6°. 

5653.  Bromohydrate  of  Bromide  of  Acetyl,  Bromide  of  Acetyl,  lodo- 
hydrate  of  Iodide  of  Acetyl. — Substances  are  described  by  Liebig,  to  which 
these  names  are  given,  which  indicate  their  analogy  with  the  two  com- 
pounds of  chlorine  last  described. 

5654.  Chloroplatinate  of  Chloride  of  Acetyl. — By  this  name  a  com- 
pound has  been  designated,  in  which  chloroplatinic  acid  takes  the  place  of 
chlorohydric  acid  in  the  chlorohydrate  of  the  chloride  of  acetyl. 

5655.  Oxychloride  of  Acetyl,  C4  H3  Cl2  O.— This  name  has  been  given 
to  a  colourless  oily  liquid,  which  results  from  the  saturation  of  anhydrous 
ether  with  chlorine,  desiccated  by  being  passed  through  concentrated  sul- 
phuric acid.    The  formula  of  ether  being  C4  H5  O,  two  out  of  the  five  atoms 
of  hydrogen  are  converted  into  chlotohydric  acid,  while  two  atoms  of  chlo- 
rine supply  their  place.     Thus  the  oxychloride  of  acetyl  is  generated  by  a 
process  analogous  to  that  by  which  acetic  acid  is  generated,  oxygen  per- 
forming, in  one  case,  the  same  part  as  chlorine  in  the  other. 

5656.  It  must  be  evident  that  we  have,  in  the  formula  of  this  compound  as 
above  given,  the  ingredients  of  acetyl  combined  both  with  oxygen  and  chlo- 
rine.    It  is  therefore  designated  as  an  oxychloride,  although  usually  this 
name  has  been  applied  to  the  union  of  an  oxide  and  a  chloride,  each  seve- 
rally combined  with  distinct  atoms  of  the  same  radical. 

5657.  Oxysulphide  of  Acetyl,  C4  H3  S3  O. — In  this  compound,  sulphur 
occupies  the  place  which  chlorine  fills  in  the  oxychloride  of  acetyl,  and  of 
course  that  which  oxygen  fills  in  anhydrous  acetous  acid.     The  substitution 
of  sulphur  is  effected  by  the  reaction  of  the  oxychloride  of  acetyl  with  sul- 
phydric  acid;  during  which,  the  two  atoms  of  chlorine  uniting  with  the  two 
of  hydrogen,  two  atoms  of  sulphur  supply  the  place  of  the  chlorine  thus  re- 
moved.    During  this  last  mentioned  reaction,  another  compound  is  formed, 
in  which  only  one  atom  of  the  chlorine  in  the  oxychloride  is  replaced  by 
sulphur.     The  formula,  of  course,  is  C4  H3  Cl  SO.     The  ethyl  in  acetic 
ether  may,  by  reaction  with  chlorine,  have  its  hydrogen  so  far  replaced  by 
chlorine  as  to  be  converted  into  an  oxychloride,  while  its  union  with  the 
acetic  acid  remains  unbroken.     Benzoic  ether  may  not  only  have  its  base 
similarly  changed,  but  the  oxygen,  forming  its  acid  with  benzule,  may  be  re- 
placed by  chlorine;  so  that  for  Bz  O  -f-  C4  H5O,  a  compound  results,  re- 
presented by  Bz  Cl  +  C4  H3  Cla  O. 

5658.  Chloroxalic  Ether,  C4  Cl5  O  -f  C3  O3.— This  ether  is  created  by 
the  substitution  of  chlorine  for  the  whole  of  the  hydrogen  in  oxalic  ether,  of 
which  the  formula  is  C4  H5  O  -f-  C3  O3.    It  will  be  seen,  on  comparing  these 
formulae,  that  they  differ  only  in  this;  five  atoms  of  chlorine  in  one  are  sub- 
stituted for  a  like  number  of  hydrogen  in  the  other.     It  was  obtained  by 


OF  ETHERS.  551 

subjecting  oxalic  ether  in  a  retort,  surrounded  by  boiling  water  and  exposed 
to  the  solar  light,  to  a  current  of  chlorine. 

5659.  Chloral,*  C4  H3O  -f-  HO,  is  the  name  given  to  a  compound  dis- 
covered by  Liebig,  in  which  all  the  hydrogen  of  aldehyde  is  replaced  by 
chlorine.     It  might,  with  propriety,  1  think,  be  called  hydrated  oxide  of 
chloracetyl,  chloracetyl  being  understood  to  apply  to  the  compound  C4  Cl3, 
which  takes   the  place  of  acetyl  as  the  organic  radical.     Chloral  is  the 
ultimate  product  of  the  dehydrogenation   of  anhydrous  alcohol,   by  dry 
chlorine,  and  the  substitution  of  three  atoms  of  chlorine  for  five  of  hy- 
drogen. 

5660.  By  subjecting,  for  twelve  or  fifteen  hours,  anhydrous  alcohol  to 
chlorine,  dried  by  passage  through  sulphuric  acid,  a  copious  evolution  of 
chlorohydric  acid  ensues,  and  a  dense  oily  liquid  is  generated,  which  con- 
geals on  cooling,  being  an  impure  hydrate  of  chloral.     It  is  requisite  to 
check  the  reaction  in  the  first  instance  by  immersion  in  water,  afterward  to 
assist  by  heat  the  expulsion  of  the  chlorohydric  acid.     The  hydrate  is  pu- 
rified first  by  heating  it  in  a  well-stopped  flask,  with  nearly  three  times  its 
bulk  of  sulphuric  acid,  when  the  chloral,  depurated  of  water,  forms  a  super- 
natant stratum.     This  being  separated,  and  boiled  to  expel  free  chlorohy- 
dric acid,  or  alcohol,  to  remove  any  residual  moisture,  the  chloral  should 
be  distilled  from  an  equal  volume  of  sulphuric  acid.     Finally,  it  must  be 
rectified  from  lime,  which,  after  being  slaked,  was  rendered  anhydrous  by 
exposure  to  a  bright  red  heat. 

5661.  Chloral,  thus  obtained,  is  a  dense,  oily,  colourless  liquid,  greasy 
to  the  touch,  having  a  penetrating,  disagreeable  odour,  which  provokes 
tears.     Its  taste  is  at  first  greasy,  then  caustic.     It  produces  on  paper  an 
evanescent  stain.     Its  density,  at  64.4°  is  1502;  its  boiling  point  is  201°, 
nearly.     It  may  be  distilled  without  alteration.     Its  vapour  is  nearly  five 
times  as  dense  as  that  of  air,  its  equivalent  being  four  volumes.     Chloral  is 
miscible  either  with  alcohol  or  ether.     Aided  by  heat  it  dissolves  sulphur, 
phosphorus,  or  iodine,  apparently  without  alteration. 

OF  METHYL  ETHERS. 
Of  the  Oxide  of  Methyl,  or  Methylic  Ether,  C2  H3  O. 

5662.  In  treating  of  the  hypothetical  compound  radical, 
methyl,  it  was  stated,  that  it  was  considered  as  performing, 
in  the  compound  above  mentioned,  a  part  analogous  to 
that  which  ethyl  is  inferred  to  perform  in  alcohol. 

5663.  The  oxide  of  methyl  is  prepared  by  distilling  one 
part  of  wood  spirit,  with  four  parts  of  sulphuric  acid,  the 
resulting  gas  being  transmitted,  successively,  through  a 
bottle  containing  milk  of  lime,  and  several  bottles  duly 
charged  with  pure  water.     In  this  liquid  the  gas  dissolves, 
and  being  evolved  by  a  boiling  heat,  may  be  collected  over 
mercury.     Oxide  of  methyl  is  an  inflammable,  colourless 

*  The  account  of  chloral,  given  under  the  head  of  inorganic  compounds  of  carbon, 
being  very  brief,  I  have  not  hesitated  to  treat  of  it  again,  as  an  organic  product, 
without  reference  to  that  imperfect  notice. 


552  ORGANIC  CHEMISTRY. 

gas,  of  an  agreeable  ethereal  odour.  For  liquefaction  it 
requires  a  temperature  below  3.2°.  Thirty-seven  volumes 
of  this  gas  dissolve  in  one  of  water.  Alcohol,  hydrated  ox- 
ide of  methyl,  and  concentrated  sulphuric  acid,  take  it  up 
to  a  greater  extent.  From  the  latter  it  separates  on  dilu- 
tion with  water.  The  density  of  the  gas  is,  by  experiment, 
1605;  by  calculation,  1570;  its  combining  measure  being 
two  volumes. 

5664.  By  combining  with  the  vapour  of  anhydrous  sul- 
phuric acid,  in  a  glass  balloon,  carefully  cooled,  the  oxide 
of  methyl  forms  a  neutral  sulphate.     (Regnault.) 

Of  Hydrated  Oxide  of  Methyl,  called  Pyroxylic,  or  Wood 
Spirit,  Methylic  Alcohol,  C2  H3  O  +  HO. 

5665.  In  the  process  of  purifying  acetic  acid  from  wood 
(5199),  the  crude  acid  is  saturated  by  lime,  and  concentrated 
by  distillation,  of  which  the  first  product  contains  the  crude 
wood  spirit,  which  may  be  partially  purified  by  repeated 
distillation  from  quick-lime;  and  is  found  in  this  state  in 
commerce.     It  is  still  a  heterogeneous  mixture,  containing, 
besides  the  hydrated  oxide  of  methyl,  which    forms  the 
larger  part  of  it,  acetone,  and  several  other  volatile  and 
inflammable  liquids.     To  purify  the  spirit  in  question,  it  is 
treated  with  an  excess  of  chloride  of  calcium,  in  a  retort, 
and  distilled  by  a  water-bath  heat,  which  expels  the  more 
volatile  liquids,  and  leaves  the  wood  spirit  in  union  with 
the  chloride  of  calcium.     A  volume  of  water,  equal  to  the 
volume  of  wood  spirit  employed,  is  then  added  to  the  re- 
tort,  and   the  distillation   continued.     The  spirit   comes 
over  imbued  with  a  small  quantity  of  water,  from  which  it 
may  be  completely  separated   by  subsequent  distillation 
from  quick-lime  (5711,  &c.). 

5666.  Wood  spirit  is  a  volatile,  colourless  liquid,  simul- 
taneously recalling  the  taste  and  odour  of  acetic  ether  and 
alcohol.     It  is  very  inflammable,  and  burns  with  a  pale 
flame.     It  mixes  with  pure  water  without  becoming  turbid, 
and  likewise  with  alcohol  and  ether.     Its  density  is  0.798 
at  68°;  its  boiling  point,  140°.     The  density  of  its  vapour  is, 
by  experiment,  1120;  by  calculation,  1100;  its  combining 
measure  or  equivalent  comprises  four  volumes. 

5667.  With  the  aid  of  heat,  hydrated  oxide  of  methyl 
dissolves  small  portions  of  sulphur  and  phosphorus,  and 
may  also  serve  as  a  solvent  for  the  resins  employed  in 


OF  ETHERS.  553 

making  varnishes.  It  mixes  with  volatile  oils.  Wood 
spirit  is,  like  alcohol,  acted  upon  by  chlorine,  peroxide  of 
manganese  or  sulphuric  acid,  and  by  oxidizing  agents  in 
general,  and  yields  analogous  products.  It  is  also  decom- 
posed by  potassium,  with  disengagement  of  pure  hydrogen. 

5668.  Anhydrous  barytes,  although  not  soluble  in  alco- 
hol, dissolves  in  pure  wood  spirit,  with  much  heat,  and 
forms  a  compound,  C2  H3  O  HO  +  Ba  O,  which  crystal- 
lizes in  needles  of  a  silky  lustre.     Lime  is  likewise  soluble 
in  wood  spirit. 

5669.  Chloride  of  calcium  dissolves  eagerly  in  this  sol- 
vent, so  as  to  cause  much  heat.     From  a  concentrated 
solution,  it  crystallizes  in  large,  deliquescent,   hexagonal 
tables,  which  contain  two  atoms  of  hydrated  oxide  of  me- 
thyl, united  with  one  atom  of  chloride  of  calcium. 

5670.  Neutral  Sulphated  Oxide  of  Methyl,  C2  H3  SO3.— This  member 
of  the  methyl  series,  which  has  no  analogous  compound  in  that  of  ethyl,  is 
generated  either  when  oxide  of  methyl  and  anhydrous  sulphuric  acid  are 
brought  into  contact,  or  when  one  part  of  the  hydrated  oxide  is  distilled 
with  eight  or  ten  parts  of  sulphuric  acid ;  the  product  being  purified  by 
washing  with  water,  and  distillation  from  chloride  of  calcium  and  quick- 
lime, successively.     Sulphated  oxide  of  methyl  is  a  colourless  liquid,  of  an 
alliaceous  odour,  of  density  1.324  at  71°. 6.     It  boils  at  370°. 4,  and  may 
be  distilled  without  change.     The  density  of  its  vapour  is  4363.4 ;  it  con- 
sists of  equal  volumes  of  anhydrous  sulphuric  acid  and  oxide  of  methyl, 
condensed  into  one  volume ;  its  combining  measure  being  four  volumes,  the 
same  as  that  of  oxide  of  methyl.     It  is  very  slowly  decomposed   by  water 
when  cold,  but  rapidly  when  hot;  the  acid  sulphated  oxide  of  methyl  and 
water  being  formed,  while  oxide  of  methyl  is  liberated.     By  double  decom- 
position this  compound  may  be  employed  in  preparing  all  the  other  com- 
pounds of  methyl. 

5671.  Acid  'Sulphated  Oxide  of  Methyl,  Bisulphated  Oxide  of  Methyl, 
Sulphomethylic  Acid,  C2  H3O  +  S3  O6  HO.     This  congener  of  sulphovi- 
nic  acid,  discovered  by  MM.  Dumas  and  Peligot,  and  by  Dr.  Kane,  about 
the  same  time,  is  formed  by  mixing  concentrated  sulphuric  acid  with  hy- 
drate of  oxide  of  methyl;  or  by  dissolving  the  neutral  sulphate  in  boiling 
water.     Obtained  by  the  latter  method,  and  concentrated  by  evaporation,  it 
is  a  colourless,  syrupy,  and  very  acid  liquid ;  which,  in  dry  air,  becomes  a 
mass  of  white  crystalline  needles.     It  combines  with  bases  forming  double 
salts,  in  which  the  basic  water  of  the  acid  is  replaced  by  a  metallic  oxide. 
These  double  salts  are  soluble  in  water. 

5672.  Nitrated  Oxide  of  Methyl,  Me  O  NO5.— To  prepare  this  com- 
pound, one  part  of  nitrate  of  potash,  and  a  mixture  of  two  parts  of  concen- 
trated sulphuric  acid  with  one  part  of  wood  spirit,  are  introduced  into  a  re- 
tort.    The  mass  rises  in  temperature,  and  a  liquid  distils  without  additional 
heat.     For  its  condensation,  a  refrigerated  tube  should  be  employed,  termi- 
nating in  a  refrigerated  flask.     The  heavier  of  the  two  liquids  found  in  the 
flask  is  nitrated  oxide  of  methyl,  contaminated  by  a  portion  of  a  very  vola- 
tile compound,  supposed  to  be  formiated  oxide  of  methyl,  which  imparts  the 


554  ORGANIC  CHEMISTRY. 

odour  of  cyanhydric  acid.  The  product  is  rectified  from  chloride  of  cal- 
cium and  from  litharge.  The  last  portions  which  distil  over  are  perfectly 
pure.  Nitrated  oxide  of  methyl  is  a  colourless  liquid,  of  a  weak,  ethereal 
odour,  which  burns  readily  with  a  yellow  flame;  its  density  is  1.822  at 
71°.6,  and  boiling  point  150°. 8.  Heated  above  248°,  its  vapour  is  decom- 
posed explosively,  producing  carbonic  acid,  water,  and  deutoxide  of  nitro- 
gen. This  ether  is  soluble  in  water,  and  miscible  in  all  proportions  with 
alcohol,  ether,  and  wood  spirit. 

Of  the  Hyponitrite  of  the  Oxide  of  Methyl,  or  Methylic  Hyponitrous 
Ether.  "Nitrite  d1  Oxide  de  Methyl"  of  Liebig,  and  others. 

5673.  In  his  late  Treatise  on  Organic  Chemistry,  Liebig  makes  the  fol- 
lowing statement: — "The  reaction  which  nitric  acid  exercises  with  the  hy- 
drated  oxide  of  methyl,  is  not  like  that  which  it  exercises  with  alcohol, 
since,  while  this  liquid  is  decomposed  with  great  difficulty,  giving  birth  to 
certain  oxidized  products  and  hyponitrite  of  the  oxide  of  ethyl,  the  hydrated 
oxide  of  methyl  is  not  altered  by  nitric  acid,  unless  at  a  boiling  heat. 
When  a  great  excess  of  this  acid  is  employed,  formic  and  oxalic  acid  are 
generated,  but  no  hyponitrite  ("nitrite")  nor  nitrate  of  the  oxide  of  methyl. 
It  would  seem,  therefore,  that  the  hyponitrite  of  the  oxide  of  methyl  does 
not  exist."     Traite,  552. 

5674.  Last  winter,  however,  Dec.  1841,  I  found  that  by  subjecting  pure 
wood  spirit  to  the  process  already  described  for  producing  the  hyponitrite  of 
ethyl,  a  congenerous  ethereal  product  was  obtained  (5583).    Hyponitrite  of 
methyl  has  a  great  resemblance  to  its  congener  above  named,  in  colour, 
smell,  and  taste;  though  there  is  still  a  diversity  sufficient  to  enable  a  care- 
ful observer  to  distinguish  one  from  the  other. 

5675.  \^hen  the  process  in  which  hyponitrous  ether  is  generated,  by  in- 
troducing the  refrigerated  materials  into  a  bottle  surrounded  by  ice  and 
water,  was  resorted  to,  substituting  wood  spirit  for  alcohol,  it  was  found  that 
the  ether  did  not  separate  from  the  spirit  as  completely  as  in  the  process  in 
which  alcohol  was  the  material.     This  I  ascribe  to  the  affinity  between 
water  and  wood  spirit  being  inferior  to  that  between  this  last  mentioned  li- 
quid and  alcohol.     The  boiling  point  of  both  of  the  ethers  seemed  to  be 
nearly  the  same,  and  in  both,  in  consequence  of  the  escape  of  an  ethereal  gas, 
an  effervescence  resembling  that  of  ebullition,  was  observed  to  take  place 
at  a  lower  temperature,  than  that  at  which  the  boiling  point  became  sta- 
tionary. 

5676.  From  the  language  of  Liebig  above  quoted,  I  infer  that  previous 
efforts  to  produce  the  methylic  hyponitrous  ether  had  failed.     The  failure 
of  others,  and  my  success,  cannot  excite  surprise,  when  the  difference  of  the 
habitudes  of  wood  spirit  and  alcohol,  with  nitric  acid  and  alcohol,  are  taken 
into  view,  and  the  difference  between  my  process  and  those  followed  in  Eu- 
rope, by  which  more  or  less  nitric  acid  is  brought  into  contact  with  the  spi- 
rit employed.     When  alcohol  is  presented  to  nitric  acid,  a  reciprocal  de- 
composition ensues.    The  acid  loses  two  atoms  of  oxygen,  which,  by  taking 
two  atoms  of  hydrogen  from  a  portion  of  the  alcohol,  transforms  it  into  al- 
dehyde, while  the  hyponitrous  acid  resulting  inevitably  from  the  partial  de- 
oxidizement  of  the  nitric  acid,  unites  with  the  base  of  the  remaining  part  of 
the  alcohol.    But  when  pyroxylic  spirit  is  presented  to  nitric  acid,  this  acid, 
without  decomposition,  combines  with  methyl,  the  base  of  this  hydrate: 
hence,  as  no  hyponitrous  acid  is  evolved,  no  hyponitrite  can  be  produced. 


OF  METHYL  ETHERS.  555 

Thus  in  the  case  of  the  one  there  can  be  no  ethereal  hyponitrite,  in  that  of 
the  other  no  ethereal  nitrate. 

5677.  Oxalated  oxide  of  methyl,  C3  H3  O,  C3  O3,  is  a  white,  transpa- 
rent, and  brilliant  mass,  composed  of  rhomboidal  tables,  which  fuses  at 
123°.8,  and  boils  about  321°.8.     It  is  decomposed  by  water,  and  resolved 
into  hyd rated  oxalic  acid  and  wood  spirit. 

5678.  Formiated  oxide  of  methyl  is  obtained  by  a  process  analogous  to 
that  for  the  formiated  oxide  of  ethyl  (5617),  substituting  pyroxylic  spirit  for 
alcohol.    It  is  lighter  than  water,  and  boils  between  96  and  100°;  its  odour 
suggesting  that  of  acetic  ether. 

Reaction  of  Chlorine,  Iodine,  Cyanogen,  and  Sulphur,  with  Methyl  and 

its  Compounds. 

5679.  Chloride  of  Methyl,  C2H3,  Cl.— This  compound  is  produced  by  the 
reaction  of  chlorohydric  acid  with  hydrated  oxide  of  methyl :  the  rationale 
being  the  same  as  when  this  acid  is  presented  to  a  hydrated  metallic  protox- 
ide.    But  it  is  best  obtained,  as  are  all  the  halogen  compounds  of  methyl, 
by  distilling  the  haloid  salt,  containing  the  halogen  body  with  which  the 
union  is  to  be  made,  with  a  mixture  of  sulphuric  acid  and  hydrated  oxide 
of  methyl:  of  course,  in  the  case  in  point,  chloride  of  sodium  may  be  used. 
Chloride  of  methyl  is  a  colourless  gas,  of  an  ethereal  odour  and  sweet  taste, 
having  the  density  1737.8  by  experiment,  and  1729  by  calculation;  the 
combining  measure  being  four  volumes.     Water  dissolves  2.8  volumes  of 
this  gas  at  60°. 8.     It  is  not  liquefied  by  a  cold  of — 0.4.     It  should  be  re- 
membered that  the  chloride  and  oxide  of  methyl,  are  both  much  more  vola- 
tile than  the  chloride  and  oxide  of  ethyl  (873). 

5680.  Iodide  of  Methyl,  C2  H3!.— This  is  a  colourless  liquid,  which 
inflames  with  difficulty,  and  boils  between  104°  and  122°.     Its  density  is 
2.337  at  69.8. 

5681.  Fluoride  of  Methyl,  C3  H3  F,  is  obtained  by  distilling  sulphated 
oxide  of  methyl  with  fluoride  of  potassium.     It  is  a  colourless  gas,  of  which 
the  density  is  1186  ;  and,  for  the  solution  of  which,  fifteen  volumes  of  water 
are  requisite. 

5682.  Cyanide  of  Methyl,  C3  H3  Cy,  is  an  ethereal  liquid,  insoluble  in 
water. 

5683.  Sulphide  of  Methyl,  C3  H3  S,  is  a  very  limpid  liquid,  of  which 
the  odour  is  extremely  disagreeable.     Its  density  is  0.845  at  69°.8,  and  its 
boiling  point  105°. 8.     The  density  of  its  vapour  is  by  experiment  2115,  by 
theory  2158 ;    its  combining  measure  being  two  volumes.     Sulphide  of 
methyl  is  formed  by  double  decomposition,  when  chloride  of  methyl  is 
transmitted  through  an  alcoholic  solution  of  p^rotosulphide  of  potassium. 

5684.  Sulphydrate  of  the  Sulphide  of  Methyl,  or  Methylic  Mercaptan, 
is  a  colourless  liquid,  lighter  than  water,  which  boils  at  693.8  and  acts  on 
oxides  of  mercury  and  lead  like  sulphydrate  of  sulphide  of  ethyl. 

5685.  Compounds  having  methyl  for  their  radical,  correspond  so  closely 
with  those  in  which  ethyl  sustains  the  'same  character,  that  knowing  the 
history  of  one  class,  it  is  easy  to  imagine  the  properties  of  the  other.     An- 
hydrous metallic  salts  do  not  alter  them,  while  the  hydraled  alkalies  disen- 
gage hydrated  oxide  of  methyl  from  them  with  great  facility. 

5686.  Chlorine  decomposes  the  gaseous  oxide  of  methyl,  forming  chlo- 
rohydric acid,  and  the  following  products,  as  observed  by  M.  Regnault: — 

Monochlorinated  oxide  of  methyl,       -  C3  Ha  Cl  O 

71 


556  ORGANIC  CHEMISTRY. 

Bichlorinated  oxide  of  methyl,  -         C3  H  Cl2  O 

Perchlorinated  oxide  of  methyl,  -         C3  Cl3  O 

5687.  Chlorine  is  absorbed  with  great  avidity  by  hydrated  oxide  of  me- 
thyl, a  heavy  oil  being  generated,  which  has  not  been  well  examined. 

5688.  The  reaction  of  chlorine  with  chloride  of  methyl,  is  the  source  of 
a  series  of  compounds,  in  which,  generally,  the  proportion  of  chlorine  in- 
creases as  the  reaction  is  prolong 


Chloride  of  methyl,      -  C3  H3  Cl 

Monochlorinated  chloride  of  methyl,       -  C2  H3  Cl 

Bichlorinated  do.  (chloroform),  C3  H  Cl3 

Perchlorinated  do.  Ca  Cl  Cl3 

5689.  The  monochlorinated  chloride  of  methyl  has  an  odour  which  is 
very  sharp,  but  is,  in  other  respects,  similar  to  the  oil  of  olefiant  gas.     Dis- 
tilled with  an  alcoholic  solution  of  potash,  a  trifling  precipitate  of  chloride  of 
potassium  is  formed,  and  it  comes  over  unchanged. 

5690.  The  perchloride  of  carbon,  C3  Cl4,  which  is  named,  above,  per- 
chlorinated  chloride  of  methyl,  is  not  altered  by  a  solution  of  sulphydrate 
of  potassium.     It  is  decomposed  by  heat,  yielding  different  chlorides  of  car- 
bon according  to  the  temperature. 

5691.  At  a  low  red  heat,  this  chloride,  C3  Cl4,  appears  to  be  converted 
into  another  chloride  of  carbon,  C3  Cl3,  supposing  the  combining  measure 
of  the  latter  to  be  four  volumes,  its  density  being  4082.    This  new  chloride 
of  carbon  must  therefore  be  isomeric  with  Faraday's  sesquichloride,  C4  Cl8, 
but  of  only  half  the  density.     When  decomposed  at  a  higher  temperature, 
it  gives  small  silky  crystals,  constituting  the  chloride  of  carbon  of  Julin,  C 
Cl.     Lastly,  at  a  bright  red  heat,  the  liquid  chloride  of  carbon,  C4  Cl4,  is 
the  product. 

5692.  Chlorine  acts  readily  upon  the  sulphide  of  methyl,  and  upon  the 
compounds  of  the  oxide  of  methyl  with  acids,  constituting  the  compound 
methylic  ethers.     A  benzoate  and  acetate  of  an  oxychloride  of  formyl  have 
been  produced,  having  the  following  formulae : — 

C3  H  Cl3  O  +  Bz  0.  Ca  H  Cl3  O  +  Ac  O. 

From  a  mixture  of  iodine,  nitric  acid,  and  wood  spirit,  left  to  itself  for  a 
long  time,  yellow  crystals  are  deposited.  Bromine,  under  the  same  circum- 
stances, yields  a  heavy  oily  liquid. 

Of  Formyl  Ethers. 

5693.  Hydrated  oxide  of  methyl,  when  brought  into  contact  with  plati- 
num black  and  atmospheric  air,  is  converted  into  pure  formic  acid,  by  the 
substitution  of  two  atoms  of  oxygen  for  two  of  hydrogen.     The  change  ef- 
fected is,  therefore,  perfectly  similar  to  that  by  which  alcohol  is,  by  the 
same  agent  converted  into  acetic  acid.     Oxide  of  methyl,  formula  C3  H3O 
-f  HO  and  4O,  is  equivalent  to  formic  acid,  C3  HO3  +  3HO.     Hence  the 
inference,  that  formic  acid  contains  a  radical  formyl,  C3H,  to  which  it  has 
the  same  relation  as  acetic  acid  has  to  acetyl:  acetic  acid,  C4  H3  +  O3; 
formic  acid,  C3H  -f  O3  (4019). 

5694.  Formyl  is  the  hypothetical  radical  of  the  following  compounds: — 

Hydrated  oxide  of  formyl  contained  in  methylal,          C3  HO  -f  HO 
Anhydrous  formic  acid,         -  *     C3  HO3 


OF  FORMYL  ETHERS.  557 

Hydrated  formic  acid,          -         -  -  -  C9  HO3  +  HO 

Perchloride  offormyl  (chloroform),  -  -  Ca  H  Cl3 

Perbromide  offormyl,                     -  -  -  C3  H  Br8 

Periodide  offormyl,      -                   -  -         -  -  C3  H  I3 

Of  Methylal,  C8  H8  O,  a  Compound  of  Hydrated  Oxide  of  Formyl,  with 

Oxide  of  Methyl. 

5695.  By  distilling  two  parts  of  wood  spirit  with  two  parts  of  peroxide  of 
manganese,  and  three  parts  of  sulphuric  acid,  diluted  with  three  parts  of 
water,  Dr.  Kane  obtained  a  substance  mixed  with  several  other  bodies, 
which  he  named  formomethylal.     It  was  considered  a  tribasic  formiated 
oxide  of  methyl,  but  was  afterwards  shown  by  Malaguti  to  be  a  mixture  of 
formiated  oxide  of  methyl  and  a  particular  substance  which  he  named  me- 
thylal.     To  purify  the  methylal  from  the  formiated  oxide  of  methyl,  the 
latter  must  be  decomposed  entirely  by  hydrate  of  potash. 

5696.  Methylal  is  an  ethereal,  colourless  liquid,  of  a  very  agreeable  aro- 
matic odour;  which  is  miscible  with  three  parts  of  water,  and  may  be  sepa- 
rated from  that  liquid  by  chloride  of  calcium,  or  hydrate  of  potash.     It  is 
very  inflammable,  and  burns  with  a  white  flame.     The  density  of  methylal 
is  0.8551 ;  its  boiling  point  107°.6;  its  combining  measure  contains  four  vo- 
lumes.    Methylal  may  be  represented  as  a  compound  of  one  atom  of  hy- 
drated  oxide  of  formyl  with  two  atoms  of  oxide  of  methyl  =  C2  HO,  HO 
-f  2C2  H3  O.     Regnault  has  explained  its   formation,  by  supposing  that 
three  atoms  of  oxide  of  methyl,  formed  by  the  action  of  sulphuric  acid  upon 
hyd rated  oxide  of  methyl,  group  together  so  as  to  form  a  single  molecule 
=  C6  H9  O3.    This  molecule,  by  exposure  to  peroxide  of  manganese,  loses 
one  atom  of  hydrogen,  gaining  one  of  oxygen,  so  that  the  compound  C6 
H8  O4  results.     The  formation  of  acetal,  which  corresponds  with  methylal 
in  the  acetyl  series,  is  explained  by  Regnault  in  the  same  manner. 

5697.  Artificial  Oil  of  Ants,  C5  H3  O3  (Stenhouse).— This  name  was 
applied,  by  Dobereiner,  to  an  oil  generated  during  the  preparation  of  formic 
acid.     It  was  obtained  by  Dr.  Stenhouse  in  larger  quantity  than  it  is  pro- 
duced during  the  ordinary  process,  by  distilling  a  mixture  of  equal  weights 
of  oat-meal,  or  saw-dust,  and  sulphuric  acid  diluted  with  its  own  bulk  of 
water.     In  the  process  for  formic  acid,  the  peroxide  of  manganese  cannot 
be  omitted  without  greatly  reducing  the  product;  but  in  the  process  in  ques- 
tion it  should  be  left  out.     When  oil  of  ants  is  purified,  the  taste  and  smell 
are  very  pungent  and  aromatic,  resembling  that  of  oil  of  cassia.     It  burns 
very  readily  with  a  bright  yellow  flame.     Its  density  is  1.1006  at  80°.6; 
its  boiling  point  334°.4.     It  is  soluble  in  water,  but  more  so  in  alcohol  and 
ether.     It  is  decomposed  by  potassium  with  effervescence ;  but  neither  the 
aqueous  nor  the  alcoholic  solution  of  potash  is  affected  by  it. 

Compounds  of  Formyl  with  Chlorine,  Bromine,  Iodine,  and  Sulphur. 

5698.  Protochloride  of  Formyl,  C2  H  Cl. — One  of  the  substances  which 
Regnault  obtained  by  the  reaction  of  chlorine  with  chloride  of  acetyl,  name- 
ly, C4  H3  Cl3,  is  considered  by  Liebig  as  the  protochloride  of  formyl,  its 
atomic  weight  being  divided  by  two. 

5699.  Bichloride  of  Formyl,  C3  H  Cl3. — According  to  Liebig,  of  one  of 
the  combinations,  generated  by  the  reaction  of  chlorine  with  the  chloride  of 
ethyl,  the  formula  is  C4  H3  Cl4.     This  being  divided  by  two,  gives  that  of 
the  bichloride,  as  above  stated. 


558  ORGANIC  CHEMISTRY. 

5700.  Perchloride  of  For  my  I,  Chloroform,  C3  H  Cl3.— This  compound 
may  be  made,  by  exposing  a  mixture  of  chloride  of  methyl,  C2  H3  Cl,  and 
chlorine  to  the  direct  rays  of  the  sun;  by  distilling  chloral  with  barytic 
water,  or  milk  of  lime,  but  more  conveniently  by  distilling  a  dilute  solution 
of  hypochlorite  of  lime,  or  bleaching  salt,  with  acetone,  alcohol,  or  wood 
spirit.     For  this  purpose,  one  part  of  slaked  lime  is  suspended  in  twenty- 
four  parts  of  water,  and  impregnated  with  chlorine  till  the  greater  part  of 
the  lime  is  dissolved.     The  lime  must  be  in  sufficient  excess,  however,  to 
render  the  liquid  slightly  alkaline.     When  the  solution  of  hypochlorite  thus 
made  has  become  clear,  ^T  of  its  volume  of  alcohol  should   be  added. 
The  aggregate,  having  been  allowed  to  rest  for  twenty-four  hours,  is  to  be 
subjected  to  the  distillatory  process,  at  a  gentle  heat,  by  means  of  a  capa- 
cious retort.     The  product,  consisting  of  perchloride  of  formyl,  mixed  with 
alcohol,  being  agitated  with  water,  the  perchloride  separates  as  a  dense  li- 
quid, and  may  be  obtained  perfectly  pure  by  digesting  it  upon  chloride  of 
calcium,  and  rectification  with  concentrated  sulphuric  acid. 

5701.  Perchloride  of  formyl  is  a  colourless,  oily  liquid,  of  an  agreeable 
ethereal  odour,  and  sweetish  taste;  its  density  is  1.480  at  64°.4;  its  boiling 
point,  141°. 44.     It  is  difficult  to  inflame,  but  burns  in  the  flame  of  a  lamp, 
imparting  a  green  colour.     An  alcoholic  solution  of  potash  converts  it  into 
formiate  of  potash,  and  chloride  of  potassium,  on  which  the  name  chloro- 
form is  founded,  Fo  Cl3  and  4  Po  O  =  Po  Fo  O3  and  3  Po  Cl.     The  den- 
sity of  its  vapour  is,  by  experiment,  4200;  by  calculation,  4116;  its  com- 
bining measure  is  4  volumes.     Chloroform  may  be  distilled  from  sulphuric 
acid,  potassium,  or  potash,  without  being  sensibly  altered.     Exposed  with 
chlorine  to  the  direct  rays  of  the  sun,  it  is  decomposed,  and  converted  into 
chlorohydric  acid,  and  a  particular  chloride  of  carbon,  C3  Cl3,  which  boils 
at  172°. 4,  and  of  which  the  density  of  the  vapour  is  5300,  and  combining 
measure  four  volumes.     This  chloride  results  from  the  substitution  of  chlo- 
rine for  the  whole  of  the  hydrogen  and  oxygen  in  formic  acid,  C2  Cl  -f  Cl8; 
while  the  well  known  sesquichloride  of  carbon,  C4  Cl3  -f  Cl3,  is  similarly 
derived  from  acetic  acid. 

5702.  When  the  above  described  chloride  of  carbon  is  made  to  pass 
in  vapour  through  a  porcelain  tube,  at  a  low  red  heat,  it  is  resolved  into 
two  new  chlorides  of  carbon,  of  one  of  which  the  composition  is  C  Cl,  while 
of  the  other  the  composition  is  C  Cl3,  according  to  Regnault. 

5703.  Chlorohydrate  of  the  chloride  of  formyl,  2  C  H  Cl  H  Cl,  is  one 
of  the  products  of  the  reaction  of  chlorine,  with  the  chlorohydrate  of  the 
chloride  of  acetyl. 

5704.  Perhromide  of  formyl,  bromoform,  C3  H,  is  prepared  like  the  per- 
chloride, and  very  analogous  to  it  in  properties.     Its  density  is  2.10.     It  is 
less  volatile  than  the  perchloride,  and  more  easily  decomposed  by  alkalies. 

5705.  Periodide  of  formyl,  idoform,  C3  H  I3,  is  a  yellow,  volatile  sub- 
stance discovered  by  Serullas,  which  is  often  described  as  an  iodide  of  car- 
bon.    To  obtain  it,  an  alcoholic  solution  of  potash  is  added  to  a  solution  of 
iodine  in  alcohol  till  the  last  is  decolorized,  carefully  avoiding  any  excess  of 
the  alkali.     The  alcohol  being  allowed  to  escape  by  gentle  evaporation,  the 
iodide  of  formyl  is  deposited  in  crystals,  which  are  purified  from  iodide  of 
potassium  by  washing  with  pure  water.     This  compound  results  from  the 
reaction  of  one  atom  of  alcohol,  with  six  atoms  of  potash  and  eight  atoms  of 
iodine,  by  which  one  atom  of  periodide  of  formyl,  one  atom  of  formiate  of 
potash,  five  atoms  of  iodide  of  potassium,  and  four  atoms  of  water,  are 
formed. 


OF  XYLITE,  OR  LIGNONE.  559 


1  atom  of  alcohol, 

8  atoms  of  iodine, 
6  atoms  of  potash, 


C4      H6  O    I8  Po8 


1  atom  ofperiodide  of  formyl,       -  -  C3  H         I3 

1  atom  of  formiate  of  potash,  -  Ca  H   O4      Po 

5  atoms  of  iodide  of  potassium,      -         -         -  Is  Po5 

4  atoms  of  water, H4  O4 


C4  H6  O8 18  Po6 

5706.  lodoform  crystallizes  in  brilliant  yellow  plates:  has  a  character- 
istic odour  suggesting  that  of  saffron  ;  is  insoluble  in  water,  but  very  soluble 
in  alcohol,  ether,  and  wood  spirit.     It  sublimes  at  212°,  and  at  248°,  is 
resolved   into  carbon,  iodine,   and  hydriodic  acid.     When   distilled   with 
chloride  of  phosphorus,  or  with  corrosive  sublimate,  it  yields  a  peculiar 
liquid,  of  a  deep  red  colour,  and  a  density  of  1.96,  which  contains  chlorine, 
iodine,  and  formyl. 

5707.  Sulphide  of  formyl,  C2  H3  S3  (Bouchardat),  is  a  liquid  obtained 
by  distilling  one  part  of  iodide  of  formyl,  with  three  parts  of  sulphide  of 
mercury.    By  reaction  with  hydrate  of  potash  it  may  be  converted  into  sul- 
phide of  potassium  and  formiate  of  potash. 

Of  Xylite,  or  Lignone. 

5708.  Having  received  from  Dr.  Ure  a  bottle  of  a  liquid,  which  I  under- 
stood to  be  pure  wood  spirit,  I  subjected  it  to  the  usual  test  of  saturating  it 
with  chloride  of  calcium,  with  which  wood  spirit  reacts  eagerly,  generating 
heat  as  already  mentioned.     I  found,  however,  that  a  colourless  liquid 
separated,  and  formed  a  supernatant  stratum,  in  which  the  chloride  above 
named  did  not  appear  to  be  soluble. 

5709.  When  this  liquid,  and  the  solution  of  the  chloride  in  wood  spirit, 
were  subjected  to  the  distillatory  process,  by  means  of  a  boiling  water  bath, 
only  the  former  come  over,  the  wood  spirit  being  retained  by  the  chloride. 

5710.  It  seems  from  the  account  given  by  Graham,  836,  that  the  liquid 
which  was  distilled,  has  been  examined  by  VViedman  and  Schweiger,  and 
described  under  the  names  at  the  head  of  this  section.     The  formula  as- 
signed to  it  is  C6  H6  Oa£  ;  which,  as  the  admission  of  half  atoms  is  incon- 
sistent with  the  grounds  on  which  the  atomic  theory  is  built,  should  be 
doubled. 

5711.  The  boiling  point  of  xylit  is  about  142°,  its  density  0.816.      The 
density  of  its  vapour  to  that  of  atmospheric  air  as  2177,  by  experiment, 
and  2159  by  calculation.     Pure  xylit  has  an  agreeable,  sharp,  empyreu- 
matic  taste.     It  is  soluble  in  water,  and  burns  with  a  white  flame. 

5712.  Mesiten,  C8  H5  O3,  agreeably  to  the  same  authority,  is  a  liquid 
obtained  by  distilling  equal  parts  of  xylit  and  sulphuric  acid.     Chloride  of 
calcium  is  utterly  insoluble  in  mesiten,  of  which  the  boiling  point  is  145°, 
and  the  density  0.808. 

5713.  Mesite  is  the  name  given  to  a  liquid  which  is  a  concrete  product 
of  the  destructive  distillation  of  wood,  which  gives  birth  to  wood  spirit  and 


560  ORGANIC  CHEMISTRY. 

to  xylit.  Being  less  volatile  than  the  last  mentioned  product,  it  comes  over 
later,  and  hence  it  may  be  isolated.  It  is  formed  also  by  the  reaction  of 
xylite  with  potash  and  potassium. 

5714.  Xylite  Naphtha,  C°  H6  O1*,  results  from  the  reaction  of  hydrate 
of  potash  with  mesite.     It  is  in  its  properties  ethereal ;  being  colourless, 
very  liquid,  and  having  the  odour  of  peppermint.     It  is  but  slightly  soluble 
in  water,  but  very  soluble  in  alcohol,  in  wood  spirit,  xylit  or  ether.    It  boils 
at  230°,  and  burns  with  white  smoky  flame. 

5715.  Xylite  oil  is  produced  from  xylit  naphtha,  by  a  renewed  reac- 
tion with  hydrate  of  potash.     This  oil  has  ethereal  properties. 

5716.  Methal,  C6  H9,  is  a  liquid  generated  by  the  reaction  between  sul- 
phuric acid  and  xylit.     Pyroxanthin,  by  the  distillation  of  crude  wood  spirit 
from  slaked  lime.     These  substances  are  more  of  the  nature  of  an  essential 
oil,  or  camphor,  than  of  that  of  an  ether. 

Of  the  Ethereal  Compounds  of  Mesityl,  or  Mesitylene. 

5717.  The  origin  and  characteristic  properties  of  mesityl  were  stated 
in  the  general  account  of  it,  as  one  of  the  compound  radicals  among  which 
it  stands  distinguished  as  being  one  of  the  few  which  are  capable  of  isola- 
tion.    As  respects  its  properties,  it  may  be  considered  as  an  ether,  per  se. 

5718.  Of  the  Chloride  of  Mesityl,  C6  H5  Cl.— I  give  precedence  to  this 
compound  over  the  oxide,  contrary  to  the  course  pursued  in  the  other  cases; 
as  it  is  only  by  means  of  the  former  that  the  latter  has  been  elaborated. 
To  procure  the  chloride  in  question,  two  parts  of  perchloride  of  phosphorus 
are  mixed  gradually  with  one  of  acetone  in  a  refrigerated  vessel.     On  ihe 
addition  of  water  to  the  resulting  mass,  an  oily  liquid  separates,  which  is 
sufficiently  heavy  to  sink  in  water,  and  which  heat  resolves  into  chlorohy- 
dric  acid  and  mesityl.    This  oily  liquid  is  the  chloride  of  the  last  mentioned 
radical. 

5719.  The  Oxide  of  Mesityl,  C6  H5  O,  is  obtained  by  the  reaction  of 
the  alcoholic  solution  of  the  chloride,  above  described,  with  caustic  potash 
in  excess ;  followed  by  the  addition  of  a  large  quantity  of  water,  an  oily 
liquid  separates,  which,  being  desiccated  by  contact  with  chloride  of  cal- 
cium, is  afterwards  distilled.     Thus  purified,  it  is  a  colourless  liquid,  having 
the  odour  of  peppermint.     It  boils  at  248°,  is  inflammable,  and  burns  with 
a  brilliant  flame,  attended  with  much  smoke. 

5720.  An  impure  Iodide  of  Mesityl  has  been  obtained  by  subjecting 
a  mixture  of  acetone,  phosphorus,  and  iodine,  to  the  distillatory  process 

5721.  Chloride  of  Pteleyle. — When  mesityl  is  impregnated  with  chlo- 
rine, a  sort  of  sub-radical  is  generated,  C6  H3,  having  a  relation  to  mesityl, 
C6  H5,  analogous  to  that  which  acetyl  (3093),  C4  H3,  has  to  ethyl,  C4  H5. 
With  the  sub-radical  thus  generated,  which  was  named  by  its  discoverer, 
Kane,  pteleyle,  the  chlorine  combines,  forming  a  chloride. 

5722.  Of  the  Nitrated  Oxide  of  Pteleyle,  C6  H3  Cl.— When  two  parts 
of  acetone,  and  one  part  of  fuming  nitric  acid,  are  mingled,  a  violent  reac- 
tion ensues.     After  the  resulting  aggregate  has  become  cool,  the  addition  of 
water  causes  the  separation  of  a  mixture  resembling  a  yellow  oil,  which 
consists  of  two  liquids.     The  more  fluid  of  these  has  received  the  name  of 
nitrite  of  the  oxide  of  peteleyle.    It  is  heavier  than  water,  and  is  decomposed 
thereby.     Paper  imbued  with  it  burns  like  prepared  tinder.     It  is  capable 
of  bearing  the  heat  of  212°  without  decomposition,  but  at  a  higher  tempe- 
rature it  explodes  violently ;  hence  it  cannot  be  distilled. 

5723.  Mesitic  Aldehyde,  C*  H3O  -f  HO,  or  the  Hydrated  Oxide  of 


OF  AMYL  ETHERS.  561 

Pteleyle. — Of  the  oily  mixture,  above  described  as  resulting  from  the  reac- 
tion of  fuming  nitric  acid  with  acetone,  mesitic  aldehyde  forms  the  more 
viscid  portion.  It  may  also  be  produced  by  subjecting  a  mixture  of  mesityl 
and  nitric  acid  to  ebullition  as  long  as  any  reaction  takes  place.  From  the 
formula  of  this,  above  given,  it  is  seen  that  it  resembles  aldehyde  in  being 
a  hydrated  oxide  of  a  sub-radical,  obtained  from  another  radical  by  dehy- 
drogenation. 

5724.  Mesitic  aldehyde  is  a  heavy,  viscid,  reddish-yellow  liquid,  with  a 
sweetish  taste  and  penetrating  odour. 

Of  Amyl  Ethers. 

5725.  It  must  appear  from  the  account  given  of  the  hy- 
pothetical compound  radical,  amyl  (4023),  that,  in  certain 
compounds  it  has  been  inferred  to  play  a  part  analogous 
to  that  which  ethyl,  methyl,  and  other  bodies  of  like  kind 
play  in  certain  other  compounds ;  and  that,  especially,  it 
has  been  inferred  that  the  oxide  of  this  radical  exists  in 
the  oil  of  potato  spirit,  in  union  with  water.     This  oil  be- 
ing, therefore,  a  hydrated  oxide  of  amyl,  plays  in  the  com- 
pounds of  amyl,  a  part  like  that  which  alcohol  performs  in 
ethyl  series,  or  wood  spirit  in  the  methyl  series.     Yet  as 
the  oxide  of  amyl  has  not  been  isolated,  we  have  no  amy- 
lic  congener  of  ether,  of  which  the  preparation  and  pro- 
perties, in  an  isolated  state,  are  to  be  described.     Hence, 
the  first  object  to  be  presented  to  the  attention  of  the  stu- 
dent is  the  hydrated  oxide. 

Of  the  Hydrated  Oxide  of  Amyl,  or  Oil  of  Potato  Spirit,  or 
Amylic  Alcohol,  C10  HnO  +  HO. 

5726.  The  congener  of  alcohol,  to  which  the  preceding 
name  has  been  given,  is  generated  during  the  vinous  fer- 
mentation of  an  infusion  of  potatoes;  and  comes  over  to- 
wards the  close  of  the  distillation,  by  which  potato  spirit 
is  separated  from  the  rest  of  the  products  or  residue  of 
that  process,  rendering  the  water,  which  simultaneously 
condenses,  milky.     Being  insoluble  in  this  liquid,  it  sub- 
sides after  some  time,  together  with  a  portion  of  moisture 
and  alcohol.     From  the  latter  of  these  impurities,  it  is  se- 
parated by  agitation  with  water,  and  from  water  by  chlo- 
ride of  calcium  and  redistillation.     To  bring  over  the  pure 
hydrated  oxide  of  amyl,  a  temperature  of  270°  is  required. 

5727.  Potato  spirit  is  a  colourless  liquid,  oily  in  appear- 
ance, with  a  strong  smell,  which  at  first  is  pleasant,  but 
becomes  afterwards  extremely  nauseous.     The  inhalation 


562  ORGANIC  CHEMISTRY. 

of  the  vapour  causes  asthmatic  pains,  cough,  and  even  vo- 
miting. Its  taste  is  very  acrid.  It  burns  with  a  bluish- 
white  flame;  boils  at  270°;  has  a  specific  gravity  of  0.8124 
at  60°.  The  density  of  the  vapour  is  =  3.147,  represent- 
ing four  volumes.  At  4°  it  solidifies,  forming  crystalline 
plates.  It  produces  a  stain  on  paper,  which  disappears 
after  a  short  time;  dissolves  sparingly  in  water,  to  which 
it  communicates  its  odour;  and  is  rniscible  in  all  propor- 
tions with  alcohol,  ether,  fixed  and  volatile  oils,  and  strong 
acetic  acid;  dissolves  sulphur,  phosphorus  and  iodine,  with- 
out being  altered  by  them;  and  may  also  be  mixed  with  a 
solution  of  caustic  potash,  or  soda,  without  change ;  but 
when  heated  with  dry  potash,  hydrogen  is  disengaged,  and 
valerianate  of  potash  is  formed  (Dumas,  Stas).  It  absorbs 
a  large  quantity  of  chlorohydric  acid  gas,  with  evolution 
of  heat.  When  mixed  with  sulphuric  acid,  a  violet  colour 
appears,  and  the  bisulphate  of  oxide  of  amyl  is  produced.* 
When  distilled  with  dry  phosphoric  acid,  a  carbohydrogen 
is  obtained,  to  which  Cahours  has  given  the  name  of  ami- 
lene.  Amylic  alcohol  combines  with  the  bichloride  of  tin, 
forming  a  crystalline  compound,  which  in  the  air,  and 
more  rapidly  when  in  contact  with  water,  is  slowly  re- 
solved into  its  component  parts,  bichloride  of  tin,  and  hy- 
drated  oxide  of  amyl.  See  valerianic  acid  (5283). 

5728.  Acetate  of  Oxide  of  Amyl,  Amylo  Acetic  Ether,  C10  H"O,  C4 
H3  O3  =  Ayl  O,  Ac  O3. — It  is  easily  obtained  by  distilling  a  mixture  of 
two  parts  of  acetate  of  potash,  one  of  hydrated  oxide  of  amyl,  and  one  of 
oil  of  vitriol.     The  product,  after  being  dried  by  means  of  chloride  of  cal- 
cium, and  rectified  along  with  oxide  of  lead,  yields  the  acetate  in  a  state  of 
purity.     It  is  a  colourless  liquid,  having  an  ethereal,  aromatic  odour,  and 
insoluble  in  water.     It  boils  at  248°. 

Of  the  Bromide  and  Iodide  of  Amyl. 

5729.  By  distilling  eight  parts  of  bromine  with  fifteen  parts  of  amylic 
alcohol,  and  one  part  of  phosphorus,  a  bromide  of  amyl,  having  ethereal 
properties,  has  been  obtained ;  and  likewise  an  iodide,  by  the  same  process, 
substituting  iodine  for  bromine.     The  iodide  is  described  as  an  ethereal 
liquid. 

5730.  Of  Glyceryl  and  Cetyl,  there  are  no  ethereal  com- 
pounds. Accordingly,  I  here  terminate  the  chapter  on 
ethers. 


*  A  congener  of  sulphovinic  acid  (5297). 


OF  ANIMAL  SUBSTANCES. 


5731.  Respecting  the  substances  which  come  under  the 
preceding  definition,  I  had  prepared  selections  from  the 
former  edition  of  my  Compendium,  and  from  all  the  other 
more  recent  sources  of  information  within  my  reach,  when 
the  concluding  part  of  the  work  on  Organic  Chemistry,  by 
Liebig  and  Gregory,  fell  into  my  hands.     Finding  it  to  be 
sufficiently  condensed,  I  have  concluded  to  substitute  a 
portion  of  that  work  for  the  matter  which  I  had  prepared. 
My  only  motive  for  publishing  a  text  book,  has  been  my 
inability  to  find  any  work  comprising  descriptions  of  my 
apparatus   and    peculiar   experimental   illustrations,    and 
having  the  requisite  arrangement  and  condensation.     But 
as  the  portion  of  the  work  by  Liebig  and  Gregory,  to 
which  I  have  alluded,  is  deficient  neither  in  arrangement 
nor  in  brevity,  I  deem  it  judicious  to  embody  it  in  this 
Compendium. 

5732.  As  certain  facts  and  hypotheses  adduced  or  sanc- 
tioned by  the  philosopher  of  Giessen  and  his  disciples,  con- 
stitute the  organic  chemistry  now  in  vogue,  and  have  an 
important  bearing  on  physiology,  it  seems  expedient,  so 
far  as  practicable,  to  allow  them  to  be  studied  in  that  au- 
thentic form  which  they  have  been  made  to  assume  by 
Gregory,  the  associate  editor  of  Liebig.     Unfortunately, 
the  organic  chemistry  of  Liebig,  as  translated  by  Gregory, 
is  in  general  too  voluminous  and  abstruse,  to  serve  as  a 
chemical  text  book  for  a  medical  class. 

5733.  I  shall  change  some  names  in  order  to  produce 
an   accordance  with   the   nomenclature   adopted   in  this 
work,  and  to  correct  an  inconsistency  in  using  the  noun 
"nitrogen"  and  yet  employing  the  adjective  " azotized" 
Evidently  either  azot  and  azotized,  or  nitrogen  and  nitro- 
genized,  are  required  by  consistency.* 

*  The  reader  will  not  be  misled  by  some  slight  differences  in  orthography,  as  in 
fibrin  and  fibrine,  legumen  and  legumine 
72 


564  ORGANIC  CHEMISTRY. 

Indifferent  Nitrogenized  Substances  common  to  the  Vegetable  and  Animal 
Kingdoms — Proteine  and  its  Modifications. 

5734.  "  Under  this  head  we  have  to  consider  a  few  very  important  com- 
pounds, which  are  formed  in  the  vegetable  kingdom,  and  are  also  found  to 
constitute  a  large  proportion  of  the  animal  body.     These  are  Albumen,  Fi- 
brine, and  Caseine.     Till  very  recently,  it  was  believed  that  vegetable  al- 
bumen and  fibrine  differed  from  animal  albumen,  fibrine,  and  caseine;  but 
the  recent  researches  of  Mulder  have  shown  this  opinion  to  be  erroneous, 
and  Liebig  has  demonstrated  that  caseine  exists  in  vegetables  with  all  the 
characters  of  that  found  in  milk  (5023). 

5735.  "  The  most  important  step  recently  made  in  advance  in  this  im- 
portant investigation  is  doubtless  the  discovery,  made  by  Mulder,  that  albu- 
men, fibrine,  and  caseine,  are  all  modifications  of  one  compound,  to  which 
he  has  given  the  name  of  Proteine  (from  Trganva,  I  take  the  first  place),  as 
being  the  original  matter  from  which  all  these  varieties  are  derived. 

5736.  "Proteine  is  composed  of  carbon,  hydrogen,  nitrogen,  and  oxy- 
gen ;  and  Mulder  has  shown,  that  two  analyses  of  proteine  do  not  differ 
more  than  analyses  of  fibrine,  albumen,  or  caseine  do,  either  from  one  ano- 
ther, or  from  that  of  proteine,  as  far  as  regards  these  elements.     He  has 
further  shown,  that  all  of  these  bodies,  whether  they  contain  proteine 
ready  formed  or  not,  readily  yield  it  when  acted  on  by  alkalies.     While 
proteine,  however,  contains  no  inorganic  matter,  albumen,  fibrine,  and  ca- 
seine each  contain  small  but  essential  quantities  of  mineral  substances,  such 
as  sulphur,  phosphorus,  potash,  soda,  common  salt,  and  phosphate  of  lime. 
Further,  it  has  been  established  by  the  still  more  recent  researches  of  the 
school  of  Giessen,  that  animal  and  vegetable  albumen,  animal  and  vegeta- 
ble fibrine,  and  animal  and  vegetable  caseine,  are  respectively  identical  in 
every  particular.    We  may  therefore  assume  that  there  is  but  one  albumen, 
one  fibrine,  and  one  caseine ;  and  it  is  convenient  to  consider  them  all  as 
compounds  of  proteine  with  small  proportions  of  inorganic  matter  (5023). 

5737.  "Proteine. — When  animal  or  vegetable  albumen,  fibrine,  or  ca- 
seine, are  dissolved  in  a  moderately  strong  solution  of  caustic  potash,  and 
the  solution  heated  for  some  time  to  120°,  the  addition  of  acetic  acid  causes 
a  gelatinous  precipitate,  which  has  the  same  composition  and  properties, 
from  whichever  of  these  compounds  it  has  been  prepared.     When  well 
washed  and  dried,  this  is  proteine. 

5738.  "It  forms  a  yellowish  brittle  mass,  insoluble  in  water  and  alcohol. 
Mulder  has  analyzed  proteine  from  animal  and  vegetable  albumen,  from 
fibrine  and  from  cheese,  or  caseine;  and  Scherer  has  analyzed  proteine 
from  animal  albumen  and  fibrine,  from  the  crystalline  lens,  from  hair,  and 
from  horn.     The  results  from  all  these  analyses  agree  best  with  the  for- 
mula C48  H38  N6  O14  (Liebig) ;  Mulder  first  gave  the  formula  C40  H31  N5  O13. 
The  symbol  of  proteine  is  Pr. 

5739.  "  Proteine  combines  with  both  acids  and  bases :  with  diluted  sul- 
phuric acid  it  forms  sulphoproteic  acid,  Pr  +  SO3;  with  diluted  chlorohy- 
dric  acid,  another  acid,  Pr  -f-  2HC1.     When  chlorine  is  passed  through  a 
solution  containing  proteine,  white  flocks  are  deposited,  which  Mulder  calls 
chloroproteic  acid,  Pr  +  CIO3.     (Mulder.) 

5740.  "When  proteine,  or  any  of  its  modifications,  is  digested  in  nitric 
acid,  a  yellow  compound  is  formed,  along  with  oxalic  acid  and  ammonia. 
The  yellow  compound  is  called  xanthoproteic  acid,  and  its  formula  is  C34 


OP  ANIMAL  SUBSTANCES.  565 

H34  N4  O13,  2HO.     It  seems  to  combine  both  with  acids  and  bases.     Its 
salts  with  bases  dissolve  with  a  red  colour.     (Mulder.) 

5741.  "When  boiled  with  an  excess  of  caustic  potash,  proteine,  albumen, 
&c.,  are  decomposed,  yielding,  besides  ammonia  and  carbonic  and  formic 
acids,  three  azotized  products,  protide,  erythroprotide,  and  leucine.     Ery- 
throprotide  is  a  reddish-brown  amorphous  mass;  and  its  formula,  in  the 
compound  it  forms  with  oxide  of  lead,  is  said  to  be  C13  H8  NO5.     Protide 
is  a  yellowish,  soluble,  uncrystallizable  substance,  and  its  formula  is  C13  Ei9 
NO4.     Leucine  crystallizes  in  shining  scales,  which  sublime  unaltered  at 
338°.     Its  formula  is  C13  H13  NO4.     With  one  atom  of  hydrated  nitric 
acid  it  yields  nitroleucic  acid,  which  forms  crystallizable  salts.     Leucine 
may  also  be  formed  by  the  action  of  sulphuric  acid  on  proteine  or  its  com- 
pounds.    (Mulder.) 

5742.  "According  to  Mulder,  proteine  combines  with  the  oxides  of  lead 
and  silver  in  the  proportion  of  ten  atoms  to  one  of  the  base :  and  the  same 
amount  of  proteine  is  contained  in  albumen  and  fibrine;  the  former  being 
lOPr  +  S3  +  P£,  the  latter  lOPr  +  S4  +  P£. 

5743.  "According  to  Liebig,  (Animal  Chemistry,  p.  106,)  proteine  is 
produced  by  vegetables  alone,  and  cannot  be  formed  by  animals ;  although 
the  animal  organism  possesses  the  power  of  converting  one  modification  of 
proteine  into  another,  fibrine  into  albumen,  or  vice  versa,  or  both  into  ca- 
seine,  &c.     In  this  point  of  view  the  vegetable  forms  of  proteine,  vegetable 
albumen,   fibrine,  and  caseine,   become  signally  important,  as   the  only 
sources  of  proteine  for  animal  life,  and  consequently  of  nutrition  strictly  so 
called,  that  is,  the  growth  in  mass  of  the  animal  body. 

5744.  " Proteine  is  never  found,  as  such,  in  nature;  but  occurs  in  the 
shape  of  albumen,  fibrine,  or  caseine,  both  in  vegetables  and  animals,  and 
in  some  other  forms  in  the  animal  body. 

Modifications  of  Proteine. 

5745.  "  Albumen. — This  important  substance  forms  the  white  of  eggs, 
and  occurs  in  large  quantity  in  the  blood.     It  is  also  found  in  other  animal 
fluids,  and  in  most  of  the  animal  solids. 

5746.  "It  occurs  also  in  many  vegetable  juices,  and  in  many  seeds,  such 
as  nuts,  almonds,  &c.     From  whatever  source  it  is  obtained,  its  properties 
are  the  same. 

5747.  "Albumen  is  naturally  soluble  in  water,  and  is  found  dissolved  in 
the  serum  of  the  blood,  and  in  vegetable  juices.     The  white  of  eggs  is  quite 
soluble ;  and  the  albumen  of  wheat  flour  also  dissolves  in  water,  if  it  have 
been  purified  without  the  application  of  heat.     But  when  it  has  once  been 
heated  to  160°,  it  becomes  insoluble;  and,  if  previously  dissolved,  a  heat  of 
158°  causes  the  dissolved  albumen  to  coagulate,  and  the  coagulum  is  inso- 
luble in  water.     Hence  albumen  is  described  in  two  states,  the  soluble  and 
the  coagulated. 

5748.  "If  white  of  egg,  or  serum  of  blood,  be  dried  up  at  120°,  the  resi- 
due is  soluble  albumen  in  an  impure  state.     It  may  be  purified  by  being 
well  washed  with  cold  ether  and  alcohol,  which  remove  fat,  salts,  and  other 
foreign  matters. 

5749.  "Dry  soluble  albumen,  when  placed  in  water,  first  swells  up,  and 
then  forms  a  glairy  fluid.     This  solution  is  coagulated  by  heat,  by  acids, 
by  alcohol,  by  creosote,  &c.     The  acids  which  do  not  coagulate  albumen 
are  acetic  acid,  phosphoric  and  pyrophosphoric  acids.     The  coagulated  al- 


566  OP  ORGANIC  CHEMISTRY. 

bumen  dissolves,  with  the  aid  of  heat,  in  strong  hydrochloric  acid,  pro- 
ducing a  purple  solution.  This  reaction  takes  place  with  all  the  modifica- 
tions of  proteine,  and  indicates  a  great  similarity  of  constitution  among 
them. 

5750.  "The  solution  of  albumen  is  also  coagulated  or  precipitated  by  the 
acetate  of  lead  and  the  bichloride  of  mercury,  and  by  infusion  of  galls ;  also 
by  the  ferrocyanide  of  potassium  if  acetic  acid  be  added.     From  the  insolu- 
bility of  the  precipitate  with  bichloride  of  mercury,  white  of  egg,  beat  up 
with  water,  is  used  as  an  antidote  to  that  poison.     One  egg  combines  with 
about  four  grains  of  corrosive  sublimate. 

5751.  "The  precipitates  formed  by  acids  are  compounds  of  albumen 
with  the  acid  employed.     They  are  soluble  in  pure  water,  but  quite  insolu- 
ble in  diluted  acids. 

5752.  "  Coagulated  albumen  is  quite  insoluble  in  water,  but  is  readily 
dissolved  by  caustic  alkalies,  which  it  even  neutralizes.     These  compounds 
yield  insoluble  albuminates  with  the  metallic  salts. 

5753.  "Coagulated  albumen,  when  acted  on  by  hydrochloric  acid,  yields 
from  one  to  two  per  cent,  of  phosphate  of  lime;  and  soluble  albumen  ap- 
pears to  possess  the  property  of  dissolving  that  salt,  a  property  which  ena- 
bles the  blood  to  convey  to  the  bones  their  earthy  part,  and  probably  also 
to  carry  away  that  which  is  found  in  the  urine. 

5754.  "  When  albumen  is  analyzed,  it  yields  the  same  results  as  pro- 
teine, in  regard  to  carbon,  hydrogen,  nitrogen,  and  oxygen;  but  it  contains 
less  than  one  per  cent,  of  sulphur  and  phosphorus  together,  which  are  ab- 
sent in  proteine.    According  to  Mulder,  it  is  lOPr  -}-  S3  +  P£  ;  but  we  have 
no  means  of  determining  with  accuracy  such  small  proportions  of  sulphur 
and  phosphorus,  and  it  is  therefore  preferable  to  represent  albumen  as  pro- 
teine with  certain  small  indeterminate  proportions  of  sulphur  and  phos- 
phorus.    When  burned,  it  also  leaves  ashes,  which  contain  phosphate  of 
lime  and  alkaline  salts. 

5755.  "To  prove  the  presence  of  unoxidized  sulphur  in  albumen,  dis- 
solve it  in  potash,  then  add  acetate  of  lead  as  long  as  the  precipitate  formed 
is  redissolved,  and  heat  the  solution  to  the  boiling  point.     It  instantly  be- 
comes black  by  the  separation  of  sulphuret  (sulphide)  of  lead.     The  same 
test  applies  to  fibrine  and  caseine.    (Liebig.)     It  is  not  known  in  what  state 
the  phosphorus  exists  in  albumen,  after  phosphate  of  lime  has  been  sepa- 
rated.    The  fetid  smell  of  putrefying  albumen,  indicates  distinctly  the  pre- 
sence of  sulphuretted  hydrogen  (sulphydric  acid)  among  the  products  of  its 
putrefaction. 

5756.  "  When  the  juice  of  many  vegetables,  after  being  separated  from 
the  coagulum  or  deposit  which  spontaneously  forms  in  it,  and  which  is 
vegetable  fibrine,  is  heated,  a  new  coagulum  is  formed,  which  is  vegetable 
albumen.     When  nuts,  almonds,  and  similar  seeds,  are  freed  from  their 
oil  by  pressure,  the  residue  is  chiefly  vegetable  albumen  in  the  soluble 
form.     It  is,  in  every  respect,  identical  with  the  albumen  of  eggs  and  of 
blood. 

5757.  "  Albumen  must  be  considered  as  the  true  starting  point  of  all  the 
animal  tissues.    This  appears  from  the  phenomena  of  incubation,  where  all 
the  tissues  are  derived  from  the  albumen  of  the  white  and  of  the  yolk,  which 
contains  albumen  also,  with  the  aid  only  of  the  air,  of  the  oily  matter  of  the 
yolk,  and  of  a  certain  proportion  of  iron,  also  found  in  the  yolk.    It  is  clear 
from  this,  that  albumen  may  pass  into  fibrine,  caseine,  membranes,  horn, 
hair,  feathers,  &c. 


OF  ANIMAL  SUBSTANCES.  567 

5758.  "  Fibrine. — This  modification  of  proteine  occurs,  like  albumen,  in 
two  forms,  dissolved  and  coagulated.     The  former  is  found  in  fresh-drawn 
blood  and  in  fresh-drawn  vegetable  juices,  from  both  of  which  it  coagulates 
spontaneously  on  standing.     In  the  coagulated  state  it  is  found  in  muscular 
fibre,  and  in  the  gluten  of  wheat  flour  and  the  seeds  of  the  cerealia  gene- 
rally. 

5759.  "  The  characters  of  insoluble  or  coagulated  fibrine  closely  resem- 
ble those  of  coagulated  albumen.     With  strong  acetic  acid  it  forms  a  jelly, 
which  may  be  dissolved  by  boiling  water,  and  is  precipitated  by  ferrocyan- 
ide  of  potassium.     It  is  similarly  acted  on  by  other  acids;  and,  like  albu- 
men, dissolves  in  alkalies,  which  it  neutralizes.     It  gives  a  purple  solution 
with  strong  hydrochloric  acid. 

5760.  "When  fresh  blood  is  allowed  to  stand,  the  fibrine  dissolved  in  it 
coagulates  very  soon,  and  forms  the  clot,  which,  however,  is  coloured  by 
the  globules  of  the  blood ;  but  if  the  blood  be  stirred  with  a  stick  while  co- 
agulating, the  fibrine  adheres  to  the  stick  in  grey  stringy  masses,  which 
dry,  like  albumen,  into  a  horny  matter.     Like  albumen,  it  contains  sulphur 
and  phosphorus,  and  its  ashes  contain  phosphate  of  lime.     It  contains  less 
sulphur,  however,  than  albumen.* 

5761.  "As  albumen,  during  incubation,  passes  into  fibrine,  so  fibrine,  in 
the  animal  body,  passes  into  albumen  ;  for  example,  in  the  case  of  an  ani- 
mal fed  on  muscular  fibre,  whose  blood  contains  the  usual  proportion  of  al- 
bumen.    Nay,  Denis  has  shown  that  the  fibrine  of  venous  blood,  by  diges- 
tion with  a  solution  of  nitre,  is  dissolved,  and  acquires  the  characters  of 
albumen,  being  coagulated  by  heat  and  by  acids.     Scherer  has  shown  that 
the  fibrine  of  arterial  blood  does  not  undergo  this  change,  nor  that  of  the 
buffy  coat,  nor  even  venous  fibrine  after  exposure  to  the  air  for  some  time. 
Hence  he  concludes  that  it  is  rendered  incapable  of  dissolving  by  the  action 
of  oxygen,  and  that  the  fibrine  of  venous  and  of  arterial  blood  are  thus  dis- 
tinct; the  former  being  soluble,  the  latter  coagulated. 

5762.  "  He  found  that  the  above  mentioned  solution  of  venous  fibrine 
in  nitre,  when  exposed  to  the  air,  deposited  an  insoluble  matter,  identical 
with  arterial  fibrine.     He  also  observed,  that,  after  being  boiled  for  a  short 
time,  venous  fibrine  became  insoluble,  and  had  lost  the  property,  possessed 
by  it  when  fresh,  of  absorbing  oxygen  and  giving  off  carbonic  acid. 

5763.  "  The  fibrine  which  spontaneously  coagulates  from  certain  vege- 
table juices,  such  as  those  of  carrots,  turnips,  and  beet-root,  and  that  con- 
tained in  the  gluten  of  wheat  flour,  are  identical  in  properties  and  composi- 
tion with  animal  fibrine. 

5764.  "  Fibrine,  both  animal  and  vegetable,  is  a  most  important  element 
of  nutrition,  and  yields,  in  the  animal  body,  albumen,  caseine,  and  the  tis- 
sues derived  from  them. 

5765.  "  Caseine. — This,  the  third  important  modification  of  proteine,  is 
found  in  milk,  and  constitutes  that  ingredient  which  is  neither  coagulated 
spontaneously,  like  fibrine;  nor  by  heat,  like  albumen;  but  by  the  action 

*  To  determine  the  quantity  of  fibrine  in  blood,  M.  Simon  receives  it  in  a  flask 
containing  little  bits  of  metal  first  weighed  without  the  flask,  then  with  this  reci- 
pient;  and  after  the  introduction  of  the  blood,  the  flask  and  its  contents  are  weighed 
together.  On  agitating  the  flask,  the  bits  of  metal  become  coated  with  fibrine.  Sub- 
sequently they  are  washed  with  water,  dried,  and  weighed.  By  these  means,  guard- 
ing  against  any  deficit,  the  weight  of  the  fibrine  may  be  deduced.  Agreeably  to 
the  same  authority,  menstrual  blood  contains  no  fibrine."  Berzelius'  Report  1841 
page  263. 


568  ORGANIC  CHEMISTRY. 

of  acids  alone.  Cheese,  made  from  skimmed  milk  and  well  pressed,  is 
nearly  pure  caseine.  A  substance  quite  identical  is  found  abundantly  in 
the  seeds  of  leguminous  plants,  and  was  formerly  called  Legumine.  Liebig 
has  recently  shown  that  legumine  is  nothing  but  caseine;  and,  from  what- 
ever source,  it  is  found  to  be  a  compound  of  proteine.  Thus  its  analysis 
gives  the  same  results  as  those  of  fibrine  and  albumen  for  the  four  organic 
elements  ;  and  it  differs  from  these  bodies  in  containing  no  free  phosphorus. 
Its  ashes  are  very  rich  in  phosphate  of  lime  and  in  potash ;  and  in  this 
point  also  animal  and  vegetable  caseine  agree. 

5766.  "  Coagulated  caseine  is  generally  a  compound  of  caseine  with  the 
acid  employed  to  coagulate  it.     When  milk,  on  standing  long,  coagulates, 
it  is  found  to  contain  free  lactic  acid,  some  of  which  by  combining  with  the 
caseine  has  caused  the  precipitate.     When  sulphuric  acid  is  used,  the  coa- 
gulum  is  sulphate  of  caseine ;  which,  when  the  acid  is  removed  by  carbon- 
ate of  lead,  yields  pure  caseine. 

5767.  "  When  dry,  caseine  thus  prepared  is  like  gum.     It  is  not  readily 
dissolved  by  water,  and  never  forms  a  clear  solution.     It  is  precipitated  by 
acetic  acid,  but  in  other  respects  resembles  a  solution  of  albumen,  except  that 
it  is  not  coagulated  by  heat.     When  milk  is  placed  in  contact  with  rennet^ 
which  is  the  lining  membrane  of  a  calf's  stomach,  it  is  coagulated.    Liebig 
has  shown,  that,  unless  the  membrane  be  in  a  state  of  decomposition,  this 
change  does  not  take  place ;  and  it  probably  depends  on  the  formation,  under 
the  fermenting  influence  of  the  membrane,  of  sufficient  lactic  acid  to  neu- 
tralise the  alkali  of  the  milk,  and  thus  coagulate  the  caseine.     When  sweet 
milk  or  cream  is  used,  the  cheese  contains  much  butter  besides  the  caseine. 

5768.  "  When  milk  is  heated  in  an  open  vessel,  a  pellicle  is  formed,  which, 
if  removed,  is  continually  renewed,  and  is  insoluble.     It  is  owing  to  the 
action  of  oxygen,  for  it  does  not  form  in  an  atmosphere  of  carbonic  acid. 
(Scherer.) 

5769.  "  When  peas,  beans,  or  lentils  are  softened  in  cold  water,  then 
ground  with  that  fluid,  and  the  mass  further  diluted,  and  strained  through 
a  fine  sieve,  there  passes  through  a  solution  of  caseine  in  which  starch  is 
suspended.     When  the  starch  has  settled,  the  supernatant  liquid  is  a  solu- 
tion of  caseine,  which  is  always,  like  milk,  turbid,  partly  from  suspended 
fat,  partly  from  the  gradual  action  of  the  air  on  the  dissolved  caseine,  lactic 
acid  being  slowly  formed,  which  causes  a  gradual  separation. 

5770.  "  This  solution  has  all  the  characters  of  skimmed  milk ;  it  is  coagu- 
lated by  acids,  not  by  heat,  and  forms  a  pellicle  when  heated.     It  also  co- 
agulates after  long  standing  from  the  formation  of  lactic  acid ;  and,  when 
the  coagulum  putrefies,  the  odour  is  exactly  that  of  putrid  cheese.  (Liebig.) 

5771.  "The  ashes  of  soluble  caseine,  whether  animal  or  vegetable,  are 
very  strongly  alkaline ;  and   there  is  reason   to  believe  that  the  potash 
found  in  the  ashes  had  served,  by  combining  with  the  caseine,  to  render  it 
soluble. 

5772.  "  Caseine  occurs  also  in  the  oily  seeds,  such  as  almonds,  nuts,  &c. 
along  with  albumen,  and  must  be  considered  as  a  very  important  element 
of  nutrition. 

5773.  "  Scherer,  by  acting  on  the  serum  of  blood  with  water  and  a  little 
caustic  potash,  obtained  a  neutral  solution,  which  no  longer  coagulated  by 
heat,  but  formed  a  pellicle  like  milk.     As  this  pellicle  appeared  identical 
with  that  from  milk,  the  experiment  seems  to  prove  the  conversion  of  albu- 
men into  caseine. 

5774.  "Mulder  considers  caseine  to  be  lOPr-fS;  but  pure  caseine  is 


OF  ANIMAL  SUBSTANCES.  569 

not  known,  and  caseine,  as  it  usually  occurs,  contains  6.5  per  cent,  of  in- 
organic matter,  chiefly  phosphate  of  lime  and  potash.  There  is  no  doubt, 
however,  that  the  organic  elements  of  caseine  are  united  in  the  same  pro- 
portion as  those  of  proteine,  albumen,  and  fibrine ;  while,  like  the  two  latter, 
it  yields  a  purple  solution  when  heated  with  strong  chlorohydric  acid.  The 
action  of  milk,  also,  in  the  nutrition  of  young  animals  proves  that  caseine 
is  capable  of  conversion  into  albumen  and  fibrine ;  while  the  production  of 
milk  in  an  animal  fed  on  albumen  or  fibrine,  or  both,  shows  that  these  bo- 
dies may  be  reconverted  into  caseine. 

5775!  «« We  may  exhibit  the  connection  between  these  substances  as 
follows.  Pr  represents  proteine,  C48H38N6O14.  P  and  S  represent,  not 
equivalents,  but  only  small  indeterminate  quantities,  of  phosphorus  and 
sulphur. 

Albumen  is       .       Pr-f  Sa+P-f- salts. 

Fibrine  is          .       Pr+S  +P-f  salts. 

Caseine  is         .       Pr-j-S  -f  salts. 

5776.  "  We  can  thus  easily  understand  the  formation  of  any  one  of  them 
from  proteine,  or  the  conversion  of  one  into  the  other.     Albumen,  losing 
half  its  sulphur,  becomes  fibrine;  and  fibrine,  losing  its  phosphorus,  be- 
comes caseine :  but  the  salts  are  not  exactly  the  same,  nor  in  the  same  pro- 
portions in  all  the  three  cases. 

The  Blood,. 

5777.  "  This  important  fluid,  from  which  alt  parts  of  the  body  are  form- 
ed, possesses  very  remarkable  properties.     In  the  veins  it  is  dark-coloured, 
in  the  arteries  bright  red.     When  drawn,  it  presently  forms  a  red  clot, 
composed,  as  we  have  seen,  partly  of  fibrine,  while  the  serum  contains  a 
large  quantity  of  albumen. 

5778.  "  The  colour  of  the  clot  is  owing  to  a  compound  which  has.  been 
called  Hcematosine,  which  has  many  properties  in  common  with  albumen ; 
but  the  globules  of  the  blood,  in  which  the  colour  naturally  resides,  are  not 
composed  of  hsematosine  alone,  but  contain  another  albuminous  compound, 
to  which  the  name  of  (rlobuline  has  been  given.    It  is  probable  that  neither 
of  these  compounds  is  known  in  a  state  of  purity. 

5779.  "  To  obtain  them,  blood  is  well  stirred  to  separate  the  fibrine,  and 
mixed  with  six  volumes  of  a  saturated  solution  of  sulphate  of  soda,  in  which 
the  globules  are  insoluble.     They  are  then  boiled  with  alcohol  acidulated 
with  sulphuric  acid,  which  dissolves  a  sulphate  of  hsematosine,  and  leaves  a 
sulphate  of  globuline.     The  red  alcoholic  solution  is  mixed  with  carbonate 
of  ammonia,   which  separates  the  sulphuric  acid  as  sulphate  of  ammonia, 
along  with  a  little  globuline.    The  filtered  solution,  being  evaporated,  leaves 
hsematosine  as  a  dark  brownish  red  mass. 

5780.  "  Hsematosine  thus  prepared  is  insoluble  in  water,  alcohol,  and 
ether,  but  forms  red  solutions  with  alcohol,  to  which  either  acids  or  alkalies 
are  added.    Its  ashes  contain  iron,  but  Liebig  and  Scherer  have  shown  that 
the  red  colour  does  not  depend  on  that  metal,  which  may  be  removed  either 
from  the  globules,  or  from  ha3matosine,  by  strong  sulphuric  acid,  without 
destroying  the  red  colour;  and  in  this  experiment  the  red  matter  left  gives  a 
white  ash,  free  from  iron.     Iron,  however,  is  essential  to  the  blood,  and  is 
consequently  supplied  in  the  food.     The  ashes  of  almost  all  vegetables  con- 
tain a  little  iron;  flesh,  of  course,  does  so,  as  it  is  mixed  with  blood;  and 
the  yolk  of  egg  is  found  to  contain  an  oily  matter,  of  which  iron  is  an  in- 
gredient. 


570  OF  ORGANIC  CHEMISTRY. 

5781.  "  Globuline  forms  the  principal  part  of  the  blood-globules.    It  has 
not  been  obtained  in  a  pure  state,  but  has  all  the  characters,  as  well  as  the 
composition,  of  dissolved  albumen.     The  compound  with  sulphuric  acid 
above  mentioned,  is  grey,  or  white,  and  was  found  to  contain  four  atoms 
of  sulphuric  acid  and  one  of  proteine. 

5782.  "Besides  albumen,  the  serum  of  the  blood  contains  fat  and  saline 
matters.     When  heated,  the  albumen  coagulates,  and  floats  in  a  watery 
liquid  called  the  Serosity.     This  contains  common  salt,  sulphates,  phos- 
phates, and  carbonates.     The  blood  probably  also  contains  the  ingredients 
of  the  secretions  and  excretions,  such  as  bile  and  urine;  but  these  are  in  so 
small  a  proportion,  that,  except  in  cases  of  disease,  it  is  hardly  possible  to 
detect  them.    The  fatty  matter  in  blood  is  obtained  by  drying  up  the  serum 
and  digesting  with  ether.     It  consists  of  the  usual  animal  fats,  and  is  said 
likewise  to  contain  cholesterine,  or  the  fat  of  bile. 

5783.  "  The  following  table  gives  the  results  of  two  careful  analyses  of 
blood  by  Lecanu : 

Human  blood. 

Water 780.145  785.590 

Fibrine .  2.100  3.565 

Colouring  matter  (haematosine  and  globuline)         -            -  133.000  119.626 

Albumen        -                                                                             .  65-090  69.415 

Crystalline  fat            -            -  2.430  4.300 

Oily  matter    -                         .  1.310  2.270 

Extractive  matter  (soluble  in  water  and  alcohol)     -  1.790  1.920 

Albuminate  of  soda                                          -            -            -  1.265  2.010 

Alkaline  chlorides,  carbonates,  phosphates,  and  sulphates  8.370  7.304 

Carbonates  of  lime  and  magnesia,  phosphates  of  lime,  >  «  i  no  1  414 

magnesia,  and  iron,  peroxide  of  iron 

Loss                                       -           -           -  2.400  2.586 

1000.000  1000.000 


5784.  "  It  is  obvious,  that,  as  the  blood  is  chiefly  composed  of  compounds 
of  proteine,  its  composition  cannot  be  very  different  from  that  of  proteine  or 
its  modifications.     In  fact,  dried  blood,  when  analyzed,  yields  the  formula 
C48H39N6O15,  which  is  proteine,  C«  H36  N6  O14  +  HO  +  Ha.    (Playfair 
and  Boeckmann.)     This  excess  of  hydrogen  is  probably  derived  from  the 
presence  of  fat. 

5785.  "  From  the  blood,  that  is,  from  the  compounds  of  proteine  in  the 
blood,  are  derived  all  the  animal  tissues.     Some  of  these  are  compounds  of 
proteine,  others  have  no  longer  the  characters  of  such  compounds ;  but  in 
all  cases  they  are  derived  from  proteine. 

5786.  "  Muscular  tissue,  or  muscular  fibre,  is  composed  chiefly  of 
fibrine,  mixed  however  in  the  ordinary  state  with  blood,  membranes,  ner- 
vous matter,  and  fat.     Dried  flesh,  when  analyzed,  gave  the  same  formula 
as  dried  blood,  namely,  C48  H39  N6  O15.     (Playfair  and  Boeckmann.) 

5787.  "  When  flesh  is  acted  on  by  hot  water,  there  is  dissolved  a  quan- 
tity equal  to  17  per  cent,  of  its  weight.     The  dissolved  matter  contains  the 
salts  of  flesh,  and  several  organic  matters  probably  produced  in  the  opera- 
tion, the  nature  of  which  is  very  little  known.     One  of  these  has  been  de- 
scribed unde.r  the  name  of  Osmazome,  and  is  supposed  to  give  to  soup  and 
dressed  meat  their  peculiar  flavour :  but  osmazome  is  certainly  not  a  pure 
substance,  as  at  present  known  ;*  and  the  whole  subject  of  the  changes 

*  In  other  words,  osmazome  is  not  a  definite  compound  to  which  any  formula  can 
be  assigned,  but  probably  a  mixture  of  substances  not  yet  distinguished. 


OF  ANIMAL  SUBSTANCES.  571 

produced  in  food  by  cooking  is  understood  to  be  under  investigation  by 
Liebig. 

5788.  "  Gelatinous  tissue. — Under  this  name  are  included  the  organic 
tissue  of  the  bones,  that  of  tendons  and  ligaments,  the  cellular  tissue,  the 
skin,  and  the  serous  membranes.     All  these  substances  dissolve  by  long- 
continued  boiling  in  water,  and  the  solution  on  cooling  forms  a  jelly.     The 
coarser  forms  of  gelatine,  from  hoofs,  hides,  &c.  are  called  Glue;  that  from 
skin  and  finer  membranes  is  known  as  Size;  and  the  purest  gelatine,  from 
the  air-bladders  and  other  membranes  offish,  is  called  Isinglass.    Gelatine 
does  not  exist  as  such  in  the  animal  tissues,  but  is  formed  by  the  action  of 
boiling  water.* 

5789.  "  Gelatine  is  soluble  in  water,  and  the  hot  concentrated  solution 
forms  a  jelly  on  cooling.    It  is  precipitated  by  tannic  acid,  forming  an  inso- 
luble compound,  which  forms  the  chief  part  of  leather.     Leather  is  made 
by  steeping  softened  skins  in  a  strong  infusion  of  oak-bark,  catechu,  or 
other  astringent  vegetables  containing  tannic  acid.     Skins  are  prepared  in 
other  ways,  yielding  different  kinds  of  leather,  such  as  tawed  leather,  wash- 
leather,  &c.;  but  the  process  of  tanning  depends  on  the  action  of  tannic 
acid  on  the  gelatinous  tissue. 

5790.  "  Gelatine,  when  acted  on  by  sulphuric  acid,  yields  gelatine  su- 
gar, or  glycicoll,  C8  H7  N3  O5, 2HO.     When  treated  with  potash,   it   is 
said  to  yield  glycicoll  and  leucine.     Glycicoll  unites  with  oxide  of  lead, 
forming  a  compound,  C8  H7  N3  O5, 2PbO.  (Mulder.)    It  also  combines  with 
nitric  acid,  forming  a  compound  acid,  C8  H7  N3  O5  -f  2NO5  -f  4HO,  which 
crystallizes,  and  forms  double  salts  with  bases.     That  with  lime  is  CaO,C8 
H7N3O  +  2(CaO,  NO5). 

5791.  "According  to  Scherer,  the  composition  of  gelatinous  tissue  is 
represented  by  the  formula  C48  H41  N7£  O18,  or  doubled,  C96  H83  N15  O38 ; 
which  latter  formula  represents  2  atoms  proteine  -f-  3NH3,  -f-HO  -f  O7. 

5792.  "  Although  gelatine  is  thus  nearly  related  to  proteine,  and  is  doubt- 
less formed  from  one  or  other  of  its  modifications,  yet  it  has  none  of  the 
characters  of  a  compound  of  proteine.     It  does  not  yield  proteine  when 
acted  on  by  potash,  and  it  does  not  produce  a  purple  colour  with  hydrochlo- 
ric acid.     It  therefore  no  longer  contains  proteine. 

5793.  "  This  accounts  for  the  fact,  that  animals,  fed  exclusively  on  gela- 
tine, die  with  the  symptoms  of  starvation.     The  gelatine,  containing  no 
proteine,  cannot  yield  albumen,  fibrine,  or  caseine;  and  it  has  already  been 
stated  that  the  animal  system,  although  it  can  convert  one  form  of  proteine 
into  another,  cannot  form  proteine  from  compounds  which  do  not  contain 
it.     Blood  therefore  cannot  be  made  from  gelatine,  and  the  animal  soon 
dies.     But  when  mixed  with  other  food,  especially  compounds  of  proteine, 
gelatine  may  be  useful,  and  may  serve  directly  to  nourish  the  gelatinous 
tissues.     (Liebig,  Animal  Chemistry,  98,  130.)     This  would  explain  the 
use  of  gelatine  as  a  part  of  the  food  of  convalescents,  whose  debilitated  sys- 
tem cannot  readily  convert  albumen,  &c.  into  gelatine  for  the  nutrition  of 
these  tissues,  and  finds  it  ready-made  in  the  food.     The  experiments  of 
D'Arcet  on  the  gelatine  from  bones  have  proved,  that,  as  part  of  the  diet  in 
hospitals,  gelatine  produces  the  best  effects,  and  materially  abridges  the 

*  How  happens  it  then,  that,  as  it  exists  in  the  hides  or  skins  of  animals,  it  com- 
bines with  tannic  acid  to  form  a  substance  (leather),  precisely  the  same  in  its  che- 
mical composition  as  the  precipitate  formed  by  a  solution  of  gelatine  with  that  acid  ? 

73 


572  ORGANIC  CHEMISTRY. 

period  of  convalescence.     When  it  is  given  alone,  all  animals  soon  refuse 
it  with  disgust,  and  die  if  confined  to  gelatinous  food. 

5794.  "  Chondrine. — This  substance  forms  the  tissue  of  cartilage  as  it 
occurs  in  the  ribs,  trachea,  nose,  &c.  and  of  the  cornea.     It  is  slowly  dis- 
solved by  boiling  with  water,  and  when  dry  resembles  glue.     But  it  differs 
from  gelatine  in  not  being  precipitated  by  tannic  acid,  and  in  giving  pre- 
cipitates with  acetic  acid,  alum,  green  vitriol,  and  acetate  of  lead.     Bones, 
when  in  the  cartilaginous  state,  are  composed  of  it.    According  to  Scherer, 
it   is   composed   of  C48  H40  N6  O30 ;    that   is,    of  proteine  +  4HO  +  O3. 
Chondrine  leaves,  when  burned,  from  4  to  6  per  cent,  of  ashes,  chiefly 
bone-earth. 

5795.  "  Arterial  Membrane. — The  middle  coat  of  the  artery,  which  is 
a  very  elastic  membrane,  leaves,  when   burned,  1.7  per  cent  of  ashes. 
According  to  Scherer,  it  is  composed  of  C48  H38  N8  O16 ;  that  is,  proteine 
+  2HO. 

5796.  "Horny  matter. — This  occurs  in  two  forms,  membranous  and 
compact.     The  former  constitutes  the  epidermis,  and  the  epithelium,  or  the 
lining  membrane  of  the  vessels,  of  the  intestines,  and  of  the  pulmonary  cells. 
The  latter  forms  hair,  horn,  nails,  &c. 

5797.  "  Scherer  has  analyzed  numerous  specimens  of  both  kinds  of 
horny  matter,  and  deduces  from  his  results  the  formula  C48  H39  N7  O17; 
that  is,  proteine  +  NH3  -f  O3. 

5798.  "  Horny  matter,  when  acted  on  by  potash,  yields  proteine  on  the 
addition  of  acetic  acid. 

5799.  "  Feathers  are  closely  allied  to  horny  matters,  but,  according  to 
Scherer,  contain  one  atom  of  oxygen  less ;  the  formula  of  feathers,  deduced 
from  his  analysis,  being  C48  H39  N7  O16. 

5800.  "  Pigmentum  nigrum  oculi. — This  substance,  according  to  Scherer, 
contains  more  carbon  than  any  of  the  preceding ;  but  its  formula  has  not 
been  ascertained. 

5801.  "  It  is  to  be  particularly  observed,  that  the  formula  above  given 
for  the  principal  tissues  of  the  body,  are  only  intended  to  show  the  relation 
they  actually  bear  to  proteine.     It  is  not  meant  that  they  are  formed  in  the 
body  by  the  addition  of  water,  ammonia,  or  oxygen,  to  proteine :  on  the 
contrary,  we  are  as  yet  ignorant  of  the  conditions  under  which  they  are 
produced;  and  in  some  cases,  as,  for  example,  in  gelatine,  several  different 
views  may  be  taken  of  their  formation. 

Brain  and  Nervous  Matter. 

5802.  "  Nervous  matter  is  distinct  from  all  other  animal  tissues,  and  is 
produced  by  the  animal  system  exclusively.     In  composition  it  is  interme- 
diate between  fat  and  the  compounds  of  proteine,  containing  nitrogen,  which 
is  absent  in  fats,  but  in  far  smaller  quantity  than  proteine  does;  and  being, 
on  the  other  hand,  much  richer  in  carbon  than  proteine  or  its  compounds. 
It  appears  likewise  to  contain  phosphorus  as  an  essential  ingredient. 

5803.  "  From  the  recent  researches  of  Fremy,  brain  appears  to  contain 
a  peculiar  acid,  analogous  to  the  fatty  acids,  which  he  calls  cerebric  acid, 
and  which  contains  nitrogen  and  phosphorus;  this  is  mixed  with  an  albu- 
minous substance,  with  an  oily  acid — the  oleophosphoric  acid,  with  choles- 
terine,  and  finally  with  small  quantities  of  oleine  and  margarine,  and  of 
oleic  and  margaric  acids. 

5804.  "  The  two  acids  peculiar  to  the  brain  and  nervous  matter,  occur 


OF  ANIMAL  SUBSTANCES.  573 

sometimes  free,  but  generally  combined  with  soda  or  with  phosphate  of 
lime. 

5805.  "  Cerebric  acid  is  extracted  by  ether  from  the  brain  after  it  has 
been  exposed  to  the  action  of  boiling  alcohol,  which  coagulates  the  albumen. 
The  matter  deposited  on  cooling  by  the  ether  is  a  mixture  of  cerebric  acid, 
generally  combined  with  soda  or  bone-earth,  oleophosphate  of  soda,  and  a 
little  albumen. 

5806.  "  This  mixture  is  acted  on  by  alcohol,  acidulated  with  sulphuric 
acid,  which  precipitates  sulphates  of  lime  and  soda,  and  albumen.     The  fil- 
tered solution  contains  cerebric  and  oleophosphoric  acids;  cold  ether  re- 
moves the  latter,  and  the  former  is  purified  by  solution  in  hot  ether  and 
crystallization. 

5807.  "  When  pure,  it  is  white,  crystalline,  and  pulverizable.     In  hot 
water  it  swells  up  like  starch,  but  does  not  dissolve.     It  contains  phos- 
phorus, but  no  sulphur  if  purified  from  albumen ;  the  phosphorus  amounts 
to  barely  one  per  cent. ;  and  it  contains  2.3  per  cent,  of  nitrogen.     It  has 
the  characters  of  a  fatty  acid,  but  its  acid  properties  are  feebly  marked. 

5808.  "Oleophosphoric  acid. — This  acid  has  not  yet  been  obtained  quite 
pure.     With  the  alkalies  it  forms  soaps,  and  its  compound  with  soda  ap- 
pears to  exist  in  the  brain.     When  it  is  long  boiled  with  water  or  alcohol, 
it  is  resolved  into  oleine  and  phosphoric  acid.     This  change  is  accelerated 
by  acids,  but  it  takes  place  also  spontaneously  at  the  ordinary  temperature, 
only  more  slowly ;  and  the  presence  of  animal  matter  in  a  state  of  decom- 
position seems  to  cause  it  to  be  resolved  into  oleine  and  phosphoric  acid. 
Thus,  when  brain  has  been  allowed  to  undergo  partial  putrefaction,  it  no 
longer  yields  oleophosphoric  acid,  but  oleine  and  phosphoric  acid.     It  con- 
tains two  per  cent,  of  phosphorus.     The  oleine  of  this  acid  is  identical  with 
that  of  human  fat. 

5809.  "  Cholesterine. — This  fat,  as  extracted  from  the  brain,  in  which 
it  occurs  in  considerable  quantity,  has  the  same  composition  and  properties 
as  the  fat  of  biliary  calculi.     (Couerbe;  Fremy.)     Fremy  has  also  suc- 
ceeded in  detecting  in  the  liver,  traces  of  the  characteristic  fat  acids  of  the 
brain. 

5810.  "  The  grey  portions  of  the  brain  appear  to  be  chiefly  albuminous; 
while  the  white  portions  consist  of  an  albuminous  tissue  similar  to  the  grey, 
but  loaded  with  the  fats  above  described. 

5811.  "  The  softening  of  the  brain  in  diseases  of  that  organ  seems  to  be 
the  result  of  putrefaction,  and  is  accompanied  by  the  separation  of  the  oleine 
from  the  phosphoric  acid.     The  oleine  itself  also  is  decomposed,  yielding 
free  oleic  acid. 

5812.  "There  can  be  no  doubt  that  the  brain  and  nervous  matter  (which 
is  quite  similar  to  brain)  are  formed  in   the  body  from  compounds  of  pro- 
teine,  either  by  the  loss  of  some  azotized  compounds,  or  by  the  addition  of 
highly  carbonized  products,  such  as  fat.     But  we  are  ignorant  in  what  part 
of  the  body,  or  by  what  organs,  nervous  matter  is  prepared.     This  point 
requires  minute  investigation.     In  the  mean  time,  according  to  Chevreul, 
the  fatty  matters,  which  occur  in  small  quantity  in  the  blood,  are  similar  to 
those  of  the  brain. 

5813.  "Bones. — The  bones  of  animals  are  composed  of  bone-earth  and 
gelatinous  tissue.     By  the  action  of  hydrochloric  acid,  the  earthy  matter  is 
dissolved,  and  the  animal  tissue  is  left.     It  is  soft,  retains  the  form  of  the 
bone,  and,  when  dried,  becomes  brittle  and  semitransparent.     When  boiled 


574  ORGANIC  CHEMISTRY. 

with  water,  it  yields  a  solution  of  gelatine,  fatty  matter  remaining  undis- 
solved. 

5814.  "  Tljeaearthy  matter  is  formed  of  a  peculiar  phosphate  of  lime, 
8CaO  +  3P3  0*=  HO,  2CaO,  P2  O5  -f  2(3CaO,  P2  O);  that  is,  a  com- 
pound  of  two  forms  of  tribasic  phosphate.     It  forms  rather  more  than  half 
the  weight  of  the  bone,  and  contains  a  variable  proportion  of  carbonate  of 
lime.     Fluoride  of  calcium  is  sometimes,  but  not  always,  present  in  recent 
bones;  in  fossil  bones,  and  in  human  bones  from  Herculaneum,  it  is  always 
found. 

5815.  "Teeth  contain  the  same  ingredients  as  bones,  but  the  proportion 
of  earthy  matter  is  greater,  amounting  to  nearly  seventy  per  cent.     The 
enamel  of  the  teeth  contains  no  animal  matter,  and  fluoride  of  calcium  is 
found  in  it. 

5816.  "In  rickets,  the  proportion  of  earthy  matter  is  much  diminished. 
Callus  and  exostosis  are  said  by  Valentin  to  contain  more  carbonate  of  lime 
than  sound  bone,  and  carious  bone  to  contain  less. 

5817.  "When  bones  are  heated  in  the  open  fire,  they  leave  an  earthy 
skeleton,  which  is  quite  white,  and  has  the  form  of  the  bone.     If  bones  are 
heated  in  close  vessels,  they  give  off  carbonate  of  ammonia  and  tarry  pro- 
ducts, and  leave  a  black  mass,  which  consists  of  bone-earth,  with  about  ten 
per  cent,  of  finely  divided  charcoal.     It  is  called  bone  or  ivory-black,  and 
is  much  used  to  decolorize  organic  solutions. 

Animal  Secretions  and  Excretions. 

5818.  "Milk. — This  important  secretion,  destined  for  the  support  of  the 
young  of  the  mammalia,  is  characterized  by  the  caseine  it  contains.     But 
it  also  contains  certain  oily  or  fatty  matters  which  constitute  butter,  and 
which,  besides  fats  analogous  to  the  ordinary  animal  fats,  contain  certain 
volatile  acids  (5052,  5056),  to  which  the  smell  and  peculiar  taste  of  butter 
are  owing.     Milk  further  contains  sugar  of  milk,  or  lactine  (4070) ;  and, 
when  the  caseine  has  been  coagulated  by  an  acid,  the  whey,  besides  lactine 
and  salts,  contains  an  albuminous  matter,  which  is  coagulated  by  heat. 

5819.  "  The  composition  of  milk  is  such,  that  it  is  capable  of  supporting 
animal  life  without  any  other  food.     Its  caseine  and  albumen  serve  for  the 
formation  of  blood,  and  for  the  nutrition  of  the  animal  tissues,  while  its  su- 
gar and  fat  support  respiration ;  and  it  furnishes,  besides,  all  the  salts  which 
the  body  requires. 

5820.  "  The  following  table  exhibits  the  composition  of  the  milk  of  wo- 
man, of  the  ass,  and  of  the  cow.     (Henry  and  Chevallier.) 

Milk  of 

Woman.  Ass.  Cow. 

Cheese  or  caseine               -            -            1.52  1.82  4.48 

Butter          ....            3.55  0.11  3.13 

Sugar  of  milk         -                                     6.50  6.08  4.77 

Salts  and  mucus     -            -            -            0.45  0.34  0.60 

Water         ....          87.98  91.65  87.02 


100.00    100.00    100.00 


5821.  "  When  the  food  is  highly  farinaceous,  the  proportion  of  butter  is 
increased ;  but  when  the  food  contains  much  of  the  compounds  of  proteine, 
there  is  less  butter  and  more  caseine  present.  The  more  active  exercise  is 
taken,  the  smaller  also  is  the  proportion  of  butter. 


OP  ANIMAL  SUBSTANCES. 


575 


5822.  "  Milk,  after  it  has  become  sour,  undergoes  the  vinous  fermenta- 
tion (5215). 

5823.  "  Saliva. — This  fluid,  secreted  by  the  salivary  glands,  is  com- 
posed of  water,  with  about  one  per  cent,  of  solid  matter,  partly  saline.     It 
often  contains  a  trace  of  sulphocyanide  of  potassium,  or  at  least  of  a  salt 
which  strikes  a  red  colour  with  persalts  of  iron ;  but  this  might  be  done  by 
an  acetate.     The  animal  matter  of  saliva  has  been  described  under  the 
name  of  Salivary  matter.     It  is  soluble  in  water,  and  not  coagulated  by 
heat. 

5824.  "  Saliva  possesses,  in  an  eminent  degree,  the  property  of  frothing 
with  air,  like  a  solution  of  soap;  and  Liebig  (Animal  Chemistry,  p.  113) 
conceives  that  its  use  is  to  introduce  in  this  manner,  during  mastication,  a 
certain  quantity  of  air  into  the  stomach,  the  oxygen  of  which  is  employed 
in  digestion.* 

*  As  I  find  that  Berzelius,  Graham,  and  Kane,  give  more  importance  to  pepsine 
than  is  accorded  by  Liebig  and  Gregory,  I  deem  it  expedient  to  subjoin  the  follow- 
:ount  of  it,  prepared  by  me  recently,  from  Berzelius'  Report,  1840, 


ing  abridged  account  of  it,  preparei 
322,  and  Graham's  Elements,  1030. 


Pepsine. 

The  name  of  pepsine  has  been  given  to  a  peculiar  matter  constituting  the  active 
principle  of  the  gastric  fluid,  the  discovery  of  which  is  due  to  Mr.  Wasmann.  Pep- 
sine may  be  obtained  by  infusing  the  mucous  membrane  of  the  stomach  in  acidu- 
lated water.  The  solution  thus  procured,  has  the  property  of  dissolving  the  coagu- 
lated white  of  egg  completely  in  half  an  hour. 

When  the  membrane,  without  being  cut  into  pieces,  but  well  washed,  is  digested 
in  a  large  quantity  of  water,  at  a  temperature  between  86°  and  98°,  a  variety  of  sub- 
stances are  extracted  as  well  as  pepsine ;  but  if  afterwards  cold  water  be  substituted 
for  the  warm,  scarcely  any  matter  besides  pepsine  is  taken  up.  The  extraction  may 
endure  with  successive  portions  of  water,  until  symptoms  of  putrefaction  ensue. 
The  solution  thus  obtained,  with  the  addition  of  a  little  chlorohydric  acid,  has  the 
property  of  dissolving  coagulated  albumen  speedily.  Pepsine,  extracted  by  these 
means,  contains  a  little  albumen,  which  may  be  precipitated  by  ferrocyanide  of  po- 
tassium, or  by  heating  the  solution,  if  not  too  dilute,  to  a  temperature  between  170° 
and  212°  without  ebullition.  By  these  means  the  coagulated  albumen  is  precipitated 
in  flocks,  with  a  little  modified  caseine. 

Pepsine  may  be  precipitated  from  its  solutions  by  the  protosulphate  of  iron,  sul- 
phate of  copper,  acetate  of  lead,  or  protochloride  of  tin.  From  the  precipitates  thus 
made,  it  may  be  separated  by  exposure,  while  suspended  in  water,  to  sulphydric 
acid. 

In  precipitating,  pepsine  retains  a  sufficient  portion  of  the  acid  of  the  saline  pre- 
cipitant to  have  a  decided  reaction  with  litmus,  and  is  highly  endowed  with  its  ap- 
propriate solvent  powers. 

Acetate  of  pepsine  may  be  procured  by  decomposing,  by  sulphydric  acid,  the  pre- 
cipitate made  as  above  suggested,  by  acetate  of  lead,  evaporating  the  residual  solu- 
tion to  the  consistence  of  syrup,  and  subjecting  it  to  alcohol.  The  acetate  separates 
in  white  flocks,  which,  by  desiccation,  acquire  the  appearance  of  a  gum,  and  are 
readily  soluble  in  water.  Of  pepsine  in  this  form,  one  part  in  60,000  parts  of  water, 
with  a  minute  addition  of  chlorohydric  acid,  dissolves  indurated  albumen  within 
about  six  or  eight  hours. 

A  similar  efficacy  is  ascribed  to  the  chlorohydrate  of  pepsine,  which  may  be  ob- 
tained by  precipitating  the  solution  by  bichloride  of  mercury,  and  subjecting  the  pre- 
cipitate to  the  process  above  described  in  case  of  the  acetate. 

Mr.  Wasmann  has  remarked,  that  the  pepsine  obtained  from  the  pig  is  devoid  of 
the  power  to  coagulate  milk,  although  that  of  the  calf  is  highly  endowed  with  this 
power. 

Agreeably  to  some  comparative  trials  of  the  solvent  powers  of  dilute  chlorohydric 
acid,  without  pepsine,  and  one  other  portion  of  the  same  acid  containing  this  princi- 
ple, it  appeared  that  the  one  was  endowed  with  all  the  solvent  powers  of  the  gastric 
fluid  in  a  high  degree,  at  ordinary  temperatures,  while  the  other,  under  like  circum- 
stances, displayed  them  only  to  an  insignificant  extent;  but  when  the  acid,  without 
pepsine,  was  aided  by  boiling  heat,  its  solvent  powers  were  equal  to  that  of  the  solu- 
tion of  pepsine. 


576  ORGANIC  CHEMISTRY. 

5825.  "  Gastric  Juice. — This  remarkable  fluid  seems  to  contain  hardly 
any  principle  capable  of  accounting  for  its  solvent  power.     In  the  empty 
stomach  it  is  neutral,  but  during  digestion  it  becomes  acid,  from  the  sepa- 
ration of  free  muriatic  acid.     According  to  Wasmann  and  other  chemists, 
it  contains  a  peculiar  principle,  Pepsine,  which  has  the  property  of  dissolv- 
ing food,  and  which  is  obtained  by  the  action  of  water  on  the  well-washed 
lining  membrane  of  the  stomach  of  the  pig.    According  to  Liebig,  however, 
pepsine,  as  a  distinct  compound,  does  not  exist.     The  solution  of  the  lining 
membrane,  slightly  acidulated  with  chlorohydric  acid,  certainly  dissolves 
albumen  and  fibrine,  if  kept  in  contact  with  them  out  of  the  body  at  the 
ordinary  temperature.     But  none  of  these  effects  take  place,  unless  the 
membrane  has  been  previously  exposed  to  the  air,  and  is  in  a  state  of  de- 
composition.    Hence  Liebig  ascribes  (Animal  Chemistry,   109  seq.)  the 
solvent  power  of  the  gastric  juice  to  the  gradual  decomposition  of  a  matter 
dissolved  from  the  membrane,  aided  by  the  oxygen  introduced  in  the  saliva. 
Albumen,  &c.  when  thus  in  contact  with  decomposing  or  fermenting  mat- 
ter, are  rendered  soluble  by  a  new  arrangement  of  their  particles.     The 
accumulation  of  free  chlorohydric  acid,  derived,  no  doubt,  from  common 
salt,  at  last  puts  a  stop  to  further  change.     The  whole  food  is  now  brought 
into  the  form  of  chyme,  an  opaque  homogeneous  fluid,  which  afterwards 
passes,  first  into  chyle,  and  finally  into  perfect  blood.     In  the  chyle,  the 
formation  of  fibrine  has  already  taken  place ;  for,  when  drawn,  it  coagu- 
lates spontaneously,  like  blood.* 

5826.  "  Pancreatic  Juice.— The  fluid  secreted  by  the  pancreas  is  pour- 
ed into  the  duodenum,  and  mixes  with  the  chyme  as  the  latter  leaves  the 
stomach.     It  contains  albumen,  and,  according  to  some,  caseine,  and  is 
acid.     Its  nature,  however,  is  little  understood,  and  its  uses  at  present  are 
unknown. 

Bile  and  Biliary  Calculi. 

5827.  "  The  bile  is  a  yellowish  green  viscid  liquid,  secreted  by  the  liver. 
It  has  a  faint  disagreeable  smell ;  and  its  taste  is  at  first  sweet,  afterwards 
bitter  and  nauseous.     Ox  bile  has  been  chiefly  examined,  but  that  of  man 
and  other  animals  is  very  similar.     The  researches  of  Tiedemann  and 
Gmelin,  of  Berzelius  and  Demarcay,  have  shown  that  bile  may  be  made 
to  yield  a  vast  number  of  different  compounds,  most  of  which  are  products 
of  decomposition. 

5828.  "  The  bile,  according  to  Demar9ay,  contains  soda  in  combination 
with  a  peculiar  acid,  choleic  acid.     When  bile  is  boiled  with  an  excess  of 
chlorohydric  acid,  it  yields  ammonia,  taurine,  and  choloidic  acid;  and, 
when   boiled  with  caustic  potash,  it  yields  carbonic  acid,  ammonia,  and 
cholic  acid. 

5829.  "  Choleic  Acid. — When  bile  is  acted  on  by  alcohol,  certain  im- 
purities are  left  undissolved.     The  purified  bile  gives  with  acetate  of  lead  a 

*  Chyle  resembles  blood  in  resolving  itself  into  a  coagulum,  and  a  liquid  like  se- 
rum, which,  according  to  Dr.  Prout,  consists  partly  of  albumen,  but  principally  of 
incipient  albumen.  The  coagulum,  according  to  Vauquelin,  is  imperfect  fibrin ;  but 
Brande  considers  it  as  more  allied  to  caseous  matter. 

The  opinions  of  Prout  and  Vauquelin  derive  support  from  the  consideration  that, 
as  chyle  is  destined  to  become  blood,  it  may  be  reasonably  expected  to  contain  the 
principal  constituents  of  that  liquid,  in  a  state  advancing  towards  maturity.  These 
inferences  respecting  chyle,  made  in  the  former  edition  of  this  Compendium,  appear 
to  be  sanctioned  by  those  of  Liebig  expressed  in  the  text. 


OP  ANIMAL  SUBSTANCES.  577 

precipitate  of  choleate  of  lead,  which,  when  acted  on  by  sulphuretted  hy- 
drogen, yields  choleic  acid. 

5830.  "  It  forms  a  yellow  spongy  mass,  soluble  in  water  and  alcohol, 
which  has  an  acid  reaction  and  a  bitter  taste,  and  is  decomposed  by  heat. 
It  combines  with  soda,  forming  a  compound  which  Dema^ay  considers  as 
a  soap,  the  solution  of  which  in  water  has  the  physical  characters  of  bile. 
But  although  this  be  the  case,  and  although  the  composition  of  the  choleic 
acid  appears  to  be  the  same  as  that  of  the  organic  part  of  bile,  yet  we  can- 
not consider  the  bile  as  choleate  of  soda ;  for  the  latter  is  decomposed  by 
acetic  acid,  which  has  no  action  on  bile. 

.5831.  "  According  to  the  analyses  of  Demarcay  and  Dumas,  as  calcu- 
lated by  Liebig,  the  formula  of  choleic  acid  is  C76H66NaO3,  and  this  for- 
mula may  represent  also  the  organic  part  of  the  bile. 

5832.  "  When  choleic  acid  is  boiled  with  chlorohydric  acid,  it  yields 
ammonia,  taurine,  and  choleidic  acid.     The  latter,  being  insoluble,  is  de- 
posited, and  the  taurine  is  extracted  from  the  mother  liquor  by  concen- 
trating and  adding  a  large  quantity  of  alcohol,  when  the  taurine  slowly 
crystallizes. 

5833.  "  Choloidic  Acid. — This  acid  is  solid,  fusible,  of  a  yellow  colour 
and  bitter  taste,  insoluble  in  water,  soluble  in  alcohol.     It  combines  with 
bases,  neutralizing  them,  and  forming  salts  which  are  soluble  in  alcohol. 
It  contains  no  nitrogen,  and  its  formula  is  C73H56O13. 

5834.  "  Taurine. — This    substance    forms    white   crystalline    needles, 
which  are  soluble  in  water,  and  sparingly  soluble  in  alcohol.     Its  formula 
is  C4  H7  NO10. 

5835.  "  The  production  of  these  substances  is  easily  explained. 

If  from  choleic  acid         .  .  .  C™  H™  N2  022, 

We  subtract  1  atom  taurine     C4  H?  NO10  )        ,-,,   Uin  «,  ^.n 
And  1  atom  ammonia       .  R3  N        ]  =  *°> 

There  remains  1  atom  choloidic  acid      .        =  C™  K™  O'2 

5836.  "  Cholic  acid. — This  acid  is  formed,  along  with  carbonic  acid 
and  ammonia,  when  bile  or  choleic  acid  is  boiled  with  an  excess  of  caustic 
potash.     It  is  precipitated  by  acetic  acid,  and  purified  by  alcohol  from  un- 
altered choleic  acid. 

5837.  "When  pure,  it  forms  fine  needles,  which  are  permanent  in  the 
air;  or  large  tetraedrons,  which  become  opaque  on  exposure.     It  is  inso- 
luble in  water,  soluble  in  alcohol  and  ether.     It  forms  neutral  salts  with 
bases.     Its  formula  is  C74  H60  O18,  and  its  formation  is  easily  explained. 

If  from  choleic  acid  C™  H<*  N2  O^, 

We  subtract 2  atoms  carbonic  acid   C2  O4  )        ^  Tjfi 
And  2  atoms  ammonia     .  .       N2  Re  <  —  ^    '    ' 


There  remains  1  atom  cholic  acid  .        =  C74  H60  O18 

5838.  "  Berzelius  states  that  the  bile  is  far  from  being  so  simple  in  its 
constitution  as  Dema^ay  supposes;  and  by  a  series  of  ingenious  processes 
has  obtained  from  the  bile  a  number  of  different  substances,  which  he  has 
named  Biline,  Biliverdine,  Dyslysine,  Fellinic  Acid,  and  Cholinic  Acid, 
besides  taurine  and  cholic  acid,  as  already  described.  Biline  is  essentially 
the  same  as  Demarcay's  choleic  acid ;  and  it  is  probable  that  most  of  the 
others  are  products  of  decomposition.  But  even  supposing  choleic  acid  to 
be  composed  of  two  or  more  different  compounds,  not  isolated  by  Demar- 


578  ORGANIC  CHEMISTRY. 

9&y,  yet>  as  Liebig  has  well  remarked,  (Animal  Chemistry,  315)  we  must 
not  overlook  the  fact,  that  it  is  constant  in  its  composition,  and  that  from 
this  composition  we  can  deduce  the  principal  products  of  the  action  of  acids 
and  alkalies  on  bile.  It  is  choleic  acid  or  bile  as  a  whole,  whether  it  be  one 
compound  or  a  mixture  of  several,  to  which  we  have  to  look  for  the  expla- 
nation of  the  changes  by  which  bile  may  be  formed  or  decomposed.  The 
researches  of  Berzelius  have  rendered  it  probable  that  choleic  acid  is  not  a 
single  compound ;  but  this  does  not  affect  its  ultimate  composition,  nor  its 
relation  to  decomposing  agents.  It  is  also  clear  that  bile  is  very  prone  to 
change  in  almost  all  circumstances,  and  yields  a  great  variety  of  products, 
most  of  which  have  little  physiological  interest.  For  these  reasons  we  shall 
merely  refer  the  reader  to  the  elaborate  paper  of  Berzelius  in  the  foreign 
journals.  The  results  of  Demargay  we  have  given  more  in  detail ;  because, 
as  calculated  and  interpreted  by  Liebig,  they  admit  of  direct  application  to 
physiology. 

5839.  "  When  dried  bile  is  acted  on  by  alcohol,  the  pure  bile  or  choleate 
of  soda  is  dissolved,  and  the  residue  is  found  to  contain  mucus,  salts,  and 
fatty  matter.     The  latter  consist  of  cholesterine  and  ordinary  fat,  and  pos- 
sibly contain  a  portion  of  the  peculiar  fats  of  brain.   The  dissolved  portion, 
besides  true  bile,  contains  a  small  portion  of  soaps  of  margaric  and  oleic 
acids  with  soda. 

5840.  "  The  sugar  of  bile  or  picromel  of  Gmelin,  so  called  from  its  sweet 
and  bitter  taste,  appears  to  be  choleic  acid  or  biline,  altered  by  the  processes 
to  which  it  has  been  subjected. 

5841.  "  Biliary  Calculi. — The  concretions  which  form  in  the  gall-blad- 
der, and  are  often  the  cause  of  much  suffering,  are  almost  always  composed 
of  cholesterine,  with  more  or  less  colouring  matter.     Hot  alcohol  dissolves 
the  cholesterine,  and  deposits  it  in  shining  scales  on  cooling.    These  calculi 
have  often  a  form  nearly  cubical,  and  a  pearly  lustre. 

5842.  "  Lithofellic  Acid. — This  acid  has  recently  been  discovered  by 
Goebel  in  a  biliary  concretion,  and  appears  to  be  the  chief  constituent  of 
the  concretions  called  bezoar  stones,  which  occur  in  herbivorous  animals. 
According  to  Ettling  and  Will,  its  formula  is  C40H36O8.     It  is  soluble  in 
'hot  alcohol,  and  forms  a  crystalline  powder  on  cooling.     It  is  insoluble  in 
water,  and  forms  with  alkalies  soluble  soaps,  with  oxides  of  lead  and  silver 
insoluble  compounds.     It  is  decomposed  by  heat,  and  when  acted  on  by 
nitric  acid  yields  a  new  acid. 

5843.  "  According  to  Liebig,  who  deduced  the  above  formula  from  the 
analysis  of  Ettling  and  Will,  lithofellic  acid  may  be  formed,  along  with 
hippuric  acid,  by  the  oxidation  of  choleic  acid. 

•  j  r*i*  rr«R  TWO  r*w  }  C  2  eq.  hippuric  acid,  CSG  H'6  N2  O'° 
1  eq  choleic  acid,  C™  H<*  N*  O  £  =  S  l  JJ  lit^fellic  acij  C40  H36  O  8 
and  10  eq.  oxygen,  O'o£  ^4^.  water,  H"  OH 

C?6  R66  N2  Q32  O  H™  N*  O32 


5844.  "Excrements. — The  excrements  of  man  contain  about  one-fourth 
of  their  weight  of  solid  matter.  The  ashes  of  dry  faeces  amount  to  13.58 
to  15.00  per  cent.,  and  are  composed  of  phosphates  and  other  salts.  The 
excrements  also  contain  nitrogen,  and  yield  ammonia  when  they  putrefy. 
The  value  of  night-soil  as  manure  depends  on  the  salts  and  ammonia  of  the 
faBces,  and  also  in  a  great  measure  on  the  ammoniacal  and  other  salts  of 


OP  ANIMAL  SUBSTANCES.  579 

the  urine.  The  colour  of  faeces  is  generally  said  to  be  owing  to  bile ;  but 
Liebig  states  that  there  is  only  a  mere  trace  of  bile,  if  any,  to  be  found  in 
the  freces  either  of  man  or  animals.  The  yellow  matter  of  faeces  is  insolu- 
ble in  alcohol,  with  the  exception  of  a  small  proportion,  and  even  that  has 
not  the  characters  of  bile. 

5845.  '•'•Lymph. — The  lymph  of  cellular  membrane  is  water,  with  a 
small  trace  of  albumen  and  of  common  salt.     The  lymph  secreted  by  the 
serous  membranes  is  much  more  highly  charged,  containing  seven  or  eight 
per  cent,  of  albumen  and  salts.     It  coagulates  when  heated,  or  by  the  ac- 
tion of  nitric  acid.     The  liquor  amnii  and  the  fluid  of  hydatids  is  similar; 
but  the  fluid  of  dropsy  is  said  to  contain  urea,  and  to  have  cholesterine  sus- 
pended in  it. 

5846.  "Mucus. — This  is  the  secretion  of  the  mucus  membranes.     When 
dried,  it  leaves  six  or  seven  per  cent,  of  yellowish  solid  matter,  of  which 
about  five  parts  are  mucus,  the  remainder  albumen  and  salts.     Mucus  does 
not  dissolve  in  water,  but  swells  like  tragacanth  into  a  viscid  mass.     It  dis- 
solves in  caustic  potash. 

5847.  "  Pus  is  the  matter  secreted  by  ulcerated  surfaces.    When  healthy, 
it  is  a  thick  yellowish  liquid,  formed  of  opaque  globules  floating  in  a  clear 
fluid.     When  mixed  with  water,  the  globules  fall,  forming  a  yellow  insolu- 
ble sediment.     Pus  contains  about  14  per  cent,  of  solid  matter,  and  is  co- 
agulated by  heat  and  by  acids.     It  contains  albuminous  matter,  fatty  mat- 
ter, and  salts. 

5848.  "  The  matter  of  the  globules  of  pus  is  similar  to  that  of  the  glo- 
bules of  blood,  or  globuline.     Pus  is  distinguished  from  mucus  by  the  mi- 
croscope, or  by  the  action  of  caustic  potash,  with  which  pus  becomes  thick 
and  ropy,  while  mucus  forms  a  thin  solution. 

Urine  and  Urinary  Calculi. 

5849.  "Urine. — This  important  excretion  is  separated  from  the  arterial 
blood  in  the  kidneys.     It  has  a  pale  yellow  colour,  and  a  peculiar  smell. 
Its  density  varies  from  1.012  to  1.030.     It  has  an  acid  reaction,  or  is  neu- 
tral, but  never  alkaline  in  a  state  of  health. 

5850.  "  On  standing,  it  deposits  a  slimy  mucus-like  substance,  secreted 
from  the  lining  surface  of  the  bladder.     This  mucus  acts  as  a  ferment,  and 
causes  the  urine,  after  a  time,  to  undergo  decomposition ;  for,  when  it  is 
separated  by  the  filter,  the  urine  may  be  kept  unchanged  for  a  much  longer 
time. 

5851.  "  When  spontaneous  decomposition  has  taken  place,  the  urine  is 
alkaline  from  the  presence  of  carbonate  of  ammonia,  derived  from  the  urea. 
Urine  contains  about  seven  or  eight  per  cent,  of  solid  matter,  the  remainder 
being  water. 

5852.  "  The  characteristic  organic  principles  of  urine  are  urea  and  uric 
acid  (5359,  5361).     The  urea*  has  been  recently  declared  by  Cap  and 

*  "Anomalous  Cyanate  of  Ammonia;  Urea. — Discovered  by  Fourcroy  and  Vau- 
quelin  in  urine,  by  Wohler  as  the  first  organic  compound  artificially  produced.  It 
is  a  constituent  of  uric  acid,  and  is  contained  in  the  urine  in  combination  with  lactic 
acid  (Henry).  Urea  is  also  a  product  of  the  reaction  of  cyanogen  on  water  when  a 
solution  of  that  gas  is  allowed  to  undergo  spontaneous  decomposition  (Pelouze  and 
Richardson). 

"  Prep. — By  mixing  fresh  urine  evaporated  to  the  consistence  of  a  syrup  at  a  gen- 
tle heat,  which  should  never  reach  that  of  ebullition,  when  still  warm,  with  its  own 
volume  of  colourless  nitric  acid  of  sp.  gr.  =  1.42.  If  the  evaporation  has  been  car. 
74 


580  ORGANIC  CHEMISTRY. 

Henry  to  be  combined  with  lactic  acid ;  but,  in  repeating  their  experiments, 
the  editor  has  always  obtained  pure  urea  instead  of  the  lactate.  It  would 
appear,  therefore,  that  in  some  individuals  it  occurs  uncombined,  in  others 

ried  sufficiently  far,  the  whole  will  form  a  thick  crystalline  mass;  to  insure  this,  a 
small  portion  of  the  urine  should  be  tried  from  time  to  time.  The  crystalline  mass 
consists  of  a  compound  of  nitric  acid  and  urea,  which  is  sparingly  soluble  in  nitric 
acid.  By  the  action  of  the  nitric  acid  on  the  warm  solution,  heat  is  developed,  and 
effervescence  ensues.  This  is  chiefly  owing  to  the  destruction  of  the  colouring  mat- 
ter, and  if  no  external  heat  is  applied,  the  urea  not  only  is  not  decomposed,  but 
forms,  from  the  first,  nearly  white  crystals  of  nitrate.  When  cold  is  employed,  ac- 
cording to  the  method  formerly  recommended,  the  crystals  are  very  brown,  and  are 
purified  with  difficulty.  It  is  advisable  to  separate  from  the  inspissated  urine  as 
much  as  possible  of  the  chlorides  it  contains,  by  crystallization,  before  adding  the 
nitric  acid  (Cap  and  Henry). 

"  A  solution  of  the  colourless  crystals  of  the  nitrate  of  urea  is  treated  with  car- 
bonate of  baryta  until  it  is  rendered  perfectly  neutral ;  on  evaporating,  crystals  of 
nitrate  of  baryta,  and  then  of  urea,  will  be  obtained.  The  crystals  of  the  latter,  by 
being  redissolved  in  a  little  cold  water,  are  freed  from  the  last  portions  of  the  nitrate 
of  baryta;  the  solution  in  alcohol  gives  crystals  of  pure  urea  (Wohler).  Gregory 
states  that  coloured  crystals  of  urea  are  best  decolorized  by  a  little  permanganate  of 
potash,  which  destroys  the  colouring  matter,  but  has  no  action  on  urea.  Any  ex- 
cess of  the  salt  is  removed  by  alcohol,  which  converts  it  into  peroxide  of  manga- 


"  Instead  of  using  nitric  acid,  the  concentrated  urine  may  be  added  to  a  boiling 
saturated  solution  of  oxalic  acid,  when  the  sparingly  soluble  oxalate  of  urea  falls, 
which,  after  being  deprived  of  its  colour  by  charcoal,  may  be  decomposed  into  the 
insoluble  oxalate  of  lime  and  pure  urea,  by  being  digested  with  pounded  chalk  (Ber- 
zelius).  It  can  also  be  prepared  by  the  decomposition  of  the  cyanate  of  oxide  of 
silver  by  sal  ammoniac,  or  of  the  cyanate  of  oxide  of  lead  by  pure  or  carbonate  of 
ammonia.* 

"  Prop. — Crystallizes  in  colourless,  transparent,  four-sided,  somewhat  flattened 
prisms,  of  the  sp.  gr.  1.35,  is  soluble  in  its  own  weight  of  cold,  and  in  every  propor- 
tion in  hot  water,  in  4.5  parts  of  cold,  and  in  2  parts  of  boiling  alcohol :  the  aqueous 
solution  has  a  cooling  bitter  taste  like  nitre ;  when  pure,  it  is  perfectly  permanent 
in  the  air,  is  not  deliquescent,  fuses  at  250°  into  a  colourless  liquid,  is  decomposed 
by  a  higher  temperature  into  ammonia,  cyanate  of  ammonia,  and  dry  solid  cyanuric 
acid.  Alkalies  do  not  cause  the  separation  of  ammonia  in  the  cold.  Unites  with 
several  acids  without  decomposition  to  crystallizable  saline  compounds:  by  evapo- 
rating its  solution  with  nitrate  of  silver  or  acetate  of  lead  it  is  decomposed;  the  pro- 
ducts being,  with  the  first,  nitrate  of  ammonia  and  crystalline  cyanate  of  silver;  with 
the  second,  acetate  of  ammonia  and  carbonate  of  lead.  With  hyponitrous  acid  it  is 
instantly  decomposed  into  nitrogen  and  carbonic  acid  gases,  which  are  evolved  in 
equal  volumes;  with  chlorine  it  forms  hydrochloric  acid,  nitrogen,  and  carbonic 
acid.  When  fused  with  the  hydrated  alkalies,  or  heated  in  concentrated  sulphuric 
acid,  it  is  decomposed  together  with  the  constituents  of  three  eq.  of  water  into  car- 
bonic acid  and  ammonia.  Urea  contains  the  elements  of  cyanate  of  ammonia  (NH4O 
-j-  C2NO);  it  may  also  be  considered,  according  to  Dumas,  as  a  second  compound  of 
carbonic  oxide  and  amide,  in  which  the  quantity  of  the  latter  is  double  that  in  ox- 
amide  C^  02  -f  2NH2. 

"  Nitrate  of  Urea. — This  compound,  when  recently  precipitated  from  urine,  ap- 
pears in  the  form  of  fine  crystalline  plates  of  a  brown  colour  and  mother-of-pearl 
lustre;  the  purer  they  are,  the  more  they  lose  this  appearance:  a  solution  of  pure 
urea  treated  with  nitric  acid  gives  a  granular  white  crystalline  precipitate,  which  is 
soluble  in  eight  parts  of  cold,  but  more  freely  in  hot  water,  from  which  it  crystallizes 
in  broad,  scarcely  translucent  plates ;  is  sparingly  soluble  in  nitric  acid,  with  which 
it  may  be  boiled  without  decomposition.  Is  composed  of  one  eq.  of  nitric  acid,  one 
of  urea,  and  one  of  water  (Regnault)." 

*  I  am  surprised  the  following  process  is  not  mentioned  : — Impure  cyanate  of  pot- 
ash is  prepared  by  roasting  the  cyanoferrite  of  potassium.  Aqueous  solutions  of  the 
cyanate  thus  obtained,  and  of  sulphate  of  ammonia,  being  mingled,  the  aggregate 
is  subjected  to  boiling  alcohol,  which  takes  up  the  urea  only.  On  cooling,  the  urea 
crystallizes,  and  may  be  rendered  purer  by  recrystallization  from  the  same  men- 
struum. Kane,  1164. 


OF  ANIMAL  SUBSTANCES.  581 

as  lactate.  It  is  not  known  precisely  in  what  state  of  combination  the  uric 
acid  occurs;  but,  when  it  is  not  deposited  spontaneously,  it  appears  on  the 
addition  of  an  acid,  and  the  spontaneous  deposition  of  it  is  probably  owing 
to  the  presence  of  free  acid  in  unusual  quantity. 

5853.  "  The  proportion  of  urea  has  been  found  by  Lecanu  to  be  tolera- 
bly uniform  in  the  same  individual,  but  to  vary  much  in  different  persons. 
It  is  larger  in  adult  men  than  in  women,  and  least  of  all  in  old  people  and 
very  young  children.     The  proportion  of  uric  acid  varies  in  a  similar  way. 
The  following  analysis  of  urine,  by  Berzelius,  will  give  a  view  of  the  usual 
composition  of  human  urine : — 

Water            .......  933.00 

Urea              ...----  30.10 

Uric  acid       .......  1.00 

Lactic  acid,  lactate  of  ammonia,  and  animal  matter  ad- 
hering to  them                           -                        -            -  17.14 
Mucus  of  the  bladder           .....  0.32 

Sulphate  of  potash                            -            -            -  3.71 

Sulphate  of  soda       ..----  3.16 

Phosphate  of  soda     -                                      -                         -  2.94 

Phosphate  of  ammonia          -            -            -            -            -  1.65 

Chloride  of  sodium                .....  4.45 

Hydrochlorate  of  ammonia               -                        -  1.50 

Earthy  matters,  with  a  trace  of  fluoride  of  calcium            -  1.00 

Siliceous  earth          ....                       -  0.03 

1000.00 

5854.  "  Scharling  has   recently  examined  the  brown  organic  matter 
which  gives  the  colour  to  inspissated  urine,  and  seems  also  to  be  the  source 
of  its  peculiar  odour.     He  obtained  a  brown,  fusible,  resinous  mass,  having 
a  strong  odour  of  castoreum  when  dry,  and  a  urinous  smell  when  boiled 
with  water.     He  calls  it  oxide  of  omichmyle,  (from  0ft/£p«,  urine,)  and 
supposes  it  to  contain  a  radical,  omichmyle,  the  composition  of  which  is  still 
unknown. 

5855.  "  When  urine  is  distilled  with  an  excess  of  nitric  acid,  there  are 
formed  several  products,  among  which  Scharling  states  that  he  has  observed 
benzoic  acid,  and  an  acid  containing  chlorine  derived  from  the  salts  of  the 
urine.     This  acid  appears  also  to  be  formed  when  oxide  of  omichmyle  is 
distilled  with  nitromuriatic  acid.     From  his  analysis,  Scharling  deduces  the 
formula  C14  H4  Cl  O3  -f  HO,  which  represents  benzoic  acid,  in  which  one 
eq.  of  hydrogen  is  replaced  by  one  eq.  of  chlorine.     It  is  also  isomeric  with 
chloride  of  salicule  or  chlorosaliculic  acid  (5336). 

5856.  "Along  with  this  acid  there  is  formed  a  volatile  greenish-yellow 
oil,  which  Scharling  found  to  contain  twice  as  much  chlorine,  and  the  ele- 
ments of  nitric  acid.    This  compound  he  calls  nitro-chloromichmyle.    When 
heated  with  acids,  it  is  decomposed,  and  yields  another  oily  matter,  chloro 
michmyle.     All  these  observations  require  confirmation. 

5857.  "The  urine  of  herbivora  is  alkaline,  and,  when  the  animals  are 
stall-fed,  contains,  besides  urea,  hippuric  acid ;  but  when  they  live  in  the 
open  air,  or  are  forced  to  labour,  benzoic  acid  alone  is  found. 

5858.  "  The  urine  of  the  carnivora  is  acid,  and  contains  phosphates  and 
sulphates  of  ammonia  and  soda,  as  well  as  uric  acid  and  urea. 

5859.  "The  urine  of  serpents  and  of  birds  is  of  a  soft  semisolid  consist- 
ence, and  dries  into  a  mass  like  chalk.     It  is  almost  pure  urate  of  ammo- 
nia, but  contains  a  small  quantity  of  phosphates. 


582  ORGANIC  CHEMISTRY. 

5860.  "Urinary  Calculi. — The  most  abundant  calculi  are  those  of  uric 
acid.     They  have  generally  a  fawn  colour,  are  soluble  in  caustic  potash, 
and  precipitated  from  the  solution  by  acids.     They  also  dissolve  in  nitric 
acid  with  the  aid  of  heat ;  and  the  solution,  when  gently  evaporated  to  dry- 
ness,  leaves  a  purple  stain  of  murexide.     This  species  of  calculus  is  totally 
consumed  before  the  blowpipe,  leaving  a  mere  trace  of  ashes. 

5861.  "Urate  of  Ammonia  occasionally  forms  a  calculus,  which  is  dis- 
tinguished from  the  former  by  giving  out  ammonia  when  digested  with  pot- 
ash. 

5862.  "  Bone-earth  forms  a  common  calculus,  which  is  earthy,  soluble 
in  diluted  acids,  except  acetic  acid,  insoluble  in  potash,  and  indestructible 
by  heat. 

5863.  "  Ammoniaco-magnesian  Phosphate  also  occurs  pretty  frequently. 
It  is  the  same  double  salt  which  forms  whenever  magnesia,  phosphoric 
acid,  and  an  excess  of  ammonia,  are  brought  together.     It  is  soluble  in 
acetic  acid,  and  precipitated  again  by  ammonia.     It  has  often  a  crystalline 
aspect.     When  heated,  it  gives  off  ammonia,  and  leaves  phosphate  of  mag- 
nesia. 

5864.  "  Fusible  Calculus. — This  very  common  calculus  is  a  mixture  of 
the  two  preceding.     It  is  white  and  chalky,  and  melts  easily  before  the 
blowpipe.     Acetic  acid  dissolves  part  of  it,  hydrochloric  acid  the  rest. 

5865.  "Oxalate  of  Lime,  or  Mulberry  Calculus,  has  a  dark-coloured 
rough  surface,  and  is  very  hard.     It  is  insoluble  in  acetic  acid ;  but,  when 
heated  to  redness,  it  is  converted  into  carbonate  of  lime,  which  dissolves  in 
acids  with  effervescence. 

5866.  "  Xanthic  Oxide  is  a  rare  calculus,  first  observed  by  Dr.  Marcet. 
It  has  a  light  brown  colour,  and  becomes  resinous  by  friction.     It  dissolves 
in  caustic  potash,  and  is  precipitated  from  the  solution  by  carbonic  acid. 
It  dissolves   in  nitric  acid  without  effervescence;  and,  when  evaporated, 
leaves  a  yellow  mass.     Its  formula  is  C5  H3  N3  O2. 

5867.  "Cystic  Oxide  is  also  very  rare.     Discovered  by  Wollaston.     It 
is  yellowish-white  and  crystalline,  with  a  waxy  lustre.     It  dissolves  in 
caustic  potash,  and  is  deposited  from  the  solution  in  hexagonal  plates  on 
the  addition  of  acetic  acid.     It  also  dissolves  in  ammonia  and  the  mineral 
acids;  with  the  latter  it  forms  crystalline  compounds.     When  its  solution 
in  potash  is  heated,  ammonia  is  first  given  off,  and  afterwards  a  combusti- 
ble vapour,  with  the  odour  of  sulphuret  of  carbon.     Its  formula  is  C8  H6 
NS'O*. 

5868.  "Both  the  preceding  species  are  entirely  consumed  before  the 
blowpipe. 

5869.  "  Calculi  sometimes  occur,  in  which  layers  of  uric  acid  alternate 
with  layers  of  phosphate  of  lime,  ammoniaco-magnesian  phosphate,  and  fu- 
sible calculus. 

Changes  which  occur  during  the  Life,  Growth,  and  Nutrition  of  Vegeta- 
bles and  Animals. 

5870.  **  When  we  consider  that  the  food  of  vegetables  and  of  animals  is 
either  altogether  different  from  their  substance,  or  passes,  before  being 
assimilated,  into  a  new  form,  we  cannot  hesitate  to  admit  that  the  nutri- 
tion and  growth  of  both  classes  of  organized  beings  depend  on  chemical 
agencies,  although  these  operate  under  peculiar  conditions,  and  are  influ- 
enced by  the  unknown  force  which  we  call  Vitality,  so  as  to  produce  re- 


OP  ANIMAL  SUBSTANCES.  583 

suits  that  cannot  be  imitated  by  the  chemist  in  his  experiments  on  dead 
matter. 

5871.  "The  food  of  vegetables,    as    far  as  their  organic  structure  is 
concerned,  consists  entirely  of  inorganic  compounds ;  and  no  organized 
body  can  serve  for  the  nutrition  of  vegetables  until  it  has,  by  the  processes 
of  decay  or  putrefaction,  been  resolved  into  certain  inorganic  substances. 

5872.  "  These  are  carbonic  acid,  water,  and  ammonia,  which  are  well 
known  to  be  the  final  products  of  putrefaction.     But,  even  where  these  are 
supplied  to  vegetables,  their  growth  will  not  proceed  unless  certain  mineral 
substances  are  likewise  furnished  in  small  quantity,  either  by  the  soil,  or  in 
the  water  used  to  moisten  it.     Almost  every  plant,  when  burned,  leaves 
ashes,  which  commonly  contain  silica,  potash,  phosphate  of  lime ;  often 
also  magnesia,  soda,  sulphates,  and  oxide  of  iron.     These  mineral  bodies 
appear  to  be  essential  to  the  existence  of  the  vegetable  tissues,  so  that  plants 
will  not  grow  in  soils  destitute  of  them,  however  abundantly  supplied  with 
carbonic  acid,  ammonia,  and  water. 

5873.  "  In  the  process  of  germination,  oxygen  is  absorbed,  heat  is  given 
out,  and  in  some  cases  at  least  an  acid,  said  to  be  the  acetic,  is  formed,  the 
use  of  which  appears  to  be  to  extract -from  the  soil  the  bases  necessary  for 
the  future  progress  of  the  plant.     The  starch,  or  albumen  of  the  seed,  be- 
comes soluble,  and  in  the  juice  undergoes  certain  changes,  by  which  the 
woody  fibre  or  lignine,  required  for  the  stem  and  leaves,  is  produced ;  but, 
as  soon  as  leaves  and  roots  are  developed,  the  further  nutrition  of  the  plant 
depends  on  their  power  of  absorbing  from  the  atmosphere  and  the  soil  the 
matters  which  constitute  the  food  of  the  plant. 

5874.  "  According  to  Liebig  (see  his  Agricultural  Chemistry),  the  whole 
of  the  carbon  is  now  derived  from  carbonic  acid,  which  is  either  absorbed 
from  the  atmosphere  and  rain-water  by  the  leaves,  or  from  the  moisture 
and  air  in  the  soil  by  the  roots.     Its  carbon  is  retained,  and  its  oxygen 
given  out ;  this  decomposition  being  effected  in  the  plant  at  all  times  when 
exposed  to  the  action  of  light,  along  with  a  certain  temperature. 

5875.  "  The  hydrogen  and  oxygen  of  vegetables  are  derived  from  wa- 
ter ;  and  the  reader  will  here  observe,  that  the  great  mass  of  vegetables, 
consisting  of  lignine,  starch,  gum,  &c.   is  actually  composed  of  carbon 
plus  water. 

5876.  "  The  nitrogen  of  vegetables  is  derived  chiefly,  if  not  exclusively, 
from  ammonia,  which  is  supplied  to  them  in  rain.     Liebig  has  shown  be- 
yond all  doubt,  that  rain-water  always  contains  more  or  less  carbonate  of 
ammonia.     If  we  acidulate  pure  rain-water  with  a  little  sulphuric  acid,  and 
evaporate  to  a  small  bulk,  the  addition  of  lime  causes  the  disengagement 
of  ammonia,  easily  known  by  its  pungent  smell.     It  is  remarkable  that  the 
ammonia  of  rain-water  has  always  a  putrid  smell,  which  indicates  its  origin. 
In  fact,  it  is  derived  from  the  putrefaction  of  preceding  races  of  animals  and 
vegetables,  and  must  at  all  times  exist  in  the  atmosphere ;  although  its  rela- 
tive quantity  is  so  small,  that  it  is  not  easily  detected  until  it  has  been  accu- 
mulated in  rain,  which,  in  passing  through  the  air,  dissolves  it  readily,  and 
conveys  it  to  the  earth. 

5877.  "  It  is  also  to  be  observed,  that  the  soil  itself,  like  all  porous  bo- 
dies, possesses  the  property  of  absorbing  ammonia,  and  therefore  will  attract 
it  from  the  atmosphere.     Alumina,  peroxide  of  iron,  and  humus,  all  absorb 
ammonia  powerfully.    Gypsum  (sulphate  of  lime)  and  other  sulphates  con- 
vert the  carbonate  of  ammonia  into  the  more  fixed  sulphate,  which  remains 


584  ORGANIC  CHEMISTRY. 

in  the  soil  till  absorbed  by  the  roots.    This  explains  in  a  great  measure  the 
use  of  these  ingredients  in  fertile  soils. 

5878.  "  It  is  only  under  the  influence  of  light  that  plants  can  decom- 
pose carbonic  acid,  fixing  its  carbon  and  setting  free  its  oxygen.     During 
the  night,  on  the  contrary,  they  undergo  a  kind  of  slow  combustion,  oxygen 
being  absorbed,  and  carbonic  acid  formed.     But  the  balance  in  this  curious 
alternation  is  vastly  in  favour  of  the  process  by  which  oxygen  is  sent  into 
the  atmosphere,  for,  the  whole  carbon  of  a  forest,  for  example,  being  derived 
from  carbonic  acid,   an  equivalent  quantity  of  oxygen  must  have  been 
liberated ;  and  this  consideration  alone  enables  us  to  explain  the  fact,  that, 
notwithstanding  the  enormous  amount  of  oxygen  withdrawn  from  the  at- 
mosphere by  the  respiration  of  animals,  by  combustion,  by  putrefaction, 
and  by  the  action  of  vegetables  during  the  night,  in  all  of  which  processes 
the  oxygen  is  converted  into  carbonic  acid  of  equal  volume,  the  proportion 
of  oxygen  in  the  atmosphere  does  not  diminish,  and  that  of  carbonic  acid 
does  not  increase. 

5879.  "  From  these  considerations  it  appears  that  there  must  always 
exist  a  balance  or  fixed  proportion  between  the  existing  amount  of  animal 
and  that  of  vegetable  life.     Where  animals  abound,  and  where  men  carry 
on  the  usual  operations  of  civilized  life,  there,  carbonic  acid  must  be  largely 
formed.     But  this  carbonic  acid,  in  yielding  its  carbon  to  vegetation,  yields 
also  its  oxygen  to  restore  the  purity  of  the  air,  and  support  again  the  respi- 
ration of  men  and  animals.     Again,  the  decay  and  putrefaction  of  both  ani- 
mals and  vegetables  yield  carbonic  acid  and  ammonia,  the  very  substances 
which  form  the  food  of  a  new  race  of  vegetables ;  and  these  again  contri- 
bute to  the  nourishment  of  new  animals ;  so  that,  in  this  unceasing  round 
of  chemical  changes,  the  death  of  one  generation  supplies  the  means  of  life 
to  that  which  is  to  follow. 

5880.  "  It  has  long  been  the  prevailing  opinion,  that  the  carbon  of  plants 
is  derived  directly  from  humus  or  humic  acid  existing  in  the  soil,  which  is 
supposed  to  be  absorbed  in  the  form  of  a  solution  in  water,  or  as  humate  of 
ammonia;  but  it  must  be  admitted,  as  Liebig  has  shown,  that  there  is  no 
evidence  whatever  that  humus  is  directly  absorbed  by  plants.     Humus,  as 
it  exists  in  the  soil,  is  almost  entirely  insoluble  in  water,  and,  when  a  solu- 
ble form  occurs,  the  solution,  however  weak,  is  always  of  a  dark  brown 
colour;  whereas  the  juices  of  plants,  when  first  absorbed,  are  colourless. 
Again,  humic  acid,  as  described  by  chemists,  never  occurs  in  soils,  but  is  a 
product  of  the  action  of  alkalies  on  humus,  and  besides  forms  solutions  as 
dark-coloured  as  those  of  humus.     Good  fertile  soil  digested  with  cold  wa- 
ter yields  to  it  no  colour;  water,  filtering  through  such  soil,  passes  colour- 
less, as  may  be  daily  observed ;  nay,  moss-water,  which  is  actually  colour- 
ed brown  by  humus,  is  decolorized  by  passing  through  a  good  fertile  soil 
containing  humus;  finally,  a  peaty  soil,  which  contains  more  humus  than 
any  other,  is  notoriously  barren. 

5881.  "On  the  other  hand,  the  first  vegetables  which  grew  on  the  earth 
could  not  have  derived  their  carbon  from  humus,  which  is  a  product  of  the 
decay  of  vegetables,  but  could  only  have  obtained  it  from  carbonic  acid ; 
and  if  this  source  of  carbon  were  then  sufficient,  there  is  no  reason  to  look 
for  another.     Besides,  if  we  reflect  on  the  extreme  luxuriance  of  vegetation 
in  uninhabited  countries,  where  the  soil  has  never  been  manured,  we  cannot 
fail  to  perceive  that  the  carbon  of  that  vegetation  must  have  been  chiefly 
derived  from  the  atmosphere ;  and  when,  in  addition  to  this,  we  find  that 
the  proportion  of  humus  in  all  soils  bearing  vegetation  increases  rather  than 


OP  ANIMAL  SUBSTANCES.  585 

diminishes,  in  spite  of  the  vast  amount  of  carbon  annually  accumulated  and 
removed  in  the  crops,  we  are  compelled  to  adopt  the  same  conclusion. 

5882.  "  This  latter  consideration  shows,  that  the  humus  and  other  or- 
ganic matters  in  manures  do  not  act  directly  in  furnishing  carbon,  and  that 
their  use  chiefly  depends  on  other  ingredients.     These,  as  Liebig  has  de- 
monstrated, are,  first,  the  ammonia  they  contain  or  yield  by  putrefaction ; 
and,  secondly,  the  mineral  bodies,  such  as  potash,  phosphate  of  lime,  &c., 
found  in  their  ashes. 

5883.  "  But,  although  there  is  no  evidence  that  humus  is  directly  absorb- 
ed by  plants,  and  the  phenomena  of  peat  and  mossy  soils  prove,  that  the 
soluble  forms  of  humus  are  unfavourable  to  vegetation,  yet  it  cannot  be 
doubted  that  humus  or  mould,  both  of  the  soil  and  the  manures,  performs 
an  important  function.     It  slowly  and  gradually  undergoes  combustion, 
yielding  a  constant  and  steady  supply  of  carbonic  acid  in  moderate  quanti- 
ty.    This  is  partly  absorbed  by  the  roots,  and  partly  rises  into  the  atmos- 
phere to  be  absorbed  by  the  leaves ;  but,  as  the  proportion  of  humus  in  the 
soil  does  not  diminish,  that  which  is  thus  consumed  is  probably  restored  to 
the  soil  by  the  secretions,  or  rather  excretions,  from  the  roots. 

5884.  "  Humus  also  probably  acts  by  absorbing  and  fixing  the  ammonia 
of  the  atmosphere. 

5885.  "  According  to  the  views  above  stated,  which  have  been  admira- 
bly laid  down  by  Liebig  in  his  Agricultural  Chemistry,  the  chief  use  of 
manures  is  not  to  supply  plants  with  carbon,  but  with  ammonia  and  inor- 
ganic matters.     Every  plant  requires  certain  mineral  substances,  without 
which  it  cannot  prosper ;  and  a  soil  is  fertile  or  barren  for  any  given  plant, 
according  as  it  contains  these.     Thus,  the  ashes  of  wheat-straw  contain 
much  silica  and  potash,  while  the  ashes  of  the  seeds  contain  phosphate  of 
ammonia  and  magnesia.     Hence,  if  a  soil  be  deficient  in  any  one  of  these, 
it  will  not  yield  wheat.     On  the  other  hand,  a  good  crop  of  wheat  will  ex- 
haust the  soil  of  these  substances,  and  it  will  not  yield  a  second  crop  till 
they  have  been  restored,  either  by  manure  or  by  the  gradual  action  of  the 
weather  in  disintegrating  the  subsoil.     Hence  the  benefit  derived  from  fal- 
lows and  from  the  rotation  of  crops. 

5886.  "  When,  by  an  extraordinary  supply  of  any  one  mineral  ingre- 
dient, or  of  ammonia,  a  large  crop  has  been  obtained,  it  is  not  to  be  expect- 
ted  that  a  repetition  of  the  same  individual  manure  next  year  will  produce 
the  same  effect.     It  must  be  remembered,  that  the  unusual  crop  has  ex- 
hausted the  soil  probably  of  all  the  other  mineral  ingredients,  and  that  they 
also  must  be  restored  before  a  second  crop  can  be  obtained. 

5887.  "  The  salt  most  essential  to  the  growth  of  the  potato  is  the  double 
phosphate  of  ammonia  and  magnesia ;  that  chiefly  required  for  hay  is  phos- 
phate of  lime;  while  for  almost  all  plants  potash  and  ammonia  are  highly 
beneficial. 

5888.  "From  the  principles  above  mentioned  we  may  deduce  a  few 
valuable  conclusions  in  regard  to  the  chemistry  of  agriculture.     First.     By 
examining  the  ashes  of  a  thriving  plant,  we  discover  the  mineral  ingredients 
which  must  exist  in  a  soil  to  render  it  fertile  for  that  plant.     Secondly.     By 
examining  a  soil,  we  can  say  at  once  whether  it  is  fertile  in  regard  to  any 
plants,  the  ashes  of  which  have  been  examined.    Thirdly.    When  we  know 
the  defects  of  a  soil,  the  deficient  matters  may  be  easily  obtained  and  added 
to  it,  unmixed  with  such  as  are  not  required.      Fourthly-     The  straw, 
leaves,  &c.  of  any  plant  must  be  the  best  manure  for  that  plant,  since  every 
vegetable  extracts  from  the  soil  such  matters  alone  as  are  essential  to  it. 


586  ORGANIC   CHEMISTRY. 

This  important  principle  has  been  amply  verified  by  the  success  attending 
the  use  of  wheat-straw  or  its  ashes  as  manure  for  wheat,  and  of  the  clip- 
pings of  the  vines  as  manure  for  the  vineyard.  Where  these  are  used,  no 
other  manure  is  required.  Fifthly.  In  the  rotation  of  crops,  those  should 
be  made  to  follow  which  require  different  minerals;  or  a  crop  which  ex- 
tracts little  or  no  mineral  matter,  such  as  peas,  should  come  after  one  which 
exhausts  the  soil  of  its  phosphates  and  potash. 

5889.  "  Of  the  chemical  manures  now  so  much  used,  bone-dust  supplies 
the  phosphates,  which  have  been  extracted  by  successive  crops  of  grass  and 
corn,  the  whole  of  the  bones  of  the  cattle  fed  on  these  crops  having  been  de- 
rived from  the  soil ;  its  gelatine  also  yields  ammonia  by  putrefaction.     Gu- 
ano acts  as  a  source  of  ammonia,  containing  much  oxalate  and  urate  of 
ammonia  with  some  phosphates.     Night-soil  and  urine,  especially  the  lat- 
ter, are  most  valuable  for  the  ammonia  they  yield,  as  well  as  for  phosphates 
and  potash :  but  are  very  much  neglected  in  this  country,  although  their 
importance  is  fully  appreciated  in  Belgium  and  China.     Bran  is  a  very 
valuable  manure,  especially  for  potatoes,  as  it  contains  much  of  the  ammo- 
niaco-magnesian  phosphate. 

5890.  "  Nitrate  of  Soda  probably  acts  by  its  alkali,  replacing  potash, 
but  it  is  possible  that  its  acid  may  also  yield  nitrogen  to  plants,  although 
we  possess  at  present  no  evidence  of  this,  and  indeed  no  evidence  that 
plants  can  derive  their  nitrogen  from  any  other  source  than  from  ammonia. 

5891.  "Such  is  a  brief  sketch  of  the  general  laws  of  vegetation  as  at 
present  known,  in  so  far  as  they  are  connected  with  chemistry.     Of  the 
changes  in  the  juices  of  vegetables,  by  which  the  numerous  products  of  the 
vegetable  kingdom  are  formed,  we  know  nothing.     The  juices  of  plants 
contain  ammonia  and  sugar,  gum  or  starch ;  all  the  elements  are  therefore 
present  from  which  the  nitrogenized  compounds,  albumen,  fibrine,  and 
caseine,  in  other  words,  proteine,  may  be  formed,  and  it  appears  that  vege- 
tables alone  can  produce  proteine.     Thus  the  final  products  of  vegetation 
form  the  food  of  animals;  the  modifications  of  proteine  serving  for  nutri- 
tion, properly  so  called,  and  the  starch,  gum,  sugar,  and  oil  serving  for  the 
support  of  respiration. 

5892.  "  The  life  of  animals  is  distinguished  chemically  from  that  of 
vegetables  by  the  circumstance,  that  in  the  former  oxygen  is  constantly 
absorbed  and  replaced  by  carbonic  acid,  while  in  the  latter  carbonic  acid  is 
absorbed,  its  carbon  retained,  and  its  oxygen  given  out.    Consciousness  and 
the  power  of  locomotion  are  peculiar  to  animals. 

5893.  "  In  animals  two  processes  are  constantly  carried  on ;  that  of 
respiration,  by  which  the  animal  heat  is  kept  up ;  and  that  of  nutrition,  by 
which  the  matter  consumed  in  the  vital  functions  and  expelled  from  the 
body  is  restored. 

5894.  "  Respiration  is  essentially  a  combustion  of  carbon,  which  in  com- 
bining with  oxygen  is  converted  into  carbonic  acid,  and  at  the  same  time 
furnishes  the  animal  heat.     Liebig  calculates  that  the  amount  of  carbon 
daily  burned  in  the  body  of  an  adult  man  is  about  fourteen  ounces,  and  that 
the  heat  given  out  is  fully  sufficient  to  keep  up  the  temperature  of  the  body, 
and  to  account  for  the  evaporation  of  all  the  gaseous  matter  and  water 
expelled  from  the  lungs. 

5895.  "  This  carbon  is  derived  in  the  first  place  from  the  tissues  of 
the  body,  which  undergo  a  constant  waste,  but  ultimately  from  the  food. 

5896.  "  In  the  carnivora,  whose  food  is  almost  entirely  composed  of 
compounds  of  proteine,  albumen,   &c.  one  part  is  devoted  to  supply  the 


OF  ANIMAL  SUBSTANCES.  587 

waste  of  the  tissues,  while  another  portion,  or  a  corresponding  amount  of 
previously  existing  tissue,  is  decomposed  so  as  to  yield  the  carbon  required 
for  respiration.  As  the  tissues  can  only  be  decomposed  by  the  exercise 
of  the  vital  functions,  this  is  the  reason  why,  in  the  carnivora,  an  enor- 
mous amount  of  muscular  motion  is  required  to  furnish  the  necessary  sup- 
ply of  carbon. 

5897.  "  On  the  other  hand,  the  food  of  the  herbivora  contains  but  little 
of  the  compounds  of  proteine,  only  sufficient  to  restore  the  waste  of  the 
tissues ;  while  the  carbon  required  for  respiration  is  supplied  by  the  starch, 
gum,  sugar,  oil,  &c.  which  form  the  great  mass  of  their  food,  and  no  such 
amount  of  muscular  motion  is  required  in  them  as  in  the  carnivora. 

5898.  "  It  is  in  the  form  of  bile  chiefly  that  the  carbon  undergoes  com- 
bustion.    Hitherto,  the  true  function  of  the  bile  has  been  disputed;  and  by 
most  authors  that  fluid  has  been  considered  as  an  excretion,  intended  to  be 
expelled  from  the  body  in  the  fseces.     But  Liebig  has  shown  that  only  a 
small  fraction  of  the  whole  amount  of  bile  can  be  detected  in  any  shape  in 
the  fseces,  and  that  the  bile  unquestionably  is  reabsorbed  in  the  intestinal 
canal,  and  re-enters  the  circulation,  where  it  soon  disappears ;  and  as  the 
proportion  of  carbon  in  the  bile  is  very  large,  although  not  sufficient  to 
account  for  all  the  carbonic  acid  given  out,  there  is  no  reason  to  doubt  that 
it  is  gradually  consumed  by  the  oxygen  of  the  arterial  blood,  and  convert- 
ed into  carbonic  acid  and  water,  which  escape  by  the  lungs  and  skin. 

5899.  "  To  return  to  the  subject  of  the  animal  heat :  the  food  that  is 
required,  and  hence  the  appetite,  must  be  proportional  to  the  amount  of 
carbon  required  to  supply  the  animal  heat.     Now,  in  hot  climates,  where 
the  external  cooling  is  less,  less  heat  is  required,  the  appetite  is  much  more 
feeble,  and  the  usual  food,  consisting  of  fruits  and  vegetables,  contains  a 
far  smaller  amount  of  carbon  than  in  cold  climates,  where  the  appetite  is 
keen,  and  the  food  highly  carbonized,  such  as  flesh,  or  even  blubber.     For 
the  same  reasons,  warm  clothing,  by  diminishing  the  loss  of  heat  by  ex- 
ternal cooling,  blunts  the  appetite ;  and  those  who  remove  from  a  cold  to  a 
warm  climate  always  find  that  their  appetite  fails.     This  is  a  warning  from 
nature  to  diminish  the  amount  of  food  taken ;  and  if  it  were  attended  to, 
and  the  common  but  absurd  practice  of  stimulating  the  appetite  by  ardent 
liquors  and  hot  spices  abandoned,  Europeans  might  enjoy  as  good  health 
in  the  East  or  West  Indies  as  at  home.    It  is  obvious  that,  even  in  Europe, 
more  food  is  required  in  winter  than  in  summer.  (Animal  Chemistry,  23.) 

5900.  "  In  endeavouring  to  explain  the  formation  of  the  bile,  it  is  ob- 
viously of  no  moment  whether  we  derive  it  from  the  albumen,  fibrine,  &c. 
of  the  food,  or  those  of  the  tissues,  their  composition  being  identical.    Liebig, 
assuming  choleic  acid  to  be  the  chief  organic  constituent  of  the  bile,  and  its 
formula  to  be  C78NaH86O23,  has  shown  that  the  half  of  this  formula,  added 
to  that  of  urate  of  ammonia,  C10H5N7O8,  which  gives  the  sum  C48N6 
H40  O17,  is  equal  to  the  formula  of  blood  or  flesh,  C48  N6  H39  O15,  with  the 
addition  of  one  atom  water  and  one  atom  oxygen.  (Animal  Chemistry,  135, 
136.)     Again,  proteine,  C48N6H36O14,  plus  three  atoms  of  water,  gives 
the  same  sum,  excepting  one  atom  of  hydrogen,  viz.  C48N8H39O17.     In 
this  way  we  can  see  how  the  tissues,  acted  on  by  oxygen  and  water,  may 
yield  the  ingredients  of  bile  and  urine.     This  is  the  first  attempt  which  has 
been  made  to  trace  chemically  the  connection  between  the  food,  the  blood 
or  the  tissues,  and  the  secretions  or  excretions ;  and  showing,  as  it  does, 
that  these  questions  are  capable  of  elucidation  on  chemical  principles,  it 

75 


588  ORGANIC  CHEMISTRY. 

must  be  regarded  as  the  most  important  idea  yet  suggested  in  animal  che- 
mistry. 

5901.  "  Supposing  it  to  be  well-founded,  the  tissues  which  are  consumed 
are  resolved  first  into  bile  and  urate  of  ammonia.     The  former  is  secreted 
from  the  liver,  reabsorbed  and  burned,  as  before  stated.    The  latter,  in  ser- 
pents and  birds,  is  expelled  unchanged ;  but  in  man  and  quadrupeds,  in 
whom  the  amount  of  oxygen  inspired  is  much  greater,  it  is  also  oxidized, 
yielding  finally  carbonic  acid,  ammonia,  and  urea. 

5902.  "  Should  the  supply  of  oxygen  in  the  human  subject  be  insuffi- 
cient to  act  on  the  urate  of  ammonia,  then  the  uric  acid  is  deposited  as 
gravel  or  calculus  ;  if  the  supply  of  oxygen  be  somewhat  greater,  but  still 
deficient,  oxalic  acid  is  the  result,  and  mulberry  calculus  occurs ;  but,  if 
much  exercise  be  taken  and  abundance  of  oxygen  supplied,  the  oxidation 
of  the  uric  acid  is  completed,  and  nothing  is  left  but  urea  or  carbonate  of 
ammonia. 

5903.  "  This  explains  the  true  cause  of  uric  acid  and  mulberry  calculus 
to  be  a  deficiency  of  oxygen;  it  also  explains  why  uric  acid  calculus  is  fol- 
lowed by  mulberry  calculus  in  those  who  remove  from  the  town  to  the 
country,  where  more  exercise  is  taken ;  and  from  these  considerations  we 
may  see  how  valuable  are  the  results  which  will  flow  from  a  thorough  in- 
vestigation of  all  departments  of  animal  chemistry. 

5904.  "  The  urine  of  the  herbivora  differs  from  that  of  man,  in  contain- 
ing, besides  urea,  hippuric  acid  when  they  are  at  rest  or  stall-fed,  and  ben- 
zoic  acid   when  they  are  in  full  exercise,  and  when  consequently  more 
oxygen  is  supplied.     Liebig  has  shown,  that,  if  to  five  times  the  formula  of 
blood,  we  add  nine  atoms  of  oxygen,  we  have  the  elements  of  six  atoms 
hippuric  acid,  nine  atoms  urea,  three  atoms  choleic  acid,  three  atoms  am- 
monia, and  three  atoms  water;  and  that,  if  to  five  times  the  formula  of 
blood  we  add  forty-five  atoms  oxygen,  we  obtain  the  elements  of  six  atoms 
benzoic  acid,  thirteen  and  a  half  atoms  urea,  three  atoms  choleic  acid,  fifteen 
atoms  carbonic  acid,  and  twelve  of  water.     Moreover,  two  atoms  proteine, 
with  two  atoms  of  water,  contain  the  elements  of  six  atoms  allantoine  (found 
in  the  urine  of  the  foetal  calf),  and  one  atom  choloidic  acid,  which  is  sup- 
posed to  be  the  same  as  the  meconium. 

5905.  "  The  bile  of  the  herbivora  is  much  more  abundant  than  that  of 
the  carnivora,  an  ox  secreting,  according  to  Burdach,  37lbs.  of  bile  daily. 
As  the  waste  of  matter  in  the  herbivora  is  but  limited,  it  is  obvious  that  it 
cannot  supply  all  the  bile,  and  consequently  a  great  part  of  it  must  be  de- 
rived from  the  starch  and  other  nonazotized  constituents  of  their  food,  which 
lose  oxygen,  and  enter  into  combination  with  some  azotised  product  of  the 
decomposition  of  compounds  of  proteine. 

5906.  "  In  order  to  show  how  this  is  possible,  Liebig  points  out  that  the 
elements  of  two  atoms  of  proteine,  with  those  of  three  atoms  uric  acid  and 
two  atoms  oxygen,  amount  to  the  same  sum  as  six  atoms  hippuric  acid  and 
nine  atoms  urea ;  while,  if  to  five  atoms  starch  we  add  two  atoms  hippuric 
acid  and  two  atoms  oxygen,  the  sum  is  equal  to  two  atoms  choleic  acid  and 
twenty  atoms  carbonic  acid. 

5907.  "  Again,  if  the  elements  of  proteine  and  starch,  oxygen  and  water 
being  present,  undergo  transformation,  and  mutually  affect  each  other,  the 
products  of  this  metamorphosis  may  be  urea,  choleic  acid,  ammonia,  and 
carbonic  acid.     Thus : 


OP  ANIMAL  SUBSTANCES.  589 

5  atoms  proteine,  5  (C«  N* H™ O")  =  C*°  Nao H'80 O™ 
15      „      starch,     15  (C»*       H'°O'°)  =  Oe<>        H'5°O'«> 

H'2 


And 

5      „      oxygen, 

=                        05 

The  sum  is 

—  -  c-120  N30  H342  O837. 

9  atoms  choleic  acid, 
9      „      urea, 
3      „      ammonia, 
60      „      carbonic  acid, 

9 
9 
3 
60 

(ON 
(C2  NS 
C      N 
(C 

H33Q") 

H3            ) 

02) 

—  C342  N9 

=             N3 
--60 

H297Q99 

H9 

Q120 

The  sum  is =  020  N3°  H^  Q237 

5908.  "  The  reader  will  observe  that  these  equations  are  given,  not  as 
representing  what  is  actually  proved  to  occur,  but  only  to  show  how  such 
changes  may  be  conceived  on  ordinary  chemical  principles.    But  it  is  to  be 
borne  in  mind,  that  all  the  necessary  substances  meet  in  the  circulation ; 
proteine  and  starch  from  the  food,  oxygen  in  the  arterial  blood,  and  that 
water  is  never  absent:  while  the  resulting  products  are  the  chief  constituents 
of  the  secretions  and  excretions;  viz.  carbonic  acid,  excreted  by  the  lungs; 
urea  and  carbonate  of  ammonia,  excreted  by  the  kidneys;  and  choleic  acid, 
secreted  by  the  liver.  (Animal  Chemistry,  150  et  seq.) 

5909.  "  We  have  thus  seen  how  the  carbon  in  the  form  of  choleic  acid 
or  bile,  may  be  obtained  in  a  state  most  favourable  for  its  oxidation  or  com- 
bustion.   But,  if  the  supply  of  oxygen  be  deficient,  the  choleic  acid  may  by 
a  partial  oxidation  yield  hippuric  and  lithofellic  acids,  just  as  we  have  seen 
that  uric  acid,  partially  oxidized,  yields  oxalic  acid  ;  for  two  atoms  choleic 
acid  +10  atoms  oxygen  are  equal  to  two  atoms  hippuric  acid,  one  atom 
lithofellic  acid,  and  fourteen  atoms  water.    Thus  one  species  of  biliary  cal- 
culus, identical  with  the  bezoar  stones  found  in  the  herbivora,  may  have  an 
origin  similar  to  that  of  the  mulberry  calculus,  both  arising  from  a  deficient 
supply  of  oxygen.  (Liebig.) 

5910.  "  Soda  is  necessary  to  the  formation  of  bile,  and  is  supplied  in 
the  form  of  common  salt.    Where  the  supply  of  soda  is  defective,  the  meta- 
morphosis of  proteine  can  yield  only  fat  and  urea.     If  we  assume  for  fat 
the  empirical  formula  C11  H10O,  then  two  atoms  proteine,  with  twelve  atoms 
water,  and  fourteen  atoms  oxygen,  in  all  C96N13H84O54,  are  equal  to  six 
atoms  urea,  six  atoms  fat,  and  eighteen  atoms  carbonic  acid.    If  we  assume 
fat  to  be  CiaH10O,  a  similar  result  may  be  traced  ;  and  the  composition  of 
all  fats  lies  between  these  two  empirical  formula?.    Now,  it  is  worthy  of  ob- 
servation, that,  if  we  wish  to  fatten  an  animal,  we  must  carefully  avoid 
giving  much  salt  in  its  food.  (Liebig.) 

5911.  "  As  another  point  of  connection  between  the  products  of  the  me- 
tamorphosis of  bile  and  of  the  constituents  of  urine,  in  addition  to  the  pos- 
sibility already  mentioned  of  both  being  derived  from  the  oxidation  of  pro- 
teine, it  may  here  be  remarked,  that  three  atoms  taurine  and  three  atoms 
ammonia  are  equal  to  one  atom  uric  acid,  one  atom  urea,  and  twenty-two 
atoms  water;  and  that  one  atom  taurine  and  one  atom  ammonia  are  equal 
to  one  atom  allantoine  and  seven  atoms  water.  (Liebig.) 

5912.  "  It  may  further  be  noted  that  one  atom  uric  acid,  fourteen  atoms 
water,  and  two  atoms  oxygen,  correspond  to  two  atoms  taurine  and  one 
atom  urea;  or,  if  two  atoms  water  be  added,  to  two  atoms  taurine  and  two 
atoms  carbonate  of  ammonia.     Moreover,  one  atom  alloxan  and  ten  atoms 


590  ORGANIC  CHEMISTRY. 

water  are  equal  to  two  atoms  taurine ;  and  one  atom  taurine  contains  the 
elements  of  two  atoms  oxalic  acid,  one  atom  ammonia,  and  four  atoms  wa- 
ter. (Liebig.) 

5913.  "  As  alloxan  is  a  product  of  the  oxidation  of  uric  acid,  and  as  it 
has  been  shown  above  to  be  related  to  taurine,  that  is,  to  bile,  it  would  be 
very  important  to  study  its  action  on  the  system.     It  might  probably  act 
beneficially  in  some  diseases  of  the  liver.     It  may  be  safely  administered  in 
considerable  quantity.  (Liebig.) 

5914.  "  In  the  urine  of  the  carnivora  we  find  soda  in  moderate  quantity, 
combined  with  sulphuric  and  phosphoric  acids.     This  soda  was  contained 
in  their  food,  and,  after  contributing  to  form  the  bile,  has  been  secreted  by 
the  kidneys.     But  it  is  never  sufficient  to  neutralize  the  acids  produced, 
and  consequently  we  find  much  ammonia  along  with  it,  while  the  urine  is 
acid. 

5915.  "But  in  the  urine  of  the  herbivora  soda  is  present  in  far  larger 
quantity,  and  combined  with  carbonic,  hippuric,  or  benzoic  acid.     This 
shows  that  the  herbivora  require  a  far  greater  amount  of  soda  than  is  con- 
tained in  the  amount  of  blood  daily  consumed,  which  in  them  is  small ;  and 
this  soda  is  obtained  from  their  food,  and  employed  in  producing  their  abun- 
dant bile. 

5916.  "  The  plants  on  which  the  herbivora  feed  cannot  grow  in  a  soil 
destitute  of  alkalies;  but  these  alkalies  are  not  less  necessary  for  the  sup- 
port of  the  animals  than  of  the  plants.     The  soda  is  found  in  the  blood  and 
bile ;  and  the  potash  is  now  known  to  be  absolutely  essential  to  the  produc- 
tion of  caseine,  that  is,  the  secretion  of  milk.    In  like  manner,  the  phosphate 
of  lime,  which  is  essential  to  the  growth  of  grasses,  is  equally  essential  to 
the  production  of  bone  in  the  animals  which  feed  on  these  plants.    It  is  im- 
possible not  to  be  penetrated  with  admiration  of  the  wisdom  which  is  shown 
in  these  beautiful  arrangements. 

5917.  "  Let  us  now  consider  the  changes  which  the  food  undergoes  in 
the  process  of  digestion,  and  we  shall  observe  this  process  in  the  carnivora, 
where  it  is  most  simple,  as  their  food  is  identical  in  composition  with  their 
tissues. 

5918.  "  When  the  food  has  entered  the  stomach,  the  gastric  juice  is 
poured  out,  and  after  a  short  time  the  whole  is  converted  into  a  semifluid, 
homogeneous  mass,  the  chyme.     Many  researches  have  been  made  to  dis- 
cover the  solvent  contained  in  the  gastric  juice,  but  in  vain.    It  contains  no 
substance  which  has  the  property  of  dissolving  fibrine,  albumen,  &c.;  and 
we  are  compelled  to  adopt  the  opinion  of  Liebig,  according  to  which  the 
food  is  dissolved  in  consequence  of  a  metamorphosis,  analogous  to  fermen- 
tation, by  which  a  new  arrangement  of  the  particles  is  effected.     As,  in 
fermentation,  the  change  is  owing  to  the  presence  of  a  body  in  a  state  of 
decomposition,  or  motion,  which  is  propagated  from  the  ferment  to  the  sugar 
by  contact;  so,  in  digestion,  the  gastric  juice  contains  a  small  quantity  of  a 
matter  derived  from  the  lining  membrane  of  the  stomach,  which  is  in  a  state 
of  progressive  change,  and  the  change  or  motion  is  propagated  from  this  to 
the  particles  of  the  food  under  certain  conditions,  such  as  a  certain  tempe- 
rature, &c. 

5919.  "  The  phenomena  of  artificial  digestion  confirm  this  view.     If  the 
lining  membrane  of  a  stomach,  perfectly  clean  and  fresh,  be  infused  in  wa- 
ter feebly  acidulated  with  chlorohydric  acid,  the  liquid  acquires  no  solvent 
action  on  albumen ;  but  if  the  membrane  be  exposed  to  the  air  for  some 
time,  or  be  left  in  water  for  a  while, — in  short,  if  decomposition  be  allowed 


OF  ANIMAL  SUBSTANCES.  591 

to  commence, — then  the  infusion,  if  coagulated  albumen  or  fibrine  be  placed 
in  it,  and  the  whole  kept  at  the  temperature  of  the  body,  by  degrees  effects 
a  perfect  solution  or  digestion. 

5920.  "  Prout  has  shown  that  the  gastric  juice  contains  free  chlorohy- 
dric  acid.     This  is  derived  from  the  common  salt,  the  soda  of  which  com- 
bines with  the  albumen  or  fibrine,  while  its  acid,  being  set  free,  at  length 
by  its  accumulation  checks  further  change.     Besides  the  gastric  juice,  the 
only  other  substance  employed  in  digestion  is  the  oxygen  which  is  intro- 
duced into  the  stomach  with  the  saliva,  which  from  its  viscidity  encloses  a 
large  quantity  of  air.     The  chyme  then  leaves  the  stomach,  and  gradually 
passes  into  the  state  of  chyle,  which  resembles  blood,  except  in  colour,  being 
already  alkaline,  not  acid  like  the  chyme. 

5921.  "  By  means  of  the  circulation  oxygen  is  conveyed  in  the  arterial 
blood  to  every  part  of  the  body.     This  oxygen,  acting  on  the  tissues  des- 
tined to  undergo  change,  produces  a  metamorphosis,  by  which  new  soluble 
compounds  are  formed.     The  tissues  thus  destroyed  are  replaced  by  the 
new  matter  derived  from  the  food.     Meantime,  those  of  the  products  of  me- 
tamorphosis which  contain  the  principal  part  of  the  carbon,  are  separated 
from  the  venous  blood  in  the  liver,  and  yield  the  bile;  while  the  nitrogen 
accumulates,  and  is  separated  from  the  arterial  blood  in  the  kidneys  in  the 
form  of  urea  or  uric  acid. 

5922.  "  It  has  been  already  mentioned,  that  vegetables  alone  possess  the 
power  of  forming  proteine,  which  they  furnish  to  animals  in  the  forms  of 
albumen,  fibrine,  and  caseine.     In  the  animal  body  these  forms  of  proteine 
are  employed  to  yield  the  different  tissues,  most  of  which  bear  a  simple  re- 
lation to  proteine.     Thus, — 

Fibrine,  albumen,  caseine,  are  Pr  +  S  -f-  P  +  salts. 

Arterial  membrane  is          -  -  Pr  -j-  2HO. 

Chondrine  is      -         -        -  -  Pr-f  4HO -}- (X 

Hair,  horn,  &c.,  are            -  -  Pr  +  NH3  -f  Q3. 

Gelatinous  tissues  are         -  -  2Pr  -f  3NR3  +  HO  -j-  (X 

5923.  "  It  is  not  meant  that  these  formulas  express  the  actual  constitution 
of  the  tissues,  but  only  that  they  give  the  proportion  of  the  elements  actually 
present,  and  show  how  they  might  give  rise  to  the  tissues.     Some  of  these 
tissues  contain  proteine,  or  at  least  yield  it  when  acted  on  by  potash :  this 
is  the  case  with  hair  and  horn.    But  others,  as,  for  example,  the  gelatinous 
tissues,  although  doubtless  derived  from  proteine,  do  not  contain  it,  and  con- 
sequently cannot  yield  any  of  its  modifications.     This  explains  the  fact 
that  gelatine  alone  cannot  support  animal  life.     It  cannot  yield  blood  or 
muscular  fibre,  although  it  may  serve  to  nourish  the  gelatinous  tissues. 
(See  Gelatine.) 

5924.  "Liebig  has  shown  (Animal  Chemistry,  p.  141),  that  gelatine 
may  be  formed  from  proteine  in  two  ways;  either  by  adding  to  two  atoms 
proteine  three  atoms  allantoine  and  three  atoms  water  (which  are  equal  to 
one  atom  uric  acid,  one  atom  urea,  and  four  of  water),  or  by  subtracting 
from  three  atoms  proteine  half  an  atom  choloidic  acid,  and  adding  four 
atoms  water.     These  statements  apply  to  Mulder's  formula  for  gelatine; 
but  as  the  true  formula  is  still  doubtful,  they  are  only  mentioned  to  show 
the  method  by  which  we  may  hope  to  arrive  at  accurate  results. 

5925.  "  There  is  another  constituent  of  the  animal  body,  namely  fat,  the 
production  of  which  deserves  notice.     It  is  not  an  organized  tissue,  but  is 
formed  and  collected  in  the  cellular  tissue  under  certain  circumstances. 


592  ORGANIC  CHEMISTRY. 

These  are  rest  and  confinement,  that  is,  a  deficiency  of  oxygen,  and  an 
abundance  of  food  devoid  of  nitrogen.  Carnivorous  animals  are  never  fat; 
and  the  herbivora  only  become  so  in  confinement. 

5926.  "  Now  the  chief  source  of  fat  is  starch,  or  sugar,  the  composition 
of  which  is  such,  that,  if  deprived  of  oxygen,  fat  remains.     If  from  starch, 
Cia  H10  O10,  we  take  nine  atoms  oxygen,  there  remains  C13  H10  O,  which 
is  one  of  the  empirical  formulae  for  fat.     Or  if  from  starch  we  remove  one 
atom  carbonic  acid,  CO2,  and  seven  atoms  oxygen,  the  remainder,  C11  H10  O, 
represents  the  other  empirical  formula  of  fat.     We  have  already  seen  how 
fat  may  be  derived  from  proteine  when  soda  is  deficient ;  and  we  may  here 
add,  that  all  the  elements  of  food  contain  more  oxygen  than  fat,  in  propor- 
tion to  the  carbon.     Thus,  in  albumen,  fibrine,  and  caseine,  for  120  eq. 
carbon  there  are  contained  36  eq.  oxygen;  in  starch,  for  120  eq.  carbon, 
100  eq.  oxygen;  in  sugar  and  gum,  110  eq.  oxygen;  in  sugar  of  milk,  120 
eq.;  and  in  grape-sugar,  140  eq.  oxygen;  while  in  fat  there  are  only  10  eq. 
oxygen  for  120  eq.  carbon. 

5927.  "  It  is  obvious,  therefore,  that  fat  can  only  be  formed  by  a  process 
of  deoxidation.     But  we  have  seen  that  it  is  produced  where  oxygen  is  de- 
ficient ;  and  it  appears,  as  Liebig  has  pointed  out,  that  when  there  is  a  defi- 
cient supply  of  oxygen,  the  production  of  fat,  which  is  the  consequence  of 
this  deficiency,  yields  a  supply  of  that  element,  and  thus  serves  to  keep  up 
the  animal  heat  and  the  vital  functions,  which  would  otherwise  be  arrested. 
This  is  another  beautiful  instance  of  contrivance,  equally  simple  and  won- 
derful. 

5928.  "  That  fat  must  be  formed  by  the  deoxidizing  process  above  al- 
luded to,  is  proved  by  the  phenomena  of  the  fattening  of  animals.     A 
goose,  tied  up,  and  fed  with  farinaceous  food  altogether  destitute  of  fat,  ac- 
quires, in  a  short  time,  an  increase  in  weight  of  several  pounds,  the  whole 
of  which  is  fat.     Again,  the  bee  produces  wax,  a  species  of  fat,  from  pure 
sugar. 

5929.  "  With  regard  to  the  production  of  nervous  matter,  which  animals 
alone  can  form,  we  see,  from  its  composition,  intermediate  between  that  of 
proteine  and  fat,  that  it  may  be  formed,  either  by  depriving  proteine  of 
some  nitrogenated  product,  or  by  adding  such  a  product  to  fat.     Where  it 
is  formed  we  do  not  know ;  but  it  must  be  formed  in  the  animal  body :  and 
Liebig  has  suggested  that  the  power  of  the  vegetable  alkalies  to  affect  the 
nervous  system,  may  be  owing  to  their  composition,  which  approaches 
nearer  to  that  of  nervous  matter  than  any  other  compounds.     These  alka- 
lies may  promote  or  check  the  formation  of  nervous  matter,  and  thus  pro- 
duce their  peculiar  effects. 

5930.  "  In  like  manner,  certain  vegetable  products  analogous  to  the  ve- 
getable alkalies,  such  as  caffeine  (or  theine)  and  theobromine,  may  be  sup- 
posed, according  to  Liebig,  to  promote  the  secretion  of  bile,  their  compo- 
sition being  related  to  that  of  some  of  the  products  of  bile. 

5931.  "Thus  one  atom  caffeine  (or  theine),  with  nine  atoms  water  and 
nine  atoms  oxygen,  may  yield  two  atoms  taurine.     Again,  one  atom  theo- 
bromine, with  twenty-two  atoms  water  and  sixteen  atoms  oxygen,  corres- 
ponds to  four  atoms  taurine  and  one  atom  urea;  or  one  atom  theobromine, 
eight  atoms  water,  and  fourteen  atoms  oxygen,  contain  the  elements  of  two 
atoms  taurine  and  one  atom  uric  acid.     (Animal  Chemistry,  180.) 

5932.  "  Now  it  is  surely  very  remarkable,  that  the  vegetables  containing 
these  compounds,  tea,  coffee,  and  cocoa,  should  be,  one  or  other  of  them, 
used  by  almost  all  nations  to  yield  a  refreshing  drink;  and  it  is  still  more 


OF  RESPIRATION.  593 

curious  that  the  peculiar  principle  of  tea  should  turn  out  to  be  identical  with 
that  of  coffee,  as  recent  researches  have  demonstrated. 

5933.  "  We  may  suppose,  with  some  degree  of  probability,  that  where 
the  formation  of  bile,  and  consequently  that  of  urine,  which  is  connected 
with  it,  does  not  go  on  as  it  ought,  the  use  of  these  beverages,  by  promoting 
the  secretion  of  bile,  may  assist  the  process  of  respiration,  promoting  the 
animal  heat,  and,  at  the  same  time,  contributing  to  the  due  performance  of 
all  the  vital  functions.     At  all  events,  neither  the  beneficial  and  refreshing 
effects  of  these  articles  of  diet,  nor  their  relation  to  bile  and  urine,  can  be 
overlooked ;  and  the  universal  adoption  of  the  practice  of  using  tea,  coffee, 
or  chocolate,  is  a  proof  that  men  have  discovered  and  obtained  from  dif- 
ferent sources  the  means  of  producing  the  same  effect. 

5934.  "  The  preceding  observations  are  sufficient  to  show  that  we  may 
expect,  in  progress  of  time,  to  explain  the  action  of  all  remedies  on  chemical 
principles.     The  true  path  has  been  opened  up,  and  it  only  remains  for  ex- 
perimenters to  pursue  it  with  energy  and  perseverance." 

OF  RESPIRATION. 

5935.  The  quotation  from  Gregory's  work  being  con- 
cluded, I  subjoin  an  article  which  I  had  prepared  on  respi- 
ration, as  it  contains  some  ideas  which  are  not  found  in 
the  preceding  matter,  and  some  objections  to  Liebig's  ex- 
planation of  the  phenomena  of  that  process. 

5936.  Chemistry  demonstrates,  that  during  this  process, 
the  volume  of  the  air  respired  by  animals  is  diminished, 
but  that  a  portion  of  the  oxygen  is  replaced  by  an  equal 
bulk  of  carbonic  acid.     Although,  at  one  time,  by  respect- 
able observers,  the  volume  of  this  last  mentioned  gas  was 
alleged  not  to  be  uniformly  equal  to  that  of  the  absorbed 
oxygen,  the  ratio  of  the  one  to  the  other,  being  represented 
as  varying  with  the  time  of  day  and  the  season,  not  only 
in  different  animals,  but  also  in  the  same  animal,  later  ob- 
servation seems  to  have  produced  a  general  opinion,  which 
is  zealously  espoused  by  the  distinguished  chemist  above 
mentioned,  that  the  expired  carbonic  acid  is,  upon  the 
whole^  exactly  equivalent  to  the  oxygen  consumed. 

5937.  The  prevalence  of  nitrogen,  in  animal  substances, 
naturally  led  to  the  idea  that  it  might  be  assimilated  more 
or  less  during  respiration;  but  experience  has  led  to  an 
opposite  opinion;  and  Liebig  has  endeavoured  to  show, 
that  in  the  nutriment  of  granivorous  animals,  there  is  no 
deficiency  of  vegeto-animal  matter  having  as  large  a  pro- 
portion of  nitrogen  as  flesh  and  blood*  (5023). 

*  I  subjoin  the  following  opinion  of  Berzelius.     Report  for  1840,  page  313. 
"  The  question  has  often  been  put,  whether  animals  assimilate  nitrogen  during 
respiration.     In  examining  air  which  has  been  breathed  by  them,  it  has  been  found 


594  ORGANIC  CHEMISTRY. 

5938.  When  first,  by  the  Lavoiserian  school,  the  heat 
of  all  ordinary  fires  was  shown  to  be  attributable  to  the 
union  of  oxygen  with  the  combustible  employed,  the  idea 
naturally  followed,  that  respiration  being  attended  by  a 
like  union  of  oxygen  with  combustible  matter,  animal  heat 
ought  to  be  ascribed  to  this  source.     Many  objections  to 
this  explanation  of  the  origin  of  animal  heat  were  subse- 
quently urged,  and,  among  others,  the  fact  that  the  heat 
of  the  lungs,  the  fire  place,  is  no  higher  than  remoter  parts 
of  the  animal  frame. 

5939.  To  remove  this  objection,  Crawford  suggested 
that  the  capacity  for  heat,  of  arterial  blood,  being  greater 
than  that  of  venous  blood,  caloric  was  taken  up  by  the 
blood  in  one  state,  to  be  evolved  when  in  the  other.     This 
suggestion  respecting  the  relative  capacities  for  heat,  of 
arterial  and  venous  blood,  has  not  been  supported  by  sub- 
sequent experience;  and  another  view  of  the  subject  has 
been  taken,  which  renders  it  quite  consistent  that  the  tem- 
perature should  not  be  peculiarly  high  in  the  lungs. 

5940.  It  is  supposed  that  the  blood  merely  absorbs  oxy- 
gen in  the  lungs,  but  that  this  oxygen  is  carbonized  during 
its  circulation,  and  thus  causes  heat  to  be  given  out  in  all 
parts  of  the  system.    The  carbonic  acid  thus  produced,  on 
reaching  the  lungs  in  combination  with  the  venous  blood, 
is  exchanged  for  oxygen,  and  consequently  expired  with 
the  breath. 

5941.  Liebig  conceives  that  the  iron  in  the  hematosin 
of  the  red  globules  is  held  by  the  arterial  blood,  in  the 
state  of  hydra  ted  sesquioxide;  but  in  the  capillaries,  the 
sesquioxide  passing  to  the  state  of  protoxide,  by  yielding 
oxygen  to  the  carbon  in  the  blood,  combines  with  the  ear- 
that  in  some  cases  a  deficit  of  nitrogen  has  ensued,  in  others  an  excess,  while  in 
others,  again,  the  proportion  has  remained  unchanged.     Yet  rigorous  experiments 
have  proved,  that  the  nitrogen  of  respired  air  is  quite  passive,  and  cannot  be  assimi- 
lated during  respiration  :  moreover,  that  the  blood,  in  common  with  all  other  liquids 

in  contact  with  the  air,  contains  nitrogen  and  oxygen  in  the  proportion  in  which 
they  are  present  in  the  gaseous  mixture  employed ;  so  that  when  a  mixture,  con- 
taining  more  nitrogen,  is  respired,  a  greater  quantity  is  absorbed.  When  the  mix- 
ture, under  like  circumstances,  has  an  inferior  quantity  of  nitrogen,  this  principle  is 
given  out  by  the  blood.  It  may  be  assumed,  that  experiments  have  completely  de- 
cided that  the  proportion  of  nitrogen  in  the  animal  frame  is  altogether  independent 
of  the  quantity  of  air  respired." 

It  does  not,  however,  appear  to  me  to  be  true,  that  all  liquids  in  contact  with  air 
take  up  its  ingredients  in  the  same  proportion ;  or  if  they  do,  that  they  continue  to 
hold  them  in  that  proportion,  uninfluenced  by  the  chemical  affinity  between  their 
constituents  and  oxygen. 


OF  RESPIRATION.  595 

bonic  acid  thus  produced,  and  gives  rise,  in  the  venous 
blood,  to  a  carbonated  protoxide. 

5942.  When  the  venous  blood  reaches  the  lungs,  the 
protoxide  exchanging  carbonic  acid  for  oxygen,  this  gas  is 
expelled  with  the  breath,  while  the  regenerated  sesquioxide 
is  again,  by  union  with  water,  reconverted  into  a  hydrate. 
The  well  known  change  of  hue  which  follows  the  transfer 
of  the  blood  from  the  veins  to  the  arteries,  through  the 
pulmonary  organs,  seems  to  be  considered  as  a  collateral 
consequence  of  these  chemical  reactions.    Yet  this  change 
does  not  appear  to  me  sufficiently  accounted  for,  since  no 
such  alteration  of  colour  can  be  produced  by  the  transfor- 
mation of  a  carbonated  protoxide  of  iron  to  a  hydrated 
sesquioxide.    Moreover,  the  fact  that  no  peculiar  elevation 
of  temperature  takes  place  on  the  surfaces  where  the  ve- 
nous blood  meets  the  breath,  seems  to  me  inconsistent 
with  Liebig's  explanation,  since  the  heat  must  be  extri- 
cated in  the  space  where  the  iron  is  peroxidized. 

5943.  Upon  the  whole  I  now  think  as  1  have  for  forty 
years,  whatever  other  opinions  may  have  prevailed,  that 
there  must  be  a  degree  of  heat  derived  from  respiration 
proportioned  to  the  quantity  of  oxygen  converted  into  car- 
bonic acid;  but  with  all  due  deference  for  Liebig,  I  do  not 
agree  with  him,  that  it  is  possible  to  give  a  satisfactory 
explanation  of  this  process  upon  purely  chemical  affinities, 
such  as  exist  independently  of  vital  power.     It  appears  to 
me  that  nature  has  the  power,  within  certain  limits,  of 
making  chemical  affinities  to  suit  her  own  purposes,  and 
can  therefore  cause  the  oxygen  to  be  absorbed,  the  carbon 
to  combine  therewith,  and  the  heat  to  be  given  out  when 
and  where  the  processes  of  vitality  require  it.     If  nature 
have  not  the  alleged  power,  how  does  it  happen  that,  out 
of  the  heterogeneous  congeries  of  elements  existing  in  the 
egg,  the  bill,  the  claws,  the  feathers,  the  bones,  the  blood, 
and  flesh,  are  made  to  appear  at  the  various  stations,  at 
which  their  presence  is  requisite,  for  the  existence  of  a 
young  bird?* 

*  Mr.  Winn,  (L.  and  E.  Phil.  Mag.  174,)  considers  the  extension  and  contraction  of 
the  fibrous  tissues  of  the  arteries,  during  pulsation,  as  among  the  causes  of  animal 
heat.  It  is  well  known  that  caoutchouc  grows  warm  when  rapidlj  extended ;  and 
Mr.  Winn  found  a  portion  of  the  aorta  of  an  ox  to  be  capable  of  a  similar  rise  of  tem- 
perature, when,  during  two  minutes,  it  was  made  to  undergo  turgescence,  and  col- 
lapse  similar  to  that  which  takes  place  during  pulsation.  To  have  decided  this  ques- 
76 


596  ORGANIC  CHEMISTRY. 

5944.  Liebig  cites  the  following  interesting  facts.     An 
active  man  expires  13.9  ounces  of  carbon,  and  daily  con- 
sumes, in  the  same  time,  37  ounces  of  oxygen  =  51,648 
cubic  inches,  or  about  223  gallons.     Reckoning  18  inspi- 
rations per  minute,  there  must  be  25,920  consumed  per 
day,  and  consequently  fiftt  =  1.99,  or  nearly  two  cubic 
inches  of  oxygen  in  each  respiration.     In  one   minute, 
therefore,  there  are  added  to  the  blood  1.99  x  18  =  35.8 
cubic  inches  of  oxygen,  weighing  rather  less  than  twelve 
grains. 

5945.  In  one  minute,  ten  pounds  of  blood  pass  through 
the  lungs,  measuring  320  cubic  inches,  among  which  35.8 
being  divided,  there  must  be  one  cubic  inch  of  oxygen  for 
nine  of  blood  nearly.* 

5946.  Ten  Hessian  pounds  of  blood  =  76,800  grains,  if 
in  the  arterial  state,  contain  6lT5w  grains  sesquioxide  of 
iron;  if  in  the  venous  state,  55-njV  of  protoxide.t    6T4w,  the 
difference,  is  the  quantity  of  oxygen  which  the  iron  of  the 
venous  blood  can  acquire  in  the  lungs,  which,  deducted 
from  twelve  grains,  the  whole  quantity  of  oxygen  absorbed, 
leaves  5.60  grains  requiring  some  other  means  of  absorp- 
tion.    But  55ro4o  grains  of  protoxide  of  iron  would  take  up 
73  cubic  inches  of  carbonic  acid,  which  is  double  the  vo- 
lume that  the  35-dhr  of  oxygen  can  generate. 

5947.  One  glaring  defect  in  this  part  of  the  explanation, 
arises  from  the  admitted  fact,  that  nearly  one-half  of  the 
absorption  of  oxygen  is  unaccounted  for ;  5.60  in  twelve 
parts. 

OF  FERMENTATION. 

5948.  Certain  spontaneous  changes  which  ensue  in  organic  substances, 
by  which  they  are  more  or  less  decomposed  or  resolved  into  new  combina- 
tions, have  been  generically  designated  under  the  name  of  fermentation. 

5949.  For  a  long  time  only  three  kinds  of  fermentation  had  been  recog- 
nised, called,  severally,  the  vinous,  the  acetous,  and  the  putrefactive;  but 
now  we  have  several  others  added  to  the  list,  among  which  are  the  saccha- 
rine, and  the  viscous  or  lactic. 

5950.  The  production  of  cyanhydric  acid   (1323)  by  the  reaction  of 

tion,  the  author  should  have  shown  that  heat  might  be  permanently  caused  by  the 
extension  and  contraction  either  of  caoutchouc  or  the  ox  artery.     But  were  it  de- 
monstrated that  heat  could  be  thus  permanently  generated,  there  would  be  no  less 
difficulty  in  explaining  how  the  organic  substances  employed  could  thus  give  rise  to 
heat.     It  involves  the  question  of  the  materiality  of  caloric,  since,  if  material,  a  per- 
manent supply  could  not  be  derived  from  an  isolated  strip  of  caoutchouc. 
*  Stated  upon  the  authority  of  Muller.     "  Physiologic,  Vol.  1,  p.  345." 
t  Deduced  from  the  Researches  of  Denis  Richardson  and  Nasse,  Handworterbuch 
der  Physiologic,  Vol.  1,  p.  138.    Note. — Measures  and  weights  are  Hessian. 


OF  FERMENTATION.  597 

emulsine  with  amydaline  (3055),  that  of  the  oil  of  mustard  by  myrozine 
and  myronic  acid  (5091),  are,  by  Boutron  and  Fremy,  considered  as  cases 
of  fermentation;  and  to  these,  it  seems,  we  may  add  the  generation  of  ni- 
cotin,  which  is  alleged  to  be  the  effect  of  a  species  of  fermentation  promoted 
in  the  leaf  of  the  tobacco  plant  after  it  has  been  gathered. 

5951.  To  the  saccharine,  the  vinous,  acetous,  and  viscous  or  lactic  fer- 
mentation, allusion  has  already  been  made  in  treating  of  starch  (4082);  of 
cane  sugar  (4057);    of  alcohol  (5578);   of  lactin  (4070);    acetic   acid 
(5197);  lactic  acid  (5215). 

Of  the  Saccharine  and  Vinous  Fermentations. 

5952.  The  saccharine  fermentation  is  exemplified  in  the  change  which 
takes  place  in  the  mash  or  wash  of  the  distiller,  by  which  the  starch  of  the 
grain,  Cia  H10  O10,  takes  two  atoms  of  water,  2HO,  to  form  dry  grape  su- 
gar, C13  H12  O12. 

5953.  The  vinous  fermentation  ensues  in  all  cases  where  alcohol  is  pro- 
duced by  an  internal  change  in  organic  solutions.     By  some  chemists,  it  is 
supposed  that  alcohol  is  produced  only  when  grape  sugar  is  present  at  the 
outset,  or  generated  subsequently ;  since  it  is  alleged  that  cane  sugar  and 
other  saccharine  substances  must  be  converted  into  grape  sugar  before  they 
can  enter  into  the  vinous  fermentation.     It  has  been  stated,  that  by  this 
fermentation  an  atom  of  grape  sugar  is  resolved  into  the  elements  of  two 
atoms  of  alcohol  and  four  atoms  of  carbonic  acid  (5578). 

5954.  The  juice  of  the  apple,  the  pear,  or  the  grape,  at  any  temperature 
above  50°,  spontaneously  enter  into  the  alcoholic  fermentation.     This  is 
ascribed  to  the  existence,  in  them,  of  a  vegeto-animal  matter,  which  being 
first  oxidized,  afterwards  mysteriously  causes  the  sugar  to  be  resolved  into 
alcohol  and  carbonic  acid,  as  already  stated  (5578).     The  preservation  of 
fruits  and  other  organic  substances  by  heat,  in  well  closed  vessels,  is  as- 
cribed to  the  prevention  of  that  oxidizement  of  the  vegeto-animal  ferment, 
which  is  the  necessary  precursor  of  fermentation. 

5955.  In  the  case  of  wort  as  prepared  in  breweries,  there  is  great  diffi- 
culty in  inciting  a  proper  vinous  fermentation,  without  the  assistance  of 
yeast  arising  from  a  preceding  process.     Yet  during  every  well  conducted 
operation,  a  large  quantity  of  this  substance  has  to  be  thrown  off.     The 
thorough  performance  of  this  process,  called  cleansing,  has  always  been 
known  to  be  necessary  to  the  flavour  of  the  beer;  but  Liebig  alleges  that  it 
also  lessens  the  liability  to  acetification,  and  that  by  a  process  practised  in 
Bavaria,  the  yeast  being  more  thoroughly  removed  by  deposition,  such  a 
superiority  was  attained  as  respects  insusceptibility  of  sourness,  that  large 
premiums  were  offered  in  other  German  states  for  those  who  should  suc- 
ceed in  imitating  that  process.    This  consists  in  the  exposure  of  the  beer,  in 
open  shallow  vessels,  to  atmospheric  oxygen,  at  a  temperature  below  50°, 
by  which  the  vegeto-animal  matter  which  forms  the  yeast,  is  oxidized  and 
precipitated  at  a  temperature  too  low  for  that  simultaneous  conversion  of  the 
alcohol  into  acetic  acid,  which  would  be  the  consequence  of  a  higher  tem- 
perature under  like  circumstances. 

5956.  During  fermentation  there  is  a  commensurate  attenuation  of  the 
liquor,  of  which  the  extent  may  be  ascertained  by  the  hydrometer.    In  fact, 
this  instrument  and  a  thermometer  are  indispensable  to  enable  a  manufac- 
turer to  conduct  well  any  fermenting  process.     The  hydrometer  shows  that 
diminution  of  density  which  measures  the  gain  in  alcohol.     This  attenua- 


598  ORGANIC  CHEMISTRY. 

tion  is  estimated  roughly  by  the  change  in  the  froth  or  head,  which,  while 
the  presence  of  saccharine  matter  is  abundant  so  as  to  envelope  the  car- 
bonic acid,  rises  high,  but  gradually  falls  as  the  solution  becomes  thinner, 
until,  in  consequence  of  the  formation  of  the  yeast,  a  new  head  rises,  formed 
of  that  viscid  matter. 

Of  the  Acetous  Fermentation,  a  Process  of  Acetification. 

5957.  To  acidify,  signifies  to  produce  any  species  of  acidity;  but  the 
application  of  the  word  acetify  is  confined  to  those  processes  by  which  ace- 
tic acid  is  produced,  of  which  there  are  several. 

5958.  Of  the  processes  alluded  to,  that  by  which  fermented  and  spirituous 
liquids  are  made  to  generate  acetic  acid  in  the  form  of  vinegar,  has  been 
designated  as  the  acetous  fermentation  being  accompanied  by  an  apparent 
intestinal  reaction  between  the  ingredients  in  the  liquid  mixture  or  solution, 
which  undergoes  this  acetifying  process.     This  fermentation  differs  from 
the  vinous  in  requiring  an  extraneous  supply  of  atmospheric  oxygen,  by 
which,  as  has  been  mentioned,  ethyl  is  changed  into  acetyl  by  the  oxidation 
of  two  atoms  of  hydrogen,  and  the  acetyl  is  afterwards  acidified  by  the 
acquisition  of  two  more  such  atoms  (5197),  so  that,  from  a  hydrated  prot- 
oxide of  ethyl,  a  hydrated  trioxide  of  acetyl  arises. 

5959.  Yet  alcohol,  whether  strong  or  dilute,  does  not,  per  se,  undergo 
the  change  just  described.     The  presence  of  some  substance  which  may 
attract  oxygen  from  the  air,  appears  necessary  to  cause  its  acetification. 
Thus  dilute  alcohol  and  water  do  not  ferment ;  but  a  mixture  of  one  part 
of  honey  and  one  of  crude  tartar  to  thirteen  of  alcohol  and  one  hundred  of 
water,   will,  in  warm  weather,  produce  vinegar  in  a  few  weeks  (5197). 
The  change  effected  in  the  alcohol  may  be  understood  from  the  formulae 
already  given. 

5960.  The  usual  method  of  producing  vinegar  by  the  exposure  of  liquors 
in  open  vessels,  demonstrates  that  the  necessity  of  atmospheric  oxygen  had 
been  learned  in  practice.     Latterly,  the  process  has  been  greatly  expedited 
by  allowing  the  liquor  to  fall,  in  drops,  upon  the  shavings  of  beach  wood, 
the  temperature  being  kept  up  nearly  to  100°.    According  to  Liebig,  in  this 
way  one  part  of  spirit  of  wine,  containing  eighty  per  cent,  of  alcohol  with 
about  five  parts  of  water  and  Yw?rtn  °f  yeast  of  honey  or  other  ferment, 
may  be  converted  into  vinegar  in  from  twenty-four  to  thirty-six  hours. 

Of  the  Lactic  or  Viscous  Fermentation. 

5961.  This  has  only  of  late  been  treated  as  a  distinct  process,  although 
its  effects  have  long  been  known  to  those  engaged  in  the  manufacture  of 
sugar  and  fermented  liquors,  whether  for  distillation  or  drink.     The  ropi- 
ness  in  beer,  ale,  or  porter,  the  premature  acidity  of  the  distiller's  wash, 
are  referrible  to  the  process  under  consideration.     It  is  this  fermentation 
which  supervenes  in  the  absence  of  yeast,  or  whenever  any  nitrogenized 
substance,  oxidized  by  the  air  to  a  certain  extent,  is  present.     It  differs 
from  the  vinous,  in  giving  rise  to  lactic  acid,  mannite,  and  a  viscous 
matter,  usually  called  ropy,  with  hydrogen,  as  well   as  carbonic  acid. 
Many  years  since  I  was  surprised  to  find  the  gas  given  out  by  cider  in  a 
state  of  intense  fermentation,  take  fire,  and  discovered,  on  examination,  the 
inflammable  gas  to  be  hydrogen. 

5962.  Agreeably  to  a  statement  given  in  Graham,  803,  an  atom  of  man- 


OF  FERMENTATION.  599 

nite,  and  an  atom  of  lactic  acid,  are  equal  to  one  atom  of  grape  sugar, 
minus  an  atom  of  oxygen. 

5963.  I  am  under  the  impression  that  all  the  four  fermentations  may 
ensue  either  successively,  or,  to  a  certain  degree,  simultaneously.     Thus, 
either  starch  or  lactin  may  be  converted  into  grape  sugar.     This  product 
may  be  partially  changed  into  alcohol,  and  in  part  into  lactic  acid  and 
mannite  (4074);  while  a  portion  of  alcohol  simultaneously  generated,  may 
be  undergoing  acetification. 

5964.  Each  fermentation  has  its  appropriate  ferment.     Thus  diastase 
incites  the  saccharine  fermentation,  yeast  the  alcoholic,  oxidized  diastase, 
caseine  or  curd,  the  lactic;  while  the  scum  or  sediment,  called  mother  of 
vinegar,  promotes  the  acetic  fermentation.     It  is  the  obje*ct  of  the  vintner, 
the  brewer,  and  distiller,  to  permit  only  the  two  first  fermentations,  the  al- 
coholic especially,  to  which  the  saccharine  is  accessary.     This  object  is 
secured  by  taking  great  care  to  have  the  juice  or  wort  simultaneously  sub- 
jected to  a  temperature  between  60°  and  70°,  and  a  limited  exposure  to  air, 
with  the  addition  of  the  proper  ferment,  where  this  is  necessary ;  while,  by 
great  cleanliness,  the  presence  of  any  matter  capable  of  inducing  the  ace- 
tous or  lactic  fermentation  is  avoided.     Much  liquor  is  spoiled  by  the  sub- 
stitution of  the  viscous  for  the  alcoholic  fermentation. 

5965.  In  a  memoir  published  in  the  Annales  de  Chymie,  3d  series,  2d 
Vol.  257,  Messrs.  Boutron  and  Fremy  have  made  some  interesting  obser- 
vations respecting  the  generation  of  lactic  acid  in  milk.     Oxidized  caseine 
(5123)  is  considered  by  them  as  pre-eminent  in  efficacy  as  a  ferment,  for 
the  lactic  fermentation,  by  acting  on  the  sugar  of  milk  or  lactin ;  but  in 
consequence  of  an  affinity  for  the  generated  acid,  the  oxidized  caseine  forms 
with  it  an  inert  compound  which  precipitates. 

5966.  The  generation  of  lactic  acid  requires  the  presence  both  of  lactin 
and  free  oxidized  casein.     Of  course,  in  order  to  increase  the  production  of 
the  acid,  it  was  found  necessary  to  add  an  additional  quantity  of  lactin  to 
milk,  but  to  renew  the  efficiency  of  caseine,  it  was  found  sufficient  to  satu- 
rate the  lactic  acid  as  often  as  the  production  of  this  acid  was  arrested  by 
the  precipitation  of  the  oxidized  casein. 

5967.  Diastase,  after  being  exposed  a  few  days  to  the  air,  becomes  ca- 
pable of  inducing  the  viscous  or  lactic  fermentation.     The  membranes  of 
the  stomach  of  a  dog  or  calf,  or  the  substance  of  a  bladder,  by  a  like  ex- 
posure, were  found  capable  of  inciting  the  fermentation  in  question.     Yet 
animal  matters,  in  appearance  similarly  prepared,  are  productive  of  different 
results,  as  respects  the  proportions  of  mannite,  of  viscous  matter,  of  lactic 
acid,  or  alcohol,  generated.     The  means  by  which  the  various  ferments, 
respectively,  produce  their  appropriate  changes  are  involved  in  the  greatest 
obscurity.    Some  important  additions  have  been  made  to  our  knowledge,  as 
respects  the  facts.     The  ferments  have  all  been  shown  to  be  vegeto-animal 
matter  in  a  state  of  oxidizement,  and  an  analogy  seems  to  have  been  esta- 
blished between  their  influence  and  that  of  some  other  agents,  which  have 
been  considered  as  acting  by  what  has  been  called  catalysis,  which  is  a 
new  name  given  by  Berzelius  to  an  old  mystery.     It  has  long  been  known 
that  there  are  two  modes  by  which  chemical  changes  are  to  be  excited.     In 
one  of  these,  the  presentation  of  one  or  two  extraneous  elements  causes  de- 
composition and  recom position,  by  the  reactions  between  the  elements  so 
presented,  and  those  subjected  to  alteration,  as  in  the  various  cases  of  elec- 
tive affinity  (508,  &c.).     In  the  other  mode,  substances  undergo  transfor- 
mations by  being  made  to  rearrange  their  constituents  into  one  or  more  new 


600  ORGANIC  CHEMISTRY. 

combinations,  by  the  presence  of  other  bodies  with  which  they  do  not  com- 
bine, and  which,  in  some  cases,  undergo  no  change  themselves.  It  is  to 
the  last  mentioned  mode  of  reaction  that  the  name  above  mentioned  has 
been  applied.  Yet,  under  this  head,  processes  have  been  crudely  associated 
which  have  discordant  features.  Liebig  indiscriminately  gives  a  common 
explanation  to  these  processes,  and  to  those  of  fermentation,  so  far  as  they 
might  be  crudely  referrible  to  catalysis. 

5968.  The  following  processes  are  associated  by  this  distinguished  che- 
mist under  one  rationale : — the  solubility  acquired  by  platina  by  being  al- 
loyed with  silver:  the  catalyzing  influence  of  platina  sponge  or  platina 
black :  the  explosion  of  fulminating  powders  by  slight  causes :  the  reci- 
procal decomposition  of  bioxide  of  hydrogen  and  oxide  of  silver:  the 
agency  of  nitric  oxide  in  the  generation  of  sulphuric  acid :  the  action  of 
ferments. 

5969.  To  me  it  seems  that  there  is  a  great  diversity  in  the  characteris- 
tics of  the  processes  thus  alluded  to.     In  the  case  of  the  platina  alloy  there 
is  at  least  an  atom  of  silver  for  each  atom  of  platina  in  actual  combination 
with  this  metal ;  and  the  change  which  the  latter  undergoes  is  precisely  the 
same  as  that  to  which  the  former  is  subjected. 

5970.  In  the  case  of  platina  sponge  causing  the  formation  of  water,  or 
of  platina  black,  causing  the  acetification  of  alcoholic  vapour,  the  inducing 
agent  undergoes  no  change  itself;  and  it  enters  not  into  chemical  combi- 
nation either  with  the  materials,  or  the  products.     Liebig  ascribes  the  re- 
sult in  this  instance  to  the  alternate  absorption  and  subsequent  evolution  of 
oxygen  by  the  powder;  since,  after  exposure  to  the  gas,  it  may,  by  ex- 
haustion, be  made  to  give  up  a  portion.     But  the  agency  of  this  metallic 
mass  cannot  differ,  in  this  case,  from  that  in  which  it  causes  the  pure  ele- 
ments of  water  to  combine,  and  in  which,  if  absorption  take  place,  it  is  not 
confined  to  oxygen  more  than  to  hydrogen.     But  the  fact  established  by 
Faraday,  that  hydrogen  and  oxygen  may  be  made  to  unite  by  a  well  clean- 
ed plate  of  platina,  seems  irreconcilable  with  the  idea  that  absorption  is  the 
mean  of  its  accomplishment.     But  if  absorption  be  not  operative  in  one 
case,  how  can  it  operate  in  the  other? 

5971.  In  this,  as  in  all  other  cases,  Liebig  seems  to  overlook  the  all 
important  agency  of  electricity  in  the  phenomena  of  nature.     I  should 
infer,  that  the  metal  most  probably  acts  by  altering  the  electrical  po- 
larity, and  consequent  association  of  imponderable  matter.     But  having 
assumed,  that  during  the  dehydrogenation  of  alcohol  by  atmospheric  oxy- 
gen in  the  presence  of  platina  black,  this  powder  is  alternately  endowed 
with  the  power  to  take  it  from  the  air,  and  to  impart  it  to  that,  of  which 
the  attraction  for  oxygen,  under  the  circumstances,  is  too  feeble  to  take 
it  from  the  same  source,  this  distinguished  philosopher  proceeds  to  make 
the  inference  that  honey,  mother  of  vinegar,  and  other  substances  pro- 
motive  of  acetification,  act  in  the  same  way  by  absorbing  oxygen  from  the 
air,  and  abandoning  it  to  hydrogen.     But  if  agreeably  to  the  view  above 
presented,  platina  black  does  not  act  by  absorption,  no  argument,  founded 
on  the  agency  of  that  substance,  will  justify  the  idea  that  absorption  avails  in 
other  cases ;  and  it  should  be  recollected,  that  platina  black  is  very  active 
when  perfectly  free  from  moisture,  while  honey,  yeast,  mother  of  vinegar, 
and  other  substances  which  cause  acetification,  have  no  attraction  for  oxy- 
gen in  the  absence  of  water :  moreover,  that  the  necessity  for  moisture  to 
the  preparatory  oxidizement  of  gluten,  caseine,  diastase,  and  other  organic 
substances,  which  by  exposure  in  a  humid  state  acquire  their  capacity  to 


OF  FERMENTATION.  601 

act  as  ferments,  is  inexplicable.     Water  is  powerful  both  as  a  catalyzer  and 
as  a  solvent. 

5972.  Before  referring  to  the  absorption  of  oxygen  by  honey,  as  a  ground 
of  explanation  founded  on  the  analogy  of  platina  black,  the  ability  of  water 
to  cause  honey  to  absorb  oxygen  should  be  first  elucidated. 

5973.  An  electric  spark  or  any  ignited  body,  a  wire  made  incandescent 
by  a  galvanic  discharge,  has  an  influence  analogous  to  platina  sponge,  of 
which  the  minutest  particle  is  sufficient  to  cause  ignition  throughout  an  in- 
flammable mixture,  however  large.     There  is,  in  this  respect,  an  analogy 
between  the  explosion  of  inflammable  gaseous  mixtures  and  those  of  gun- 
powder, and  of  other  fulminating  powders,  of  which  some,  as  it  is  well 
known,  detonate  by  percussion  or  friction,  or  any  cause  adequate  to  derange 
the  equilibrium  of  their  particles.     In  the  cases  last  mentioned,  the  change 
produced  is  the  same,  whatever  may  be  the  exciting  cause,  and  the  mi- 
nutest portion  of  the  congeries  being  made  to  undergo  the  change,  is  of 
itself  competent  to  produce  a  like  result  as  respects  the  whole. 

5974.  The  property  which  bioxide  of  hydrogen,  and  the  oxide  of  silver, 
or  bioxide  of  lead,  have,  of  undergoing  an  explosive  deoxidizement  in  con- 
sequence of  mere  superficial  contact,  is  evidently  another  case,  since  the  re- 
action is  reciprocal.     In  the  solution  of  the  alloy  of  platina  with  silver,  one 
body  induces  another  to  undergo  the  oxidizement  to  which  it  is  itself  sub- 
jected.    In  the  case  of  the  bioxide  of  hydrogen  and  oxide  of  silver,  two 
bodies,  both  prone  to  deoxidizement,  reciprocally  induce  that  species  of 
change.     But  in  this  phenomena  there  is  no  third  body  to  perform  a  part 
analogous  to  that  of  the  nitric  acid. 

5975.  In  case  of  ferments  there  is  not  only  the  power  to  produce  a 
change,  but  also  to  produce  the  particular  changes  by  which  sugar,  alcohol, 
and  acetic  or  lactic  acid,  and  mannite,  are  respectively  generated.     More- 
over, these  bodies  are  themselves  undergoing  an  oxidation  or  decomposition 
which  is  necessary  to  their  power;  but  this  change  is  not  like  that  which 
they  induce.     Hence,  obviously,  they  operate  differently,  either  from  the 
platina  sponge,  or  platina  black,  or  from  the  silver  in  the  alloy  formed  by 
it  with  platina.     Liebig  conceives,  that  this  increased  solubility  of  platina 
by  union  with  silver,  is  at  war  with  electro-chemical  principles,  agreeably 
to  which,  any  metal  in  contact  with  another  metal,   relatively  electro- 
positive, becomes  less  susceptible  of  attack.     But  this  is  not  alleged  of 
two  metals  in  chemical  combination,  but  of  masses  in  contact,  or  having 
a  metallic  conductor  extending  from  one  to  the  other.     I  am  surprised  that 
Liebig  should  find  the  mystery  of  catalysis  lessened  by  the  solution  of  the 
alloy  alluded  to,  when  it  must  be  evident  that  if  the  oxidation  of  one  atom 
were  a  sufficient  reason  why  another  atom  combined  with  it  should  be  oxi- 
dized, an  alloy  of  gold  with  silver  ought  to  be  soluble.     Whereas,  it  is 
known  that  the  common  process  of  parting  is  founded  on  the  utter  insolu- 
bility of  gold  when  so  alloyed. 

5976.  Liebig  alleges  that  there  can  be  no  doubt  that  the  acidification  of 
alcohol  is  of  the  same  order  as  the  reaction  by  which  nitric  oxide  provokes 
the  formation  of  sulphuric  acid  in  the  leaden  chamber  (1019),  in  which 
process  the  oxygen  of  the  air  is  transferred  to  sulphurous  acid  by  the  in- 
tervention of  the  bioxide  of  nitrogen,  since,  in  like  manner  organic  sub- 
stances associated  with  spirit  of  wine,  absorb  oxygen,  and  bring  it  into  a 
particular  state  which  renders  it  liable  to  be  absorbed. 

5977.  But  in  the  case  thus  cited,  for  every  equivalent  of  acid  formed,  an 
equivalent  of  the  bioxide  combines  first  with  an  equivalent  of  oxygen,  and 


602  ORGANIC  CHEMISTRY. 

in  the  next  place  with  an  equivalent  of  the  sulphurous  acid,  forming  a  com- 
pound which  is  decomposed  by  water  into  sulphuric  acid  and  the  regenerated 
Dioxide.  There  appears  to  me  to  be  no  analogy  between  this  process  and 
that  of  the  influence  of  matter  existing  in  no  equivalent  proportion,  and 
which  cannot  be  shown  to  form  a  definite  chemical  compound,  either  with 
acetyl  or  hydrogen.  It  is  not  represented  that,  in  the  vinous  fermentation, 
any  union,  either  transient  or  permanent,  takes  place  between  the  elements 
of  the  sugar  and  those  of  the  ferment :  on  the  contrary  it  is  alleged,  that 
the  oxidation  and  precipitation  of  the  yeast  proceeds,  pari  passu,  with  the 
alcoholification. 

5978.  As  to  all  the  processes  referred  to  for  illustration,  as  well  as  those 
of  fermentation,  which  they  are  alleged  to  resemble,  it  appears  to  me  that 
Liebig  and  his  disciples  have  been  too  sanguine  of  their  capacity  to  give 
adequate  elucidation. 

5979.  Respecting  changes  of  the  kind  above  described  as  catalytic,  Dr. 
Kane  uses  the  following  language: — "The  elements  of  a  compound  are  re- 
tained together  in  certain  molecular  arrangement,  because  the  affinities 
are  there  satisfied;  but  it  is  natural  to  suppose  that  whilst  the  elements 
remain  the  same,  their  affinities  for  each  other  might  be  just  as  completely 
satisfied  by  a  different  molecular  arrangement."     This  language  might  be 
held  more  reasonably,  were  this  variation  in  arrangement  accompanied  by 
no  concomitant  acquisition  of  chemical  properties;  but  is  it  reasonable  to 
consider  the  difference  between  sugar,  and  the  alcohol  and  carbonic  acid 
into  which  it  is  resolvable,  as  arising  merely  from  molecular  arrangement? 
Can  the  active  influence  of  alcohol  upon  the  animal  nerves  be  due  merely 
to  the  situations  respectively  occupied  by  its  three  ultimate  ponderable  ele- 
ments, carbon,  hydrogen,  and  oxygen,  of  which  it  consists?    Admitting  that 
the  union  of  oxygen  with  the  ingredients  of  gluten  could,  by  imparting  any 
consequent  mechanical  impulses,  cause  the  hydrogen  and  oxygen  of  an 
atom  of  water  to  unite  with  the  elements  of  sugar,  and  to  separate  into  alco- 
hol and  carbonic  acid  as  above  mentioned,  how  can  that  movement,  or  the 
consequent  rearrangement  of  the  ponderable  particles,  explain  the  acqui- 
sition of  new  properties,  of  which  the  combining  atoms,  or  the  compounds 
previously  containing  them,  were  destitute?    That  the  presence  of  yeast  in- 
duces the  fermentation  of  alcohol,  and  that  diastase  determines  the  genera- 
tion of  sugar,  is  admitted;  but  I  am  surprised  that  any  philosopher  should 
conceive,  that  without  first  ascertaining  upon  what  the  difference  of  the  pro- 
perties of  alcohol  and  sugar  is  dependent,  we  can  understand  how  that  dif- 
ference is  caused.     Liebig  infers  that  a  body  in  the  act  of  decomposition  or 
combination,  may  communicate  a  movement  to  the  atoms  of  an  adjoining 
compound,  so  that  gluten  in  the  state  of  oxidation,  in  which  it  is  called 
yeast,  induces  sugar,  C13  H11  O11,  existing  in  the  same  liquid,  to  unite  with 
the  elements  of  water,  making  C13  K13  O13,  separating  into  four  equivalents 
of  carbonic  acid  and  two  of  alcohol. 

5980.  Adopting  the  same  views  as  Liebig,  Dr.  Kane  alleges  "  that  the 
slow  decomposition  of  diastase  communicates  to  the  molecules  of  many 
thousand  times  its  weight  of  starch,  the  degree  of  motion  necessary  for 
their  rearrangement,  and  the  appropriation  of  the  elements  of  water  requi- 
site for  the  formation  of  starch  sugar." 

5981.  It  is  perfectly  evident,  that  the  particles  of  the  catalyzed  substance 
are  in  some  way  so  affected  by  the  catalyzing  body  as  to  be  put  into  a  state 
of  reaction,  which  had  not  otherwise  ensued ;  but  that  this  is  accomplished 
merely  by  imparted  motion  appears  to  me  to  be  a  surmise  destitute  of  plau- 


OF  FERMENTATION.  603 

sibility.  The  fact  that  the  weight  of  the  diastase  requisite  to  saccharify 
starch  is  so  very  small,  as  is  alleged  by  Dr.  Kane,  evidently  renders  it  ex- 
tremely improbable  that  it  acts  by  creating  any  mechanical  disturbance. 
Yet  this  respectable  chemist  is  so  completely  carried  away  by  this  idea, 
that  he  proceeds  to  make  the  following  remark:  "  This  law,  of  which  the 
simplest  expression  is  that  where  two  chemical  substances  are  in  contact, 
any  motion  occurring  among  the  particles  of  the  one  may  be  communicated 
to  the  other,  is  of  a  more  purely  mechanical  nature  than  any  other  princi- 
ple yet  received  in  chemistry;  and  when  more  definitely  established  by 
succeeding  researches,  may  be  the  basis  of  a  dynamic  theory  in  chemistry, 
as  the  law  of  equivalents  and  multiple  combination  expresses  the  statical 
condition  of  bodies  which  unite  by  chemical  force  " 

5982.  I  perfectly  agree  in  opinion  with  the  author  of  these  suggestions, 
as  to  the  purity  of  the  mechanical  attributes  of  the  principle  on  which  they 
are  founded,  but  cannot  on  this  very  account  deem  them  competent  to  ex- 
plain the  phenomena  on  which  he  conceives  them  to  bear. 

5983.  As  the  mechanical  influence  of  the  motion  of  bodies  is  as  the 
weight  multiplied  by  the  velocity,  is  it  conceivable  that  any  movement  in 
the  particles  of  one  part,  by  weight,  of  diastase,  can  be  productive  of  ana- 
logous movements  in  two  thousand  parts  of  starch  ? 

5984.  The  idea  that  yeast  might  owe  its  power  to  animalcules,  suggested 
itself  to  me  more  than  thirty  years  ago,  and  seems  to  have  some  support 
from  the  fact,  that  fermentation  only  thrives  within  the  range  of  tempera- 
ture compatible  with  animal  life.     Latterly,  its  activity  has  been  ascribed 
to  the  power  of  extremely  minute  vegetables.     Kane,  while  admitting  the 
existence  in  yeast  of  a  vast  number  of  globular  bodies,  possibly  animal- 
cules, treats  the  idea  as  untenable,  because  the  weight  of  the  alcohol  and 
carbonic  acid  is  greater  than  that  of  the  sugar  employed.     But  if  the 
union  of  water  with  the  elements  of  the  sugar,  can  add  to  the  weight  of  the 
products,  without  the  assistance  of  animalcules,  wherefore  should  their 
agency  be  inconsistent  with  an  augmentation  from  the  same  source?     But 
the  weight  of  the  alcohol  and  carbonic  acid  are  just  equal  to  that  of  the 
sugar,  if  this  be  assumed  to  be  in  the  state  of  sugar  of  grapes  (5578). 

5985.  Independently  of  any  agency  of  this  kind,  which  seems  even 
more  probable  in  the  case  of  some  species  of  infection,  than  in  that  of  fer- 
mentation, I  conceive  that  the  present  state  of  our  knowledge  does  not  allow 
of  our  comprehending  the  means  by  which  bodies,  whether  organic  or  inor- 
ganic, are  endowed  with  the  powers  ascribed  to  catalysis ;  but  that  we  have 
great  reason  to  believe  that  these  powers,  as  well  as  all  the  properties  which 
ultimate  elements  acquire  by  diversity  of  association,  as  in  compound  radi- 
cals, are  due  to  the  same  source  as  the  phenomena  of  galvanic  and  statical 
electricity. 

5986.  It  is  well  known,  that  although  pure  zinc  is  not  susceptible  of  oxi- 
dation by  exposure  to  dilute  sulphuric  acid,  yet  that,  when  containing  mi- 
nute proportions  of  other  metals,  as  in  the  case  of  commercial  zinc,  it  be- 
comes liable  to  rapid  oxidation  by  the  same  reagent.     This  Faraday  ex- 
plained by  the  electro-chemical  influence  of  the  comparatively  electro-nega- 
tive metallic  particles  distributed  throughout  the  mass  of  the  zinc,  which  he 
conceived  to  be  productive  of  as  many  local  galvanic  circuits  with  corres- 
ponding currents.     This  explanation  has,  I  believe,  been  universally  sanc- 
tioned, and  was  consistent  with  the  previous  discovery  of  Sturgeon,  that 
when,  by  amalgamating  the  surface  with  mercury,  a  metallic  communica- 

77 


604  ORGANIC  CHEMISTRY. 

tion  was  made  between  the  electro-positive  and  electro-negative  metallic 
particles,  so  as  to  prevent  the  formation  of  electrolytic  currents  through  the 
oxidizing  liquid,  the  zinc  became  nearly  as  insusceptible  of  union  with  oxy- 
gen, as  when  in  a  pure  state. 

5987.  Nevertheless,  either  when  pure,  or  when  amalgamated,  the  zinc 
was  found  oxidizable  by  diluted  sulphuric  acid,  provided  it  were  made  the 
element  of  a  galvanic  pair. 

5988.  The  facts  above  mentioned  having  been  recalled  to  the  attention 
of  the  scientific  reader,  I  beg  leave  to  inquire  whether  the  influence  thus  as- 
cribed by  Faraday  to  the  electro-negative  metallic  particles  has  not  a  greater 
analogy  with  that  of  a  ferment,  than  those  which  have  been  brought  for- 
ward by  Liebig,  Kane,  and  others,  with  a  view  to  explain  the  influence  of 
that  class  of  agents  upon  mechanical  and  chemical  principles'?     Wherefore 
may  not  the  distribution  of  nitrogenated  substances  throughout  a  mass  of 
inorganic  matter,  operate  as  do  the  metallic  impurities  in  commercial  zinc? 
The  existence  of  a  powerful  voltaic  series  in  the  gymnotus  and  other  elec- 
trical fishes,  shows  that  the  substances  which  enter  into  the  composition  of 
animal  matter  are,  when  duly  associated,  as  capable  as  metals  of  forming 
the  elements  not  only  of  simple,  but  of  complex  galvanic  circuits. 


OF  THE  PUTREFACTIVE  FERMENTATION. 

5989.  To  that  species  of  spontaneous  decomposition  which  is  called  pu- 
trefactive, animal  substances,  in  general,  are  much  more  disposed  than  ve- 
getable; and  the  effluvia  which  they  emit,  during  the  change,  are  much 
more  offensive.     It  seems  as  if  certain  affinities  which  exist  between  the 
ultimate  elements  of  many  vegetable  and  animal  substances,  although  sus- 
pended by  the  inexplicable  powers  of  vitality,  resume  their  operation  as  soon 
as  those  powers  cease,  with  greater  or  less  activity,  according  to  the  nature 
of  the  substance,  and  the  influence  of  heat  and  moisture. 

5990.  The  presence  of  phosphorus  and  sulphur  contributes  greatly  to  the 
fetor  of  animal  putrefaction.    On  the  other  hand,  few  animal  substances  are 
susceptible  of  the  vinous  or  acetous  fermentation. 

5991.  Liebig  seems  disposed  to  obliterate  the  line  which  was  heretofore 
drawn  between  fermentation  proper,  and  putrefaction.     He  alleges,  that  in 
practice  the  principal  mean  of  discrimination  has  been  the  diversity  of 
odour.     To  fermentation  has  been  ascribed  all  processes  attended  by  trans- 
formations, resulting  from  internal  reaction,  which  are  attended  by  no  un- 
pleasant smell ;  whereas  fetid  processes,  in  other  respects  analogous,  have 
been  designated  as  putrefactive :  but  that,  in  point  of  fact,  the  presence  of 
nitrogen  seems  to  have  been  the  usual  associate  of  substances  prone  to  what 
is  called  putrefaction. 

5992.  But  so  far  as  fetidity  is  an  essential  attribute  of  putrefaction,  the 
presence  of  hydrogen,  with  sulphur  and  phosphorus,  seems  to  me  more  es- 
sential than  that  of  nitrogen,  since  this  element  is  much  more  rarely  the 
vehicle  of  fetid  emanations,  and,  when  isolated,  is  remarkably  inodorous. 

5993.  The  presence  of  water,  or  of  its  elements,  seems  indispensable  to 
the  spontaneous  decomposition  of  organic  substances.     In  no  instance  is 
either  the  vinous,  acetous,  or  putrefactive  fermentation  induced,  in  sub- 
stances which  are  perfectly  dry.     The  effect  of  desiccation  in  preserving 
meat  and  fruits,  sufficiently  proves  the  correctness  of  this  allegation.     It  is, 
probably,  by  paralyzing  the  activity  of  the  water  in  meat,  that  salt  favours 


OF  THE  PUTREFACTIVE  FERMENTATION.  605 

its  preservation ;  and  the  beneficial  influence  of  sugar  upon  preserves  may 
in  like  manner  be  explained. 

5994.  The  peculiar  efficacy  of  water  in  promoting  fermentation,  of  \vl  at- 
ever  kind  it  may  be,  rests,  as  I  conceive,  on  the  same  basis  as  its  peculiar 
efficiency  in  promoting  electrolysis.     And  until  we  are  capable  of  compie- 
hending  the  part  it  performs  in  the  one  case,  we  shall  vainly  endeavour  to 
understand  the  duty  which  it  fulfils  in  the  other. 

5995.  When,  in  addition  to  water,  nitrogen  is  a  constituent,  the  tendency 
to  decomposition  is  increased.     Gluten  and  yeast,  which  contain  nitrogen, 
are  very  liable  to  an  extremely  offensive  putrefaction.     To  their  deficiency 
in  this  principle,  Dr.  Turner  ascribes  the  indisposition  of  oils  to  putrescency ; 
but  I  conceive  their  freedom  from  water,  and  incapacity  to  unite  with  it,  to 
be  the  true  cause. 

5996.  The  insusceptibility  of  the  vegetable  alkalies  to  decomposition, 
while  containing  both  hydrogen,  oxygen,  and  nitrogen,  may  arise  partly 
from  their  sparing  solubility  in  water,  and  partly  from  the  predominance  of 
carbon  in  their  composition  (5506). 

5997.  Although  heat,  to  a  certain  extent,  is  necessary  to  putrefaction,  it 
may  be  arrested  by  a  high  temperature,  as  well  as  by  frost.     In  the  one 
case,  water,  being  vaporized,  is  removed ;  in  the  other,  being  congealed,  be- 
comes inert. 

5998.  Thenard  alleges  that  water  is  not  decomposed  during  putrefaction, 
but,  on  the  contrary,  generated. 

5999.  Besides  water,  we  may  enumerate  ammonia,  with  carbonic,  acetic, 
and  sulphydric  acid,  also  carburetted  and  in  some  cases  phosphuretted  hy- 
drogen, among  the  products  of  putrefaction. 


INDEX 


THAT  PORTION   OF   THIS    COMPENDIUM 


WHICH  RELATES  TO 


INORGANIC  CHEMISTRY. 


Absorption  of  aeriform  fluids,  222— by 
charcoal,  223— of  heat,  6— of  light,  79 
— of  nitric  oxide,  183 — produces  heat, 
6,  223— by  silk  and  woollen  stuffs,  223. 

Acetate  of  ammonia,  5 — of  baryta,  276 — 
of  copper,  314— of  lead,  90,  318— of 
zinc,  332. 

Acetates  in  general,  459.* 

Acid,  acetic,  314,  318* — alumina  acts  as 
an,  268 — antimonic,  346 — antimonious, 
346— arsenic,  335,  336*— arsenious,  91, 
335,  336— auric,  trioxide  of  gold,  291 
— benzoic,  329 — boric,  250 — bromic,  129 
—carbonic,  225,  229— chloriodic,  133— 
chloric,  126 — chlorohydric,  141,  157, 
162,  163 — strength  of,  164— chlorous, 
123,  124,  125— chloroplatinic,  294— 
chloroplatinous,294 — chloroxycarbonic, 
233* — chloroplatinic  and  chloroplati- 
nous,282 — chromic,  353 — croconic,232* 
— cyanhydric,  153,  246,  278,  367*— cy- 
anic, 243* — cyanoferric,  243— cyanofer- 
rous,  243, 246— cyanuric,  243*— denned, 
357 — dephlogisticated  marine  (i.  e.  chlo- 
rine), 117 — fluoboric,  258 — fluohydric, 
134,  256— fluosilicic,  134,  251,  257— 
fluohydroboric,  257 — fluohydrosilicic, 
257— fulminic,  243*— hydrochloric,  160, 
162,  163,  285— hydrofluoric,  256— hy- 
drous cyanic,  244 — hyperiodic,  133 — 
hypochlorous,  123,  362 — hyponitrous, 
183 — hyposulphuric,  1 37 — hy  posulphu. 
rous,  137 — iodic,  131,  133 — iodohydric, 
131,  159,  165 — iodous,  133— manganic, 
354— margaric,  202*— mellitic,  232— 
muriatic  or  chlorohydric,  160 — nitric, 
190,  191 — nitro-muriatic  (aqua  regia,) 
291,292 — nitrous,  184— nitrosonitric,213 
— oxalic,  231* — oxy,  or  per,  manganic, 
354 — oxymuriatic,119t — perchloric,  127 
— phosphoric,  216 — phosphorous,  216 — 

*  See  Index  to  Organic  Chemistry. 

t  See  Emendation,  end  of  Index,  page  xix- 


prussic  (cyanhydric),  246,  248*— selen- 
hydric,  171— selenic,  141,  142— sele- 
nious,  141,  142 — silicic,  253 — stearic, 
202— succinic,  329— sulphydric,  166, 
168* — sulphocarbonic,  234 — sulphocy- 
anhydric,  245— sulphuric,  139,  140 — 
sulphurous,  137 — tartaric,  346* — tellu- 
hydric,  171 — tungstic,  355. 

Acidifiable  metals,  261. 

Acidity,  201. 

Acids,  amphydric,  304— halohydric,  159, 
304 — organic,  109* — relation  to  positive 
pole,  109 — with  mercury,  304 — reaction 
of,  with  litmus,  203. 

Action,  mechanical,  of  the  lungs,  29. 

Aeriform  or  elastic  fluids,  105. 

Aerolites,  324. 

Affinity,  simple  and  double  elective,  or 
complex,  89,  90. 

Agency  of  water,  151.* 

Aggregation,  attraction  of,  83. 

Air,  11,  18, 19,  22,  23,  24,  28, 41, 103, 154, 
174 — cold  and  cloudiness  consequent 
to  rarefaction  of,  37— condensation  of, 
27— elastic  reaction  of,  22— pump,  21, 24 
—rarefaction  of,  23— weight  of,  14. 104. 

Alcohol,  101,  239.* 

Alloys,  263. 

Alkalies,  fixed,  278,  288— organic,  109.* 

Alkanet,  as  a  test  for  alkalies,  203.t 

Alkaline  earths,  270,  271. 

Alum,  264,  266. 

Alumina,  267— hydrate  of,  266,  267. 

Aluminate  of  magnesia,  of  zinc,  265. 

Aluminium,  268. 

Amalgams,  301. 

Amalgam  of  ammonium,  209. t 

Amalgam  of  gold,  290 — of  potassium,  so- 
dium, 208,  209. 

Amalgams  of  calcium,  barium,  strontium 
272.  t 

*  See  Index  to  Organic  Chemistry. 
t  See  Index  to  Electricity. 


11 


INDEX. 


Amethyst,  265. 

Ammonia,  90,  92,  205,  206,  207*— reac- 
tion with  oxide  of  silver,  or  that  of  cop- 
per, 90— nitrate  of,  180. 

Ammoriiacal  nitrate  of  copper,  91 — of  sil- 
ver, 91. 

Ammonium,  208 — chloride  of,  209 — reac- 
tion of  chloride  with  lime,  92. 

Amphigen  bodies,  108. 

Analysis  of  gaseous  mixtures,  eudiometer 
for,  185,  228 — volumescope,  Volta's  eu- 
diometer for,  148— of  olefiant  gas,  238. 

Animal  charcoal,  222*— respiration,  227* 
— substances,  370.* 

Anhydrous  antimonic  acid,  346 — sulphu- 
ric acid,  139.* 

Annealing,  254,  255,  263. 

Anode,  197.  t 

Anthracite,  220. 

Antimony,  89,  344— bichloride  of,  347— 
bisulphide  of,  349— crocus  of,  348— 
glass  of,  348 — golden  sulphur  of,  348 — 
liver  of,  348 — oxysulphide  and  hydrated 
oxysulphide  of  (kermes  mineral),  348 — 
precipitated  sulphide,  348 — perchloride 
of,  347— regulus  of,  344— selenide  of, 
349 — sesquichloride,  347 — sesquioxide, 
345,  347,  349— sesquisulphide,  347,  348 
— sulphide,  348. 

Aqua  ammonite,  208. 

Aqua  marina,  269. 

Aqua  regia,  291. 

Aqueous  vapour,  31  to  41 ;  151  to  155. 

Arbor  Dianse,  SO — Saturni,  86. 

Argand  lamp,  65. 

Argentine  flowers  of  antimony,  345. 

Aridity  of  the  air,  155. 

Arsenic,  334 — compounds  of,  338* — means 
of  detecting,  340 — poisoning  by,  340 — 
selenides  of,  339— sulphides  of,  338— 
reactions  of,  338,  339. 

Arseniates  and  arsenites,  337. 

Assay  furnace,  299. 

Athermane  and  diathermane  bodies,  56. 

Atmosphere,  19, 174;  see^r — eudiometer 
for  analysis  of,  214. 

Atomic  theory,  weights,  95,  96,  97. 

Attraction,  2,  83,  88. 

Attrition,  ignition  by,  61. 

Aurate  of  ammonia,  291. 

Avena  sensitiva,  hygrometer  by,  39. 

Azote  (nitrogen),  172.* 

Barium,  271,  272,  276 — process  for  evolu- 
tion of,  272.  t 

Barometer  and  barometric  column,  expla- 
nation of,  14  to  26. 

Barometer  gauge,  26. 

Baryta,  or  barytes,  275,  276. 

Basacigen  elements,  108,  261. 

Basidity,  109. 

Basifiable  metals,  261. 

Base  metals,  260. 

Bellows,  of  and  forge  fires,  65. 

Benzoic  acid,  329. 

Benzoate  of  lead,  317. 

*  See  Index  to  Organic  Chemistry, 
t  See  Index  to  Electricity. 


Berzelius.    See  letter  from. 

Biborate  of  soda,  249,  367. 

Bibromide  of  mercury,  307. 

Bicarburet  of  hydrogen,  235,  240. 

Bicarburet  of  nitrogen  or  cyanogen,  241.* 

Bichloride  of  antimony,  345. 

Bichlorine  ether,  or  chlorohydrate  of  chlo- 
ride of  acetyl,  233,  241* 

Bichloride  of  mercury,  301,  306. 

Bichromate  of  lead,  317. 

Bicyanide  of  mercury,  241,  246,  308. 

Bihydroguret  of  carbon  (fire  damp),  236. 

Biiodide  of  lead,  319. 

Biiodide  of  mercury,  307. 

Binary  salts,  358. 

Bioxalate  of  potash,  231. 

Bioxide  of  lead,  316. 

Bioxide  of  manganese,  354. 

Bioxide,  136. 

Bioxide  of  barium,  276. 

Bioxide  of  calcium,  275. 

Bioxide  of  hydrogen,  156 — of  mercury. 
301— of  tin,  320. 

Biphosphates,  367. 

Bismuth,  322,  323. 

Bisulphide  of  antimony,  345 — of  bismuth, 
324— of  carbon,  234— of  iron,  325— of 
mercury,  301. 

Bitartrate  of  potash,  281,  369. 

Bitter  almonds,  oil  of.* 

Bitumen,  220. 

Bituminous  coal,  220. 

Black  oxide  of  copper,  312 — of  iron,  325 — 
of  manganese,  354 — of  mercury,  302. 

Bleaching,  119,361. 

Bleaching  salt,  172,  361. 

Blende,  331. 

Blowpipe,  65. 

Blowpipe,  compound,  or  hydro-oxygen, 
66. 

Blue  stone,  or  blue  vitriol  (sulphate  of 
copper),  313. 

Boiling  point,  31  to  37,  52. 

Bone,  or  ivory  black,  221. 

Borates,  367. 

Borax,  367. 

Boron,  249,  250. 

Boruretted  hydrogen,  284. 

Boruret  of  potassium,  284. 

Brass,  89,  263. 

Brazil  wood,  test  for  alkalinity,  203. 

Bromide  of  carbon,  233 — of  cyanogen,  245 
— of  iodine,  133 — of  mercury,  304 — of 
selenium,  142 — of  silver,  299 — of  sul- 
phur, 140. 

Bromine,  128 — in  mineral  springs,  129. 

Bronze,  89. 

Cadmium,  352. 

Calamine  (silicate  or  carbonate  of  zinc), 
331. 

Calcia,  or  lime,  273— alkalinity  of,  203. 

Calcination,  274. 

Calcium,  272,  300— apparatus  for  evolu- 
tion of,  272. 

Caloric,  3,  5, 14,  74,  263. 

Calomel,  304. 

*  See  Index  to  Organic  Chemistry. 


INDEX, 


111 


Calori  motor.! 

Cannel  coal,  221).* 

Caoutchouc,  239.* 

Carbohydrogen,  235,  240,  241.* 

Carbon,  220. 

Carbonates,  367. 

Carbonate  of  cadmium,  352 — of  lead,  277, 
317,  318 — of  lime,  274 — of  magnesia, 
271— of  zinc,  331. 

Carbonic  acid,  liquid,  solid,  225,  226,  229, 
230. 

Carbonic  oxide,  224.t 

Carburets  of  potassium,  283. 

Cast  steel,  325. 

Cathode,  197.t 

Cementation  of  iron,  325. 

Cerium,  262. 

Ceruse,  277,  319. 

Chalybeate  springs,  326. 

Chameleon  mineral,  354. 

Charcoal,  220,  221,223. 

Chemical  affinity,  83, 88— attraction,  83— 
equivalents,  94 — implement,  21 — reac- 
tion, 2. 

Chemical  symbols,  96. 

Chemistry,  definition  of,  1. 

Chloracid,  268. t 

Chloral,  232.t 

Chlorate,  362. 

Chlorate  of  potash,  361.  363. 

Chloride,  122,  285. 

Chloride  of  aluminum,  268 — ammonium, 
209— boron,  251— bromine,  130— of  glu- 
cinium, yttrium,  thorium,  285— gold, 
292— hydrogen,  160— iodine,  133 — iron, 
329— mercury.  304— of  lithium,  deli- 
quescence,  solubility  of,  in  alcohol,  284 
— of  nitrogen,  128 — phosphorus.  121, 
217 — potassium,  127 — selenium,  142 — 
silicon,  254 — silver,  299 — sulphur,  140 
—thorium,  270,  285— yttrium,  285. 

Chlorides  of  carbon,  233— of  sulphur,  140. 

Chlorine,  108,  117, 119, 157, 241— hydrate 
of,  156. 

Chlorite  or  hypochlorite  of  lime,  172. 

Chlorobases,  200. 

Chlorohydrate  of  the  chlorobase  of  cop- 
per, 314. 

Chlorosalts,  370. 

Chlorohydrates,  285. 

Chromates,  319. 

Chromium,  350. 

Cinnabar,  300. 

Cisterns,  hydropneumatic,  105,  106. 

Classes  of  metals,  260. 

Classification,  108,  109,  110, 198.  See  let- 
ter on  Berzelian  nomenclature.  &>c. 

Clay,  266. 

Cobalt,  251,  354. 

Cohesion,  83,  91. 

Coke,  220. 

Cold,  27, 62,  68,  73— by  combination,  73— 
by  vaporization,  60— radiation  of,  50,  55. 

Colouring  matter  of  the  blood,  245.* 

Colours,  different  rays,  78,  79. 

Columbium,  354. 

*  See  Index  to  Organic  Chemistry, 
f  See  Index  tn  Electricity. 


Cork,  239 — to  ascertain  specific  gravity 
of,  100. 

Combustibles,  foundation  of  idea  of,  198. 

Combination,  Cl,  91. 

Combustion,  113,  118,  136,  194,  251,  310. 

Complex  or  double  elective  affinity,  90. 

Compound,  or  hydro-oxygen,  blowpipe, 
66. 

Concave  mirrors,  53. 

Condensation,  27  to  30. 

Condensation  of  gases  by  charcoal,  222 — 
for  illumination,  240. 

Condenser,  27. 

Congelation  of  water,  67  to  73— of  car- 
bonic acid,  229 — of  prussic  acid,  248 — 
of  sulphur,  bismuth,  antimony,  zinc,  86. 

Copper,  310,  311,312. 

Corindon  Telesie,  265. 

Corrosive  sublimate,  305. 

Croconate  of  potash,  232. 

Crocus  of  antimony,  348. 

Cryophorus,  71,  72. 

Crystallization,  83,  84. 

Crystallized  potash,  282. 

Crystallography,  84. 

Crystals  of  Venus,  314. 

Cubic  galena,  141. 

Cuprum  ammoniatum,  313. 

Cupel  and  cupellation,  297. 

Culinary  paradox,  32. 

Cyanates,  368. 

Cyanide,  or  bicyanide,  of  mercury,  241, 

Cyanide,  cyanure,  or  cyanuret,  of  potas- 
sium, 370 — silver.  299 — zinc,  333 — iron, 
242. 

Cyanobases,  200. 

Cyanoferrate  of  potassium,  243. 

Cyanoferrite  qf  potassium,  243,  247. 

Cyanogen,  108,  157,  241,  242. 

Cyano  salts,  370. 

Cyanures,  cyanurets,  or  cyanides,  287,370. 

Dalton  on  vapour,  40. 

Damask  steel,  325. 

Daniell's  blow-pipe,  erroneously  so  called, 

67. 

Decayed  wood,  light  from,  76. 
Decoloration  by  charcoal,  222 — by  proto- 

chloride  of  tin,  322. 
Decomposition  of  ammonia, 207 — of  water, 

152. 

Decrystallization,  87. 
Definite  proportions,  83,  93. 
Dephlogisticaled  marine  acid,  (chlorine,) 

117. 
Derbyshire  spar,  (chloride  calcium,)  251, 

256. 
Desiccation   of  air,  means   of  effecting, 

70— of  the  skin,  154. 
Detection  of  arsenic,  340. 
Deuto  carbohydrogen,  235,  237. 
Deutoxidcs  defined,  136. 
Deutoxide  of  hydrogen,  156. 
Diacetate  of  lead,  318. 
Diamond,  220. 
Diaspore,  266. 

*  See  Index  to  Organic  Chemistry. 


IV 


INDEX, 


Diathermane,  and  athermane,  bodies,  56 
Dicarburet  of  hydrogen,  236. 
Dichloride  of  carbon,  233. 
Bichloride  of  copper,  314. 
Dioxide,  disulphide  of  lead,  319. 
Differential  thermometer,  13. 
Dilatation  by  heat,  9. 
Dioxide  defined,  136. 
Dioxide  of  lead,  316. 
Disinfecting  power  of  charcoal,  222. 
Disinfection  by  hypochlorites,  361,  362. 
Dispersion  of  light,  78. 
Disulphide  of  copper,  311,  315. 
Dolomite,  271. 

Double  elective,  or  complex  affinity,  90. 
Double  oxysalts,  368. 
Double  salts  of  metals,  261. 
Double  silicates,  368. 
Drummond's  lime  light,  so  called,  67. 
Dutch  gold  leaf,  combustion  of,  in  chlo- 
rine, 119. 

Ductility  of  metals,  263. 
Dyeing,  267 — mordants  for,  267.* 
Dynamic  electricity,  82. t 

Earths,  264. 

Ebullition,  32— by  cold,  32. 

Effervescence,  43. 

Elasticity,  15  to  44. 

Elasticity  of  metals,  263. 

Electricity,  see  separate  treatise  on. 

Electro  magnetism.t 

Electrometer  and  electroscope,  t 

Electro-negative  metals,  261. t 

Electrophorus,  58.t 

Electro- positive  metals,  261. t 

Emerald,  269. 

Epsom  salts,  89,  271,356. 

Equivalents,  94. 

Essential  oils,  241.* 

Ether,  209.* 

Ether,  chloric,  perchloric,  explosive,  128.* 

Etherine,  236  * 

Euchlorine,  124,  361. 

Ethiop's  mineral,  300 — Euclase,  269. 

Eudiometer,  185,  238— of  Volta,  148— sli- 
ding rod,  175, 176,  185. 

Eudiometry,  148,  184,  213. 

Evaporation,  40,  41 — by  air,  41 — cold  pro- 
duced by,  41,  68  to  73. 

Everitt's  process  for  cyanhydric  acid,  247. 

Evolution  of  iodine, 

Exception  to  the  law  that  chemical  reac- 
tion requires  fluidity,  92. 

Exceptions  to  the  law  that  liquids  expand 
by  heat,  9. 

Exhaustion,  43. 

Expansion  of  fluids,  10,30 — liquids,  8 — so- 
lids, 6 — supposed  exception  to  the,  7 — 
theory  of,  31— water,  9. 

Explosive  power  of  steam,  37. 

Extreme  pressure,  vaporization  of  liquids 
under,  37. 

Explosion  of  fulminating  mercury,  5 — by 
high  steam,  37 — mechanical  action  in- 
ducing decomposition,  62 — of  chlorous 

*  See  Index  to  Organic  Chemistry, 
t  See  Index  to  Electricity. 


acid,  euchlorine,  126 — oxychlorate  of 
ethyl,  128* — chlorine  with  hydrogen, 
160 — hydrogen  with  oxygen,  148 — ok- 
fiant  gas  with  oxygen,  239. 

False  copper.  Kupfer  nickel,  351. 

Feldspar,  268,  357. 

Ferri  et  potassae  tart,  368. 

Ferroprussiate,  or  cyanate  of  potash,  cy- 
anoferrite  of  potassium,  242. 

Ferruginous  minerals,  324. 

Fffitid  or  feculent  emanations  neutralized, 
224,  360. 

Filters  of  charcoal,  &c.,  222. 

Finery,  cinder,  328. 

Fire  damp,  235. 

Flame,  162 — of  hydrogen,  146 — reddened 
by  strontia,  277. 

Flowers  of  sulphur,  135 — antimony,  345 — 
zinc,  331. 

Fluids,  ae'riform,  10,  14  to  44,  105.  See 
Gases. 

Fluoride  of  arsenic,  338 — bismuth,  324 — 
calcium,  212,  256— chromium,  353— bo- 
ron, 134,  255— silicon,  255— lead,  319— 
mercury,  308— silver,  299— zinc,  333, 

Fluorides,  370.t 

Fluosalts,  370.t 

Fluoborate  of  hydrogen,  258.t 

Fluocolumbate  of  potassium,  354. 

Fluohydrate  of  potassium,  258.t 

Fluoglucinate  of  potassium,  269. 

Fluorine,  108,  134,  157,  252. 

Fluorine  acids,  or  fluacids,  157. 

Fluosilicate  of  hydrogen,  370.t 

Fluothorate  of  potassium,  270. 

Flux,  black,  white,  crude,  322* 

Forge  fires,  65. 

Fossil  coal,  220.* 

Fowler's  solution,  337. 

Freezing  of  mercury,  71,  230 — mixtures, 
73,  230— water,  68,  73. 

French  alum,  266. 

Friction,  ignition  by,  60. 

Frigorific  mixtures,  73. 

Fulminates,  368. 

Fulminating  gold,  206— mercury,  303— 
silver,  206. 

Fulminate  of  mercury,  368. 

Fusible  carburet  of  iron,  (cast  iron,)  325. 

Fusion  of  platina,  68. 

Gadolinite,  269. 

Gahnite,  265. 

Galena,  141,  315. 

Galena  argentiferous,  297. 

Galvanism.! 

Gases,  table  of  specific  gravities  of,  104 — 
of  equivalent  weights  and  volumes,  189. 

Gaseous  ammonia,  205 — chlorohydric  acid, 
162— sulphydric  acid,  166— sulphuric 
acid,  139. 

Gaseous  mixtures,  eudiometrical  analysis 
of,  148,  175,  185,  224— influence  of  pla- 
tina on,  296. 


*  See  Index  to  Organic  Chemistry. 

f  See  Essays  and  Letters  on  Nomenclature. 

J  See  Index  to  Electricity. 


INDEX, 


Gas  lighting,  239. 

Gasometers,  106, 107. 

Gay  Lussac  on  volumes,  107. 

German  silver,  (packfong,)  352. 

Gibbsite,  266. 

Gilding,  290.t 

Glass,  251,  254,297,368. 

Glass  formed  by  fused  borax,  251. 

Glauber  salt,  88,  89,  356. 

Glucina,  268,  269. 

Glucina  fluacid  of,  269. 

Glucinium,  268. 

Gold,  290. 

Golden  sulphur  of  antimony,  348. 

Gold  and  silver  coin,  263. 

Goniometer,  85. 

Goulard's  extract,  318. 

Gravimeter,  102. 

Gravity,  specific,  100, 102, 103. 

Green  vitriol,  326. 

Gypsum,  85,  357. 

Hematite,  141. 

Halogen  bodies,  or  elements,  108,  202. 

Haloid  salts,  356. 

Hardening  metals  by  refrigeration  by  the 
hammer,  263. 

Heat,  47,  48,  49,  62,  64— capacities  for,  44 
— by  condensation,  63 — for  chemical 
purposes,  64 — latent,  4 — by  solution,  62 
— radiation  of,  52 — specific,  44. 

Hexacarbohydrogen,  236,  240. 

Hexacetateoflead,  318. 

High  pressure  boiler,  35. 

High  steam,  35. 

Homogeneous  attraction,  83. 

Honystone,  322. 

Hydracids,  157.     See  Jlcids,  halohydric. 

Hydrargyrum  precipitatum  album,  309 — 
amido  bichloride  of  mercury.* 

Hydrate,  151. 

Hydrate  of  alumina,  266, 267— of  carbon,* 
220— of  chloral,  232— of  chlorine,*  156 
— of  lime,  274. 

Hydrate  of  lithia,  284— of  potash,  136,  280 
—of  soda,  281. 

Hydrated  bioxide  of  tin,  320— dioxide  of 
copper,  314 — protosulphide  of  iron,  330 
— subnitrate  of  bismuth,  322. 

Hydric  ether,  oxide  of  ethyl,  238,  273.* 

Hydrogen,  143, 156, 160,  206.* 

Hydrogen,  polysulphide  of,  170. 

Hydrometers,  101. 

Hydropneumatic  cisterns,  105. 

Hydrosublimate,  Howard's,  305. 

Hydrous  protochloride  of  iron,  329. 

Hygrometer  of  Daniell,  155. 

Hygrometers,  39. 

Hygrometic  process  of  Dalton,  by  the  dew- 
point,  155. 

Hypochlorite  of  lime,  361. 

Hyponitrites,  365. 

Hyponitrous  ether,  238.* 

Hyposulphates,  366. 

Hyposulphites,  366. 

*  See  Index  to  Organic  Chemi«try. 
t  See  Index  to  Electricity. 


Ice,  10,70,  71,74, 163. 

Ignition,  galvanic,  58,  59. 

Illustration  of  equivalents,  95. 

Implement,  chemical,  21. 

Imponderable  substances,  3. 

Indigo,  202.* 

Influence  of  air  on  apparent  weight  of 
bodies,  103. 

Influence  of  pressure  on  the  bulk  of  air,  28. 

Influence  of  solution  on  chemical  reac- 
tion, 92. 

Infusions,  hygrometer  for,  101. 

Ink,  329.*    ' 

Inorganic  chemistry  commenced,  arrange- 
ment of,  in  treating,  107. 

Inorganic  substances,  107. 

Insects,  light  evolved  by,  76. 

Insoluble  chlorides,  pretensions  to  the  sa- 
line character,  356. 

Insoluble  oxalates,  232. 

Insoluble  oxides,  356. 

Insoluble  sulphides,  366. 

Instrument  for  the  inflammation  of  small 
portions  of  gas,  219. 

lodacids,  157. 

Iodide  of  arsenic,  338 — bismuth,  324 — cy- 
anogen, 245— gold,  292— iron,  330— 
lead,  319— mercury,  307— silver,  299— 
sulphur,  140— tin,  321— zinc,  333. 

Iodides  of  carbon,  233. 

Iodine,  108,  130,131,134,297. 

Iodine  in  sea  salt,  286. 

lodo  salts,  370. 

lodous  acid,  133. 

Iridium,  293,  297,  351. 

Iron,  91 ,  245,  324— with  acids,  328— with 
carbon,  263— with  gold,  328— wire,  181. 

Isomeric  bodies,  217. 

Isomorphous  substances,  84. 

Kermes  mineral,  348. 

Kernels  of  bitter  almonds,  246  * 

Kupfer  nickel,  351. 

Laboratory  thermometer,  12. 

Lakes,  267.* 

Lamp,  Argand,  65,  235. 

Lamp  enamellers,  66. 

Lamp  without  flame,  65. 

Latent  caloric,  4. 

Laurel  water,  246. 

Lavoisier's  apparatus  for  recomposition  of 

water,  153. 
Lead,  315 — reagents  by  which  it  may  be 

precipitated  from  its  solutions,  317. 
Lead  water,  318. 
Lepidomene,  284. 
Leslie's  thermometer,  13. 
Light,  3,  75,  76",  77,  78,  79. 
Light,  chemical  effects  of,  80. 
Light  carburetted  hydrogen,  236. 
Light,  sources  of,  76— polarization  of,  80, 

81 — without  caloric,  76. 
Lime,  92,  273,  274— with  silicic  acid,  275 

with  oxides,  275 — with  water,  275. 
Lime  light,  67. 

*  See  Index  to  Organic  Chemistry. 


VI 


INDEX, 


Liquefaction  of  carbonic  acid,  229. 

Liquefaction  of  chlorohydric  acid  gas, 
163 — of  cyanogen,  241 — of  nitrous  ox- 
ide, 181. 

Liquids,  caloric  in,  50. 

Liquid  chlorohydric,  or  muriatic  acid, 
163. 

Liquid  sulphurous  acid,  138. 

Lithia,  284. 

Lithium,  284. 

Litmus,  119,268. 

Liver  of  antimony,  348. 

Loss  of  gas  by  condensation,  240. 

Luna  cornea,  299. 

Lunar  caustic,  300. 

Lungs,  action  of,  29. 

Lustre  of  metals,  263. 

Magistery  of  bismuth,  323. 

Magnesia,  270. 

Magnesite,  271. 

Magnesium,  270. 

Magnesiferous  alumina,  267. 

Magnetic  influence  of  nickel,  351. 

Magnetic  oxide  of  iron,  328. 

Malateoflead,  317. 

Malleability  of  metals,  263. 

Malleable  iron,  325. 

Manganese,  138,  354. 

Manganic  acid,  354. 

Manufacture  of  oil  of  vitriol,  193. 

Marble,  273,  357. 

Margaric  acid,  202.* 

Marsh's  apparatus,  343. 

Matter,  1,3. 

Massicot,  316. 

Maugham's  blowpipe,  so  called,  68. 

Mechanical  division,  223. 

Mechanico-chemical  agency  of  charcoal, 

223. 

Media  of  refraction,  79. 
Meconate  of  lead,  317. 
Melting  ice  by  combustion  of  carbon,  222. 
Menachanite,  355. 
Mercury,  91,  300,  301. 
Mercury,  frozen,  230. 
Mercurial  salts,  301. 
Mercurio-pneumatic  cistern,  105. 
Metallic  crystals,  87. 
Metallic  oxides,  206.t 
Metals,  197,  262,  263. 
Metals  of  alkalies,  284. 
Metals  of  earths,  264,  284. 
Metals,  expansion  of,  6,  7. 
Metals  proper,  261. 
Metameric  bodies,  244. 
Meteorolites,  324. 
Meterioric  iron,  324. 
Mineral  crystals,  87. 
Mineral  waters,  130. 
Minium,  316. 
Moisture  in  air,  154. 
Moisture  in  clay,  266. 
Molybdate  of  lead,  354. 
Molybdenum,  354. 
Moon,  light  of,  76.* 

*  See  Index  to  Organic  Chemistry. 

t  See  Essays  and  Letters  on  Nomenclature. 


Mordants,  267. 

Mortar,  275. 

Muffle,  299. 

Muriate  of  ammonia,  92. 

Muriate  of  lime,  275. 

Mytheline,    or    methyl,   235* — chlorohy- 

drate  of,  235.* 
Naphtha,  209,  229,  283.* 
Naphthaline,  235,  240. 
Native  naphtha,  241.* 
Native  protosulphide  of  iron,  330. 
Neutral  acetate  of  copper,  314. 
Neutral  nitrates,  364. 
Neutral  phosphates,  367. 
Newton  on  light,  75. 
Nickel,  351— spongy,  297. 
Nitrate  of  ammonia,  180 — of  copper,  313 

—of  cobalt,  268— of  lead,  317— of  lime, 

275— of  silver,  299— of  zinc,  332. 
Nitrates,  364. 
Nitrites,  365. 

Nitrogen,  172,  173, 174, 179,  283. 
Nitric  oxide  (nitrous  air  of  Priestley),  182, 

212. 

Nitrous  oxide,  179— liquefied,  181. 
Nituret,  or  amiduret,  of  potassium,  283.* 
Nituret,  or  amiduret,  of  sodium,  283.* 
Nituret,  or  amiduret,  of  copper,  311. 
Noble  metals,  260,  261. 
Nomenclature,  122,  136,  157, 158, 198-9. 
Nordhausen,  sulphuric  acid  of,  139. 
Numerous  compounds  of  carbon,  235. 

Obsidian,  269. 

Ochres,  327. 

Odour,  alliaceous,  of  phosphorus,  211 — of 
arsenic,  342. 

Odour  of  selenium,  140, 141. 

Oil  of  turpentine,  229,  238.* 

Oils,  fixed,  volatile.* 

Ointment,  mercurial,  300. 

Olfactory  nerves  peculiarly  affected  by 
selenhydric  acid,  171. 

Olefiant  gas,  hydruret  of  acetyl,  188,  235, 
238.* 

Ores  of  zinc,  352. 

Organic  acids,  109*— alkalies,  109. 

Osmiate  of  soda,  351. 

Osmium,  297,  351— alloys  of,  351. 

Osmiuret  of  iridium,  351. 

Oxacid  of  gold,  291.t 

Oxacids,  157,  158. 

Oxalate  of  copper,  232 — iron,  232 — lead, 
317— lime,  232— magnesia,  232. 

Oxalis  acetosella,  231 

Oxibases,  258,  285. 

Oxidability  of  metals,  263. 

Oxide  of  boron,  250 — bromine,  129 — cad- 
mium,  352— calcium,  273— cobalt,  354 
— glucinium,  269 — iridium,  351 — lith- 
ium, 284 — magnesium,  270 — magnetic, 
263,  328— of  molybdenum,  354— nitric, 
182 — nitrous,  181 — of  osmium,  351 — se- 
lenium, 141— silicon,  253 — tellurium, 
143— thorium,  270— titanium,  353,  355 
— yttrium,  269 — zirconion,  259.t 

*  See  Index  to  Organic  Chemistry. 
t  See  Index  to  Electricity. 


INDEX, 


Vll 


Oxides  of  antimony,  345 — arsenic,  335, 
336,  337— barium,  277— bismuth,  323— 
calcium,  273,  275 — chlorine,  123—  chro- 
mium, 352 — copper,  312 — gold,  291 — 
hydrogen,  156 — iron,  325,  326 — iodine, 
133— lead,  316,  317— manganese,  354— 
mercury,  302,  303— nickel,  352— nitro- 
gen, 17!) — phosphorus,  215 — potassium, 
283— platinum,  294— silver,  298— so- 
dium, 283 — strontium,  277 — sulphur, 
137— tin,  320— zinc,  331,  332. 

Oxybase  of  ammonium,  209. 

Oxy chlorate  of  potash,  127 — of  barytes, 
281— of  ethyl.* 

Oxychloride  of  antimony  345— of  bis- 
muth, 323— of  mercury,  306. 

Oxygen,  108, 110,  111,  112, 113, 114, 115* 
— acids,  157. 

Oxygenated  water,  156. 

Oxyhydrogen  blow-pipe,  66 — eudiometer, 
176. 

Oxysalts,  359. 

Oxysulphide  of  antimony,  349— of  tellu- 
rium, 143. 

Oyster  shells,  274. 

Packfong,  (German  silver,)  352. 
Palladium,  350— alloys  of,   350— sponge, 

297. 

Palm  glass,  38. 
Paracyanogen,  242. 
Paradox,  culinary,  32,  33. 
Particles,  1. 
Peach  leaf,  246. 
Pearl  ash,  280. 
Pencil  of  solar  light,  76. 
Perbromide  of  iodine,  133 — of  phosphorus, 

Percarburet  of  potassium,  283. 

Perchlorates,  364. 

Perchloride  of  antimony,  120,  345 — of  cy- 
anogen, 245— of  iodine,  133 — of  phos- 
phorus, 217. 

Percussion,  heat  produced  by,  60. 

Percussion  powder,  368. 

Periodide  of  carbon,  233. 

Perkins  on  steam,  37. 

Peroxide  of  barium,  277 — of  calcium,  275 
— of  copper,  311 — of  potassium,  283 — of 
silver,  299— of  sodium,  283 — of  stron- 
tium, 277— of  zinc,  331. 

Perphosphuretted  hydrogen,  218.t 

Persulphide  of  antimony,  345 — of  arsenic 
335,  338— of  lead,  319. 

Petalite,  284. 

Pewter,  263. 

Philosophic  candle,  147. 

Phlogiston,  196. 

Piston  valve  volumeter,  178. 

Phosphate  of  iron,  326— of  lead,  319— of 
liine,211— of  soda,  211. 

Phosphates,  366,  367.  See  Emendation, 
end  of  Index  to  Organic  Chemistry. 

Phosphites,  366. 

Phosphorescent  wave,  76. 

*  See  Index  to  Organic  Chemistry, 
t  See  Index  to  Electricity. 


Phosphorus,  114, 121, 181,211,213,363— 
combustion  of,  212 — crystallized,  212 — 
ignited  by  radiation,  53 — isomeric  acids 
of,  217— with  gold,  290. 

Phosphuret  of  arsenic,  339 — of  iron,  326 
— of  zinc,  331 — of  potassium,  283. 

Phosphurets,  366. 

Phosphurets  of  mercury,  309. 

Phosphuretted  hydrogen,  219.t 

Physical  reaction,  1. 

Physiological  reaction,  2. 

Plants  require  air  and  water,  154 — absorb 
carbonic  acid,  227.* 

Platinated  asbestos,  297. 

Platinum  or  platina,  293,  294,  295,  297. 

Platinum,  fusion  of,  68— scroll,  296— 
sponge,  74,  296,  297. 

Plumbago,  220,  223. 

Plumbum  corneum,  319. 

Pneumatic  chemistry,  83. 

Polarization  of  light,  80. 

Poles,  negative  and  positive,  197.* 

Polymeric,  235. 

Polysulphuret  of  hydrogen,  170. 

Pompholix,  332. 

Ponderable  elements,  107— fluids,  104. 

Porcelain,  268,  207. 

Porosity  of  charcoal,  55,  223. 

Porous  bodies,  223. 

Potash,  282. 

Potash,  bichromate  of,  353 — bitartrate  and 
biborate  of,  369 — manganate  of,  354. 

Potassium,  162, 178,  279— chloroplatinate 
of,  295. 

Powder,  bleaching,  172,  361. 

Precious  stones,  85,  265. 

Precipitated  sulphuret  of  antimony,  349. 

Preparation  of  oxygen,  111,  112 — of  potas- 
sium, 278. 

Pressure,  28 — of  the  atmosphere,  14,  15, 
18,  33— on  fluids,  30,  31— of  liquids,  32, 
33— modifies  boiling,  34 — restrains  che- 
mical action,  43. 

Prince  Rupert's  drops,  255. 

Principal  character  of  acids,  358 — groups 
of  salts,  358.t 

Prism,  77,  78,  80. 

Proportions,  definite,  93. 

Protobromide  of  iron,  133. 

Protochloride  of  arsenic,  335 — bismuth, 
323— carbon,  233— copper,  311,  314— 
cyanogen,  245 — gold,  291,  292 — iodine, 
133— iron,  183,  Io6,  325— mercury,  301 
306— tin,  320,  327. 

Protocyanide  of  iron,  330 — phosphuretted 
hydrogen,  318— selenide  of  copper,  315 
—sulphate  of  iron,  183,  186— sulphate 
of  tin,  320. 

Protosulphide  of  arsenic,  335,338 — copper, 
311— gold,  292— iron,  325,  330— lead, 
319— mercury,  301,  308— tin,  321. 

Protoxide  of  barium,  277 — bismuth,  323 — 
calcium,  273 — copper,  311 — iron,  325, 
326 — lead,  316 — manganese,  354 —mer- 
cury, 301— nickel,  352— nitrogen,  179 

*  See  Index  to  Organic  Chemistry, 
t  See  Emendations,  p.  xx. 


Vlll 


INDEX. 


— potassium,  280 — silver,  298 — sodium 
280— strontium,  277— tin,  320— zinc 
331. 

Prussian  blue,  330. 

Prussiate  of  potash,  330. 

Pulse  glass,  38. 

Pump,  air,  21— condensing,  27— exhaust- 
ing, 27 — forcing,  27 — lifting,  27 — water, 
19,  21. 

Purple  powder  of  Cassius,  291. 

Pyroligneous  acid,  235. 

Pyrometer,  6 — Daniell's,  7 — Wedge- 
wood's,  8. 

Pyrophorus,  112,  283. 

Pyroxylic  spirit,  235. 

Quadroxide,  137. 

Quantity  of  air  in  a  given  space  is  as  its 

pressure,  29. 
Quartz,  251,  253. 

Quick  communication  of  heat,  52. 
Quicklime,  205,  206,  274. 

Radiant  light,  75. 

Radiation  of  cold,  55 — of  heat,  55. 

Radiators,  54,  55. 

Radical  of  an  acid  or  base,  the  combustible 
body  in,  157. 

Radicals,  metallic,  110, 143— non-metallic, 
110, 143. 

Radiant  heat,  52,  56. 

Rain  storms,  non-electric,  40. 

Rarefaction,  23,  37,  39. 

Rationale  of  frangibility  of  glass,  48— re- 
frigeration of  a  jet  of  high  steam,  36 — 
diversity  of  radiating  power  of,  54. 

Rays,  chemical,  heating,  illuminating, 
56,57,78. 

Reaction,  elastic,  of  air,22 — intense  corpus- 
cular, 196 — attractive,  2 — repulsive,  2. 

Reaction  of  particles  and  masses  of  mat- 
ter, 1. 

Reaumur's  scale,  12. 

Receiver,  exhausted,  22  to  27— condensa- 
tion of  air  in,  29. 

Recomposition  of  water,  153. 

Red  cabbage,  infusion  of  as  a  test,  203. 

Red  oxide  of  copper,  311 — of  iron,  325 — 
of  lead,  354,316— of  mercury,  302. 

Reduction  of  metals,  263. 

Reflectors,  54. 

Refraction,  76,  78. 

Refrangibility  of  light,  79. 

Refrigeration,  73,  74?  234. 

Registering  thermometer,  12. 

Regulus  of  metals,  263. 

Relaxation  of  pressure  on  air,  or  rarefac- 
tion of,  produces  cold,  38. 

Remarks  on  nomenclature,  122,  136  157, 
198,  199.  See  Essays,  letters,  fyc. 

Repulsion,  2 — repulsive  influence  of  ca- 
loric, 3,  9. 

Reservoir  for  hydrogen,  144. 

Reservoirs,  self-regulating,  226. 

Respiration,  29,  227. 

Resistance  of  air,  28. 

Revival  of  metals,  263. 

Rhodium,  350. 


Rhubarb,  test  for  alkalies,  203. 

Rochelle  salt,  269. 

Rock  crystal,  56— salt,  56. 

Roll  sulphur,  136. 

Ruby,  265. 

Rumex  acetosa,  231. 

Safety  lamp,  236,  237. 

Sal  alembroth,  307— ammoniac,  204,  356. 

Saline  solutions,  101. 

Salinity,  358. 

Salts,  108,  356. 

Salts  of  the  ocean,  270 — of  potash,  282 — 

of  protoxide  of  copper,  314 — of  rhodium, 

350-of  soda,  2*2. 
Sanctorio's  thermometer,  11. 
Saturni  arbor,  86,  332,  333. 
Scale  of  equivalents,  94. 
Scales  of  iron,  328. 
Scheele's  green,  337. 
Scoria,  355. 
Selenacids,  158. 
Selenide  of  antimony,  349 — arsenic,  339 — 

bismuth,   324— iron,   330— lead,    319— 

mercury,  304— tin,  322— zinc,  333— of 

phosphorus,  217. 
Selenisalts,  369. 
Selenium,  108,  140,  141,  142. 
Selenium  acids,  or  selenacids,  157. 
Seleniurets,  or  selenides  of  phosphorus-, 

Seleniuretted  hydrogen,  171. 

Self-repellent  power  of  caloric,  55. 

Self-registering  thermometers,  12. 

Self-regulating  reservoir,  58. 

Sensible  heat  from  electricity,  57. 

Sesquibasic  phosphates,  367t — bromide  of 
phosphorus,  217. 

Sesquicarbonates,  367. 

Sesquichloride  of  antimony,  345 — of  ar- 
senic, 335,  338— of  carbon,  233— of  iron, 
325. 

Sesquicyanide  of  iron,  330. 

Sesquioxide,  137— oxide  of  aluminum, 
268— of  bismuth,  323— of  cerum,  365— 
of  chromium,  352 — of  chromium  and 
iron,  352 — of  manganese,  354. 

Sesquiphosphates,  367.t 

Sesquisulphide  of  antimony,  345,  347 — of 
arsenic,  335— of  iron,  325,  330. 

Sexsilicate  of  lead  and  potash,  368. 

Shear  steel,  325. 

Silica,  253.t 

Silicate  of  alumina,  268— of  iron,  325— of 
magnesia,  271 — of  potash,  268 — of  zinc, 
331. 

Silicates,  367. 

Silicon,  251. t 

Silicuret  of  potassium,  284. 

Silicurets,  368. 

Silver,  91,  119,  297,  298,  299— arseniate 
of,  337 — ajsenite  of,  337 — chemical  ves- 
sels, 256— coin,  298. 

Simple  affinity,  89 — combination,  89. 

Simple  valve  volumeter,  179. 

Slag,  355. 

Slaked  barytes,  or  hydrate  of,  276. 

t  See  Emendations,  end  of  Index,  p.  xx. 


INDEX, 


IX 


Slaked  lime,  or  hydrate  of,  92,  274. 

Sliding-rod  gas  measure,  178. 

Smalt,  354. 

Smell  of  arsenic,  342 — of  selenium,  141. 

Smoky  rock  crystal,  diathermane  proper- 
ties of,  56. 

Snow  and  sulphuric  acid,  73. 

Soaps,  202.* 

Soda,  92,  286. 

Sodium,  279,  230,  301— amalgam  of,  208 
— chlorhodiate,  350 — chloride  of,  285 — 
chloroplatinate  of,  295. 

Solar  rays.  57. 

Solar  spectrum,  78,  79. 

Solid  carbonic  acid,  229 — hydrate  of  chlo- 
rine, 119 — sulphuric  acid,  140. 

Solids,  circulation  of  heat  in,  47 — expan- 
sion of,  6. 

Solution,  92,  285— produces  heat  or  cold, 
62. 

Solvent  of  gold,  119. 

Sores  from  chromic  acid,  353. 

Sources  of  heat,  57,  64. 

Space,  specific  heat  of,  46. 

Specific  gravity,  83,  98.  100,  101,  103. 

Specific  heat,  44,  45,  98— of  gases,  46. 

Spectrum,  79. 

Spinelle  ruby,  265. 

Splendid  combustion,  113,  114, 115. 

Spodumene,  284. 

Spongy  indium,  297 — nickel,  297 — palla- 
dium, 297— platinum,  74,  293,  296— rho- 
dium, 297. 

Springs  of  Virginia,  169. 

Stalactite,  266. 

Stalactite,  calcareous,  226. 

States  of  caloric  in  nature,  74. 

Steam,  condensation  of,  52 — decomposi- 
tion of,  152. 

Steel,  263,  325. 

Steel  mill  for  giving  light  in  mines,  236. 

Strontia,  92,  277 — apparatus  for  evolving, 
/4/t).  t 

Strontium,  271. 

Subacetate  of  copper.  314. 

Subnitrate  of  silver,  300. 

Suboxide  of  arsenic,  335 — of  potassium, 
283— of  silver,  299— of  sodium,  283. 

Suction  pump,  19,  20. 

Sugar  of  lead,  318. 

Sulphacids,  158,  288. 

Sulphate  of  antimony,  365 — of  baryta, 
276,  365— of  bismuth,  365— of  copper, 
313— of  lead,  365— of  lime,  3&5—  of  mag- 
nesia, 89,  270— of  mercury,  365— of  sil- 
ver, 365 — of  soda,  suspended  crystalli- 
zation of,  88 — strontia.  365 — thorina, 
270— tin,  365— yttria,  365. 

Sulphates,  365. 

Sulphide  of  barium,  276— of  cadmium,  352 
— of  copper,  315 — of  hydrogen,  or  sul- 
phydric  acid,  166,  167 — of  manganese, 
354 — of  molybdenum,  354 — of  platinum, 
297— of  potash,  136— of  selenium,  142 
—of  silver,  299— of  zinc,  331,  332 

Sulphides,  135,  288,  359— of  antimony, 
349 — of  arsenic,  338— of  iron,  325— of 

*  See  Index  to  Organic  Chemistry, 
t  See  Index  to  Electricity. 


lead,  319— of  mercury,  301— of  phos- 
phorus, 217. 

Sulphites,  366. 

Sulphobases,  288. 

Sulphocyanide  of  iron,  245. 

Sulphocyanide  of  potassium,  245. 

Sulphocyanogen.  245. 

Sulphosalts,  288,  369. 

Sulphur,  108,  115,  134— chlorides  of,  140. 

Sulphurets,  sulphides,  135,  288. 

Sulphuretted  hydrogen,  160,  170.  See 
Add,  sulphydric. 

Sulphur  springs,  169,  299. 

Supercarbonate  of  magnesia.  271. 

Supporters  of  combustion,  198. 

Surfaces,  radiating,  54. 

Suroxide,  or  bioxide,  of  barium,  276. 

Symbols,  chemical,  96. 

Sympathetic  picture,  169. 

Synthesis  of  ammonia,  207 — of  chlorohy- 
dric  acid,  160 — of  nitrous  acid,  184. 

Table  of  affinity,  92— of  equivalents,  189 
— of  freezing  mixtures,  73,  74 — of  me- 
tals, 262— of  weights  of  gases,  104— of 
volumes,  189. 

Tanno  gallate  of  iron,  i.  e.  ink,  327. 

Tantalite,  354. 

Tantalum  (see  Columbium),  354. 

Tartar  emetic,  346,  368. 

Tartrate  of  iron  and  potash,  368 — of  anti- 
mony and  potash,  346,  368— of  lead,  317 
— of  potash,  282 — of  potash  and  soda, 
sal  Rochelle,  369— of  soda,  282.* 

Tartrates,  368. 

Telluriacids,  158,  289. 

Tell  urhyd  rates,  158. 

Telluribase,  200. 

Telluride  of  mercury,  304. 

Tellurides,  289,  359. 

Telluri-salts.  143,  369. 

Tellurium,  108,  142,  157. 

Temperature  and  moisture,  154. 

Tertium  quid,  109,  358. 

Test  of  arsenic.  343— of  chlorine,  119— of 
copper,  311 — of  iodine,  131— of  potash, 
282— of  silver,  119,  298— of  soda,  282. 

Tetartocarbohydrogen,  236,  240. 

Theory  of  atoms,  95 — of  chlorine,  165 — of 
electro-magnetism,  appendix — of  Mello- 
ni,  56 — of  phlogiston,  196. 

Theory  of  volumes,  187. 

Thermo-electric  batteries,  323. t 

Thermo-electric  pile,  56.t 

Thermometer  of  Sanctorio,  11. 

Thermometers,  10,  14,  36. 

Thermoscope  of  Melloni,  56. 

Thillorier's  process  for  congelation  of  car- 
bonic acid,  44,  230. 

Thomson's  equivalents,  94. 

Thorina.  269,  270. 
!  Thorite, '269. 
i  Thorium,  269. 

Tin,  89,  292,  320. 

Tinder,  221. 

Tin,  crystalline  hydrate  of,  321. 

Tin,  hydrated  bioxide  of,  320. 

I  *  See  Organic  Chemistry,  5181  to  5193,  also  5^28. 
t  See  Index  to  Electricity. 


INDEX. 


Titanium,  355. 
Topaz,  265. 

Torricellian  experiment,  17. 
Toughness  of  metals,  263. 
Transmission  of  contagion,  223. 
Triacetate  of  lead,  318. 
Tribromide  of  gold,  292. 
Trichloride  of  gold,  292. 
Trioxide  of  gold,  291. 
Trisulphide  of  gold,  292. 
Tritocarbohydrogen,  235. 
Tubulated  retort,  figure  of,  161. 
Turmeric,  203,  277. 
Turpeth  mineral,  303. 
Tungsten,  355. 
Type  metal,  89. 

Undulations  of  light,  75. 
Uranium,  355. 
Urea,  244. 

Vacuum,  43,  46,  70,  71— Torricellian,  46. 

Vanadium,  355. 

Vapour,  40, 47 — Berzelius  on,  42 — of  chlo- 
ride of  carbon,  233— ethereal,  47 — of  io- 
dine, 131— of  sulphur,  136. 

Vaporization,  31,  37,  40 — cold  produced 
by,  68— of  ice,  71. 

Vegetable  colouring  matters,  203 — char- 
coal removes  them,  222 — destroyed  by 
chlorine,  119 — by  hypochlorous  acid, 
124 — by  hypochlorites,  361. 

Velocity  of  sound  accelerated  in  hydro- 
gen, 146. 

Vinous  fermentation,  226. 

Vitality,  a  source  of  heat,  64. 

Vitrified  borax,  356. 

Vitriolated  tartar,  i.  e.  sulphati  potassa,  357 

Vitriol,  colcothar  of,  328. 

Vitriol,  oil  of,  139. 

Vitreous  compound  of  antimony,  348. 

Voice  affected  by  hydrogen,  147. 

Volatile  alkali,  204 — oxide  of  osmium,  351 
— oxide  of  selenium,  141. 

Voltaic  current,  action  of,  on  phosphorus, 
211. 

Voltaic  electricity,! — power  of  fishes,t — 
poles,  109,  197— series,  197.t 

t  See  Index  to  Electricity. 


Volumes,  187,— table  of,  189. 
Volumescope,  149,  185. 
Volumeter,  178. 

Water,  150, 151, 153,  154,  257— acts  like 
an  acid  with  bases,  151 — acts  like  an 
acid  with  lime,  274 — acts  like  a  base 
with  acids,  151— an  absorbent,  119, 163, 
227 — congelation  of,  69 — expansion  of, 
9 — frozen  by  boiling  ether,  68 — in  oxalic 
acid,  231 — of  crystallization,  87— oxy- 
genated, 156 — pump,  19 — basic,  See  Or- 
ganic Chemistry  and  Appendix,  for  es- 
says on  nomenclature,  salt,  and  radical 
theory. 

Weight  of  air,  104— of  the  atmosphere,  14, 
18— of  gases,  104— of  fluids,  104— of 
steam,  104. 

Weighing  in  vacuo,  104. 

Weights,  atomic,  96,  97. 

Welding  process,  263. 

Wheel  lap,  44. 

White  hydrate  of  iron,  326. 

White  sulphur  springs,  199. 

Wild  oat,  beard  of,  as  an  hygrometer,  39, 
155. 

Winds  from  the  African  deserts,  aridity 
of.  154. 

Winds  replete  with  aqueous  vapour,  40. 

Wire  gauze,  236. 

Wollaston's  equivalents,  94, 95 — cryopho- 
rus,  71. 

Wootz,  a  peculiar  variety  of  steel,  325. 

Woulf 's  apparatus,  163 — improved,  163. 

Yttria,  269. 
Yttrio  cerite,  269. 
Yttrio  tantalite,  269. 
Yttrium,  269— chloride  of,  285. 

Zaffre,  354. 

Zinc,  89,  331 — acetate  of,  90,  333— car- 
bonate of,  331— cyanide  of,  333— fluo- 
ride of,  333— iodide  of,  333— oxides  of, 
331— selenide  of,  333— silicate  of,  331— 
sulphate  of,  331— sulphide  of,  331. 

Zirconion,  or  zirconium,  259. 

t  See  Index  to  Electricity. 


INDEX 


TO 


THAT   PORTION   OF   THIS   COMPENDIUM 


WHICH  RELATES  TO 


ORGANIC  CHEMISTRY. 


Absinthine,  528. 

Acetal,  549. 

Acetate  of  ammonia,  460 — of  tungsten, 
and  of  molybdenum,  459 — of  oxide  of 
amyl,  562 — of  pepsine,  575. 

Acetates  of  lead,  459,  460,  498. 

Acetated  oxide  of  ethyl,  acetic  ether,  542, 

Acetone,  391. 

Acetous  fermentation,  596,  598. 

Acetyl,  or  acetule,  377, 392, 547— chloride 
of,  549,  550— chlorohydrate  of  chloride 
of,  549 — oxychloride  of,  550 — trioxide 
of,  457 — trioxide  hydrated,  456. 

Acid,  acetic,  379,  456,  458,  547,  597— ace- 
tous, 471,  547— aldehydic,  547— allox- 
anic,  488 — azomaric,  445 — benzole,  382, 
441,  450,  476,  492,  588— bromohydric, 
479— bromosaliculic,  482— butyric,  425 
— caffeic,  473— caflfee  tannic,  473— ca- 
pric,  425 — caproic,  425 — carbonic,  372, 
375, 583, 584, 586*— cerebric,  573— chlo- 
ric, 453 — chlorochromic,  482 — chloro- 
proteic,  564 — chlorosaliculic,  481 — cho- 
leic,  576,  589— cholic,  577— choloidic, 
577,  588 — cholopholic,  445 — cinnamic, 
383,  450— citric,  461— citraconic,  462— 
cocoastearic,  425 — crotonic,  425 — cyan- 
hydric,  375* — cyanoxalic,  484 — cyan- 
uric,  455 — delphinic,  425 — dialuric,  490 
— elaidic,  429— erythric,  487— ethalic, 
426 — ethero-sulphurous,  537 — ethionic, 
530 — fellinic,  577 — formic,  471 — formo- 
benzulic,  478 — formous,  471 — fumaric, 
462 — fuming  nitric,  449* — gallic,  455, 
467 — glucic,  470 — guaiacinic,  464 — hip- 
puric,  383,  477,  492,  588— humic,  584— 


h 

nap 


yposulphobenzoic,  475 — hyposulpho- 
aphthalio,475 — hyposulphurous,475 — 
iodosaliculic,  482 — isethionic,  475,  530 
— itaconic,  462— kacodylic,  393 — lactic, 
460,  568,  598— lignosulphuric,  410- li- 

*  See  Inorganic  Chemistry. 


thofellic,  578 — malic,  462 — margaric, 
425,  447— meconic,  451,  469,  497— me- 
lanic,  481— melassic,  470— mesoxalic, 
488 — mucic,  399,  471 — mycomelinic, 
488 — myristicic,  425 — myronic,  597 — 
nitric,  453* — nitroso-nitric,  433* — nitro- 
saliculic,  482— oleic,424, 425,447— oleo- 
phosphoric,  572, 573 — oxalhydric,  470 — 
oxalic,  372* — oxaluric,  488— palmatic, 
422— parabanic,  486,  488— paratartaric, 
462 — pimaric,  445 — pinic,  445 — pyro- 
gene,  455 — pyroligneous,  440 — pyro- 
maric,  445 — racemic,  462 — ricinic,  425 
— ricino  oleic,425— ricino  stearic,  425— 
saccharic,  470 — salicohydric,  479 — sali- 
culic,  481 — saliculous,  479,  521 — salicy- 
lous,  479— stearic,  425,  447 — succinic, 
453,  476— sulphoamylic,  396— sulpho- 
cyanhydric,  470*— sulphogly  eerie,  397 — 
sulphomethylic,474 — sulphoproteic,564 
— sulphosaccharic,  475 — sulphovinic, 
474,  532— sulphuric,  497*— sylvic,  445 
tannic,  465,  473— tartaric,  417,  462— 
tartralic,  463 — tartrovinic,  474 — thionu- 
ric,  488— uramilic,  489,  490— uric,  484, 
485,  579 — uric  anhydrous,  486 — valeri- 
anic,  473,  562— xan'thoproteic,  564. 

Acidifiable  radicals,  377. 

Acids,  bibasic,  454,  456 — from  gaultheria, 
482-— from  sugar,  470 — monobasic,  454 
— polybasic,  471 — pyrogene,  455 — tri- 
basic,  454,  456 — volatile,  427. 

Aconitia,  or  aconitine,  512. 

Aconitum  napellus,  512. 

Adjective  dyes,  419. 

Agedoile,  523. 

Albumen,  41 1 ,  564, 565,  566— animal,  413, 
415— vegetable,  413,  415. 

Alcargen,  alcarsin,  393. 

Alcohol,  374,  384,  468,  547,  598— amylw, 
561— ethylic,  384— methylic,  552. 

*  See  Inorganic  Chemistfy. 


Xll 


INDEX. 


Alcornine,  528. 

Aldehyde,  389,  547,  548 — ammoniated, 
548— mesitic,  560,  561— resin  of,  549. 

Alismine,  528. 

Alkalies,  organic,  493,  496— vegetable, 
493,  494. 

Alkaloids,  493. 

Allaritoin,  487. 

Alloxan,  486,  487— hydrated,  490. 

Alloxatin,  486,  489— dimorphous,  490. 

Almonds,  bitter,  oil  of,  432,  441. 

Aloes,  451. 

Altheine,  523. 

Alumina,  419.* 

Amanitine,  528. 

Amber,  443,  452. 

American  oil,  453. 

Amide,  372,  377,  380. 

Amido  chloride  of  mercury,  376,  381. 

Amido  subnitrate  of  mercury,  381. 

Amidurets,  376. 

Amiduret  of  benzule,  442 — of  hydrogen, 
380. 

Ammeline,  and  ammoline,  496. 

Ammonia,  371,  380,  586* — benzoate  of, 
477 — cyanate  of,  579 — hamate  of,  584 — 
magnesian  phosphate  of,  582 — purpu- 
rate  of,  490— saliculite  of,  480— urate 
of,  582. 

Ammoniac,  451. 

Ammoniacai  gas,  434.* 

Ammonium,  372,  376,  380,  392*— oxide 
of,  455. 

Amygdaline,  383. 

Amyl,  or  amule,  377,  395 — bromide  of, 
562— ethers,  561— iodide  of,  562. 

Amylic  alcohol,  561. 

Analysis  of  blood,  570— organic,  497 — ul- 
timate, 374 — of  urine,  581. 

Angustura,  false,  505. 

Anilina,  or  aniline,  519,  520. 

Anhydrous  formic  acid,  556. 

Animal  growth,  582 — life,  586 — products, 
372— substances,  563. 

Animine,  496. 

Anodyne,  Hoffman's,  534. 

Anthracite,  452. 

Antiaria,  or  antiarine,  516,  528. 

Ants,  471. 

Aorta  of  the  ox,  595. 

Apirine,  496. 

Aqua  ammoniae,  431.* 

Arabin,  399 — rnetamorphic,  399. 

Aricine,  504. 

Arterial  fibrine,  567. 

Arthanitine,  527. 

Artificial  camphor,  439 — cold,  539 — diges- 
tion, 590 — fat,  425 — fibrin,  567— naph- 
tha, 453— oil  of  ants,  557— tannin,  466. 

Asclepine,  528. 

Asparagine,  523. 

Asparamide,  523. 

Asafcetida,  446,  451. 

Association  of  vegetable  bodies,  375. 

Astringency,  465. 

Atropia,  atropine,  512,  519. 

*  See  Inorganic  Chemistry. 


Azaridine,  496. 

Balsam  of  Peru,  383— Tolu,  383,  450. 

Balsams,  450 

Basacigen  class,  376. 

Base,  377. 

Bases,  organic,  493. 

Basic  equivalents,  455. 

Basic  saliculate  of  lead,  480. 

Basic  sulphate  of  quinia,  503. 

Basic  water,  453,  455. 

Bassorin,  399,  452. 

Bdellium  resin,  446. 

Beans,  568. 

Bean,  tonka,  481. 

Beer,  Bavarian  process  for,  597. 

Beeswax,  447. 

Belladonia,  or  belladonine,  513. 

Bengal  opium,  526. 

Benzamide,  383,  442. 

Benzole,  438. 

Benzoated  oxide  of  ethyl,  544. 

Benzoic  ether,  544. 

Benzoate  of  ammonia,  477. 

Benzoile,  377. 

Benzule,  377. 

Benzule,  or  benzyl,  377,  382 — hydruret 
of,  441. 

Berbina,  519. 

Bezoar  stones,  578,  589. 

Biamido  sesquinitrate  of  mercury,  331. 

Biamido  sulphate  of  mercury,  381.     . 

Bibasic  acids,  454,  456. 

Bichloride  of  formyl,  557. 

Bichlorinated  chloride  of  methyl,  556. 

Bichlorinated  oxide  of  methyl,  556. 

Bihydramide,  380. 

Bihydrate  of  etherine,  385. 

Bihydruret  of  amide,  380. 

Bile,  576,  587— acids  of,  576,  577— sugar 
of,  578. 

Biliary  calculi,  573,  576,  578. 

Biline,  577. 

Biliverdine,  577. 

Bioxide  of  lead,  486.* 

Bisulphide  of  ethyl,  546. 

Bitter  almonds,  oil  of,  or  hydruret  of  ben- 
zule, 382. 

Bitumen,  374,  452. 

Black  elder,  457. 

Blanchinine,  496. 

Blood,  analysis  of,  570 — arterial,  567 — 
menstrual,  567 — venous,  567,  595. 

Bone  earth,  574 — bones,  573. 

Brain,  572. 

Bread,  leavened,  417. 

Brewing,  Liebig  on  Bavarian  process  of, 
597. 

Bromide  of  acetyl,  550. 

Bromide  of  amyl,  562— of  ethyl,  545. 

Bromine  with  formyl,  557. 

Bromoform,  558. 

Bromohydrate  of  bromide  of  acetyl,  550. 

Bromosaliculic  acid,  482. 

Brucia,  or  brucine,  505. 

Bryonia  alba,  525. 

Bryonine,  525. 

*  See  Inorganic  Chnmistry. 


INDEX. 


Xlll 


Buenine,  528. 
Butter,  422. 
Butyrin,422,425. 
Buxine,  496. 

CafFeina,  or  caffein,  495,  510. 
Calcium,  372.* 
Calculi,  578,  582. 

Calculus,  fusible,  582— mulberry,  582, 588. 
Camphelene,  440. 
Camphene,  440. 
Camphogen,  432. 
Camphor,  artificial,  439. 
Camphor,  438. 
Camphor,  liquid,  438. 
Candle,  necessity  of  wick  to  a,  430. 
Cane  sugar,  402. 
Canelline,  528. 
Caoutchouc,  371,  448,  449. 
Caoutchouchine,  432,  448. 
Caprin,  422,  425. 
Caproin,  422,  425. 
Caramel,  403. 
Carapine,  496. 
Carbamide,  381. 
Carbon,  371.* 
Carbon,  hydrates  of,  373. 
Carbon,  hydrurel  of,  438. 
Carbon,  perchloride  of,  556. 
Carbonic  ether,  543. 
Carbohydrogen,  562. 
Carbonic  oxide,  375. 
Carmine,  420. 

Garni vora,  urine  of,  581,  590. 
Cascarilline,  528. 

Caseine,  568,  569,  411,  418,  564,  567. 
Cassiine,  528. 
Castor  oil,  427. 
Castine,  496. 
Catalysis,  599. 
Catechu  mimosa,  469. 
Cathartine,  525. 
Cellulose,  410. 
Centaurine,  528. 
Cerain,  447. 
Cerasin,  399. 
Cerifera,  447. 
Cerine,  447. 
Cerosie,  448. 
Cetene,  398. 
Cetraria  islandica,  525. 
Cetrarine,  525. 

Cetule,  or  Cetyl,  377, 398, 425, 562— chlo- 
ride of,  398— hydrated  oxide  of,  398. 
Charcoal,  or  carbon,  372.* 
Chelidonia,  chelidonine,  512. 
Chelerythrina,  495,  5H. 
Chelerythrine,  495,  511. 
Chemical  type,  378. 
Chemico-electric  reaction,  409. 
Chicoccine,  496. 
Chinova  bark,  496. 
Chinova  bitter,  526. 
Chloral,  551. 
Chlorarsin,  393. 
Chloride  of  acetyl,  549,  550. 
Chloride  of  calcium,  374,  433. 

*  See  Inorganic  Chemistry. 


Chloride  of  ethyl,  545. 

Chloride  of  mesityl,  560. 

Chloride  of  methyl,  556. 

Chlorides,  377.* 

Chlorides  of  forrnyl,  395. 

Chlorine  ether,  549. 

Chloroform,  558. 

Chlorohydrate  of  chloride  of  formyl,  558. 

Chlorohydruret,  496,  502,  504. 

Chlorohydruret  of  cinchonia,  504. 

Chlorophyll,  420. 

Chloroplatinate  of  chloride  of  acetyl,  550. 

Chlorosalicine,  522. 

Chlorosaliculimide,  482. 

Chloroxalic  ether.  550. 

Choleateofiead,  577. 

Choleate  of  soda,  578. 

Cholesterine,  570,  573. 

Chondrine,  572. 

Chromate  of  lead,  375. 

Chyle,  576. 

Chyme,  576. 

Cider,  457,  598. 

Cinchonia,  or  cinchonine,  494,  504. 

Cinnamon,  oil  of,  440. 

Cinnamule,  or  cinnamyl,  377. 

Cinnamyl,  hydrate  of,  450. 

Cinnarubrin,  445. 

Cisampelina,  or  cisampeline,  495,  518. 

Clay,  431. 

Classes  of  radicals,  377. 

Cloves,  oil  of,  440. 

Coagulated  caseine,  568. 

Coal,  mineral,  452. 

Coal,  naphtha,  432. 

Cocoa,  analogous  effects  as  food  to  those 

of  coffee  and  tea,  592. 
Cocoa  stearine,  422. 
Cochineal,  420. 

Codeia,  or  codeine,  451,  494,  501,  519. 
Coffee  seeds,  473,  514,  592. 
Colchicina,  or  colchicine,  495,  508. 
Colchicum,  507. 
Colletine,  528. 
Colocynthine,  525. 

Colophonium,  colophony,  or  rosin,  442. 
Colouring  matter,  vegetable,  or  dyes,  419. 
Columbine,  526. 
Compound  element,  376. 
Compound  radicals,  375,  377. 
Compounds  of  proteine,  591. 
Conina,  or  coneine,  495,  514. 
Contraction  of  arteries,  595. 
Copaiva,  446. 
Copal,  446,  453. 

Copper,  carbonate,  403— subacetate,  403.* 
Coradalina,  or  coradaline,  495. 
Coriarine,  528. 
Cornine,  528. 
Corticine,  528. 
Corydalina,  519. 
Crotonine,  422,  496. 
Crystallizable  sugars,  400. 
Cubebs,  527. 
Cubebine,  527. 
Cucumis  colocynthis,  525. 
Currants,  462. 

*  See  Inorganic  Chemistry. 


XIV 


INDEX, 


Currarina,  or  currarine,  495. 
Cyanapine,  496. 
Cyanarsin,  393. 
Cyanate  of  ammonia,  579. 
Cyanide  of  methyl,  555. 
Cyanides,  377.* 
Cyanoferrite  of  quinia,  503. 
Cyanogen,  372,  377.* 
Cyclamine,  527. 

Dalleiochin,  504. 
Daphnine,  496,  528. 
Datiscine,  528. 
Daturia,  513. 

Dehydrogenation  of  ethyl,  547. 
Delphia,  or  delphine,  506. 
Delphinine,  422. 
Density  of  essential  oils,  434. 
Derivative  radicals,  379. 
Dextrine,  407,  408. 
Diabetic  urine,  401. 
Diamond,  372.* 
Diastase,  407,  409. 
Digestion,  artificial,  590. 
Digitaline,  496. 
Diosmine,  528. 
Distillation,  373— dry,  382. 
Dulcamara,  509. 
Dyeing,  419. 
Dyes,  419. 
Dyslisine,  577. 

Elaldehyde,  549. 

Elaopten,  431,438. 

Elaterium,  525. 

Emetia,  or  emetine,  508. 

Emulsin,  383. 

Equivalents,  basic,  455. 

Ergot,  401. 

Ergotine,  526. 

Ery  throprotide  of  potash,  565. 

Esenbeckine,  496. 

Essential  oils,  371,  433,  441. 

Ether,  acetic,  542 — benzoic,  544 — bichlo- 
rine,  549 — carbonic,  543 — chlorine,  549 
— formic,  543 — oenanthic,  544 — oxalic, 
382,  543— sulphuric,  529— sulphurous, 
537. 

Etherine,  385. 

Etherple,  533. 

Ethers,  simple,  545 — formyl,  556. 

Ethyl,  or  ethule,  377,  384,  386— bisulphide 
of,  546 — bromide  of,  545 — chloride  of, 
545_compounds  of,  386 — cyanide  of, 
546 — formiated  oxide  of,  543 — hydrated 
oxide  of,  544 — oxide,  citrate  of,  544 — 
cenanthated  oxide  of,  544 — iodide  of,  545 
— selenide  of,  546 — sulphide  of,  545 — 
sulphydrate  of  the  sulphide  of,  546 — 
tartrate  of  the  oxide  of,  544— telluride 
of,  546. 

Eupatorine,  496. 

Euphorbine,  496. 

Euphorbium,  451. 

Excrements,  human,  578. 

Exostosis,  574. 

*  See  Inorganic  Chemistry. 


Fagine,  528. 

False  angustura,  505. 

Fat,  421— of  animals,  592. 

Feathers,  572. 

Fecula,  399— with  potash.  407— with  io- 
dine, 407. 

Fennel,  436,  439. 

Fermentable  matter  of  diabetes,  405. 

Fermentation,  596,  598,  604. 

Fibrin,  411,  415,  567— arterial,  567— ve- 
nous, 567. 

Fixed  oils,  426,  429. 

Flax,  409. 

Fluoride  of  calcium,  574. 

Fluorides,  377. 

Fluorine,  372. 

Food  in  cold  climates,  587 — in  warm  cli- 
mates, 587— of  vegetables,  583. 

Formiated  oxide  of  ethyl,  543 — of  methyl, 
557. 

Formic  ether,  543. 

Formulae  of  resins,  446. 

Formyl,  or  formule,  377,  395,  557. 

Fossil  copal,  446. 

Fraxinine,  528. 

Fumarine,  496. 

Galbanum,  451. 

Gamboge,  451. 

Gas,  chlorohydric  acid,  530. 

Gastric  juice,  576. 

Gaultheria,  479,  482,  521. 

Gelatine,  571,591. 

Gelatinous  tissue,  571. 

Gentianine,  524. 

Geraniine,  528. 

Glass  bulbs,  analysis  of  volatile   liquids 

by,  375. 
Glaucine,  496. 
Glaucopicrine,  496. 
Gliadine,  412. 
Globuline,  569,  570. 
Glue,  412.     See  Gelatine. 
Gluten,  409,  411,  412. 
^Glycerine,  397. 

Glyceryl,  or  glycerule,  377,  396,  562. 
Graminivorous  animals,  415. 
Granatine,  528. 
Grape  sugar,  403,  404. 
Gravel,  588. 
Grey  part  of  brain,  573. 
Guacine,  528. 
Guaiacine,  464,  526. 
Guaiacum,  526. 
Guano,  485. 
Guarana,  510. 
Gum,  373,  399,  586— arabic,  399— elastic, 

448— Senegal,  399— tragacanth,  399. 
Gypsum,  583. 

Hair,  566. 

Halogen  bodies,  382.* 
Harmalina,  519. 

Heat  by  arterial  contraction,  Winns'  hy- 
pothesis, 595. 
Heavy  oil  of  wine,  476. 

*  See  Inorganic  Chemistry. 


INDEX. 


XV 


Hederina,  518. 

Hematosin,  594. 

Hemp,  fibres  of,  409,  410. 

Hesperidine,  528. 

Hippurates,  478. 

Hoffman's  anodyne,  534. 

Horn,  566,  572." 

Honeycomb,  446. 

Humate  of  ammonia,  584. 

Humus,  584. 

Hydrate  of  etherine,  385— of  potash,  374— 

of  soda,  374. 
Hydrated  oxide  of  acetyl,  547 — of  amyl, 

473,  561— of  ethyl,  385,  534— of  formyl, 

395__of  methyl,  394,  552. 
Hydruret  of  amide,  380—  of  benzule,  382, 

441 — of  cinnamyl,  383. 
Hypoacetate  of  ammonia,  548. 
Hypoacetous  acid,  390. 
Hyponitrate  of  oxide  of  methyl,  554. 
Hyponitrous  ether,  539. 
Hypothetical  radical,  384. 
Hyssopine,  528. 

Ilicine,  528. 
Imperatorine,  527. 
Impure  iodide  of  mesityl,  560. 
Impurities  of  rain  water,  583. 
Influence  of  heat,  373. 
Insipid  sugar,  405. 
Insoluble,  or  coagulated  fibrine,  567. 
Iodide  of  amyl,  562— of  ethyl,  545— of  me- 
thyl, 555. 

Iodides,  377— iodides,  alkaline,  519. 
Iodine,  372.* 
Ipecacuanha,  508. 
Iron,  372,  595. 
Islandica  cetraria,  525. 
Isinglass,  571. 
Ivory  black,  574. 

Jamaicina,  or  jamaicine,  496,  518. 

Jervina,  or  jervine,  508,  519. 

Juice,  gastric,  576,  591 — pancreatic,  576. 

Kacodule,  or  kacodyl,  377,  393 — chloride 
of,  393 — cyanide  of,  393 — hydrated  tri- 
oxide  of,  393— oxide  of,  393— sulphide 
of,  393. 

Kreosote,  432,  440,  441. 

Lactin,  404,  574. 

Lactucarium,  526. 

Lactucine,  526. 

Lakes,  419. 

Lapathine,  528. 

Law  of  substitution,  379. 

Lentils,  568. 

Leucine,  565. 

Life,  changes  during,  582. 

Light,  polarized,  408* — polarization  of,  by 

dextrine,  408— by  starch,  408— by  su 

gar,  402. 

Lignin,  373,  407,  408,  409,  452. 
Lignosulphuric  acid,  410. 
Lignone,  559. 
Ligus trine,  528. 

*  See  Inorganic  Chemistry. 


Lilacine,  528. 
Lime,  oxalate  of,  582. 
Lime-water,  374. 
Liquid  camphor,  438. 
"  iquorice  sugar,  405. 
Liquids,  375. 
Liriodendrine,  528. 
Lobelia  inflata,  515. 
Lobelina,  515. 
Lobeline,  515. 
Lupuline,  526. 
Lute,  chemical,  448. 
Lymph,  579. 

Maceration,  433. 
Magnesia,  497. 
Magnesium,  372. 
Maize,  414. 
Malt  wort,  409. 
Manna,  406. 
Manna  sugar,  460. 
Mannite,  406,  460. 
Manures,  585. 
Margarine,  422,  425. 
Meadow  saffron,  507. 
Meconin,  451 ,  452. 
Meconine,  527. 
Meconium,  588. 
Melamine,  520. 
Melampyrine,  528. 
Mellon,  377,  379. 

Membrane,  arterial  composition  of,  572. 
Menispermia,  519. 
Menispermine,  496. 
Menthen,  459. 
Menyanthine,  528. 
Mercaptan,  546. 
Mesite,  559. 
Mesiten,  559. 

Mesityl,  or  mesitylene,  377,  560. 
Metacetone,  391. 
Metaldehyde,  549. 
Methal,  560. 

Methyl,  or  methule,  377,  394,  471 — com- 
pounds of,  556 — cyanide  of,  555 — ethers, 

Methylal,  557. 

Methylic  alcohol,  552— ether,  551— mer- 

captan,  555. 

Methylous  hyponitrous  ether,  554. 
Milk,  404,  457,  460,  574. 
Mineral  coal,  374,  452. 
Mineral  naphtha,  432. 
Modifications  of  proteine,  564. 
Molasses,  401. 
Molybdenum,  peculiar  insolubility  of  its 

acetate,  459. 

Momordica  elaterium,  525. 
Monobasic  acids,  454,  455 — salts,  456. 
Monkhood,  512. 
Mordants,  419. 
Morphia,  or  morphine,  498. 
Mould,  585. 
Mucus,  579. 
Mudarine,  525. 
Mulberry  calculus,  582,  588. 
Murexide,  490,  491. 

*  Se«  Inorganic  Chemistry. 


XVI 


INDEX. 


Muriate  of  morphia,  500. 
Muscular  fibre,  570— tissue,  570. 
Mushrooms,  401 — sugar  of,  405. 
Myrica  angustifolia,  447. 
Myricine,  447. 
Myristicine,  422. 
Myrrh,  451. 
Myrtleberries,  447. 

Naphtha,  452— artificial,  453. 

Naphthene,  452. 

Naphthol,  452. 

Narceia,  451,501. 

Narcitine,  528. 

Narcotina,  or  narcotine,  451,  501. 

Nervous  matter,  572. 

Neutral  organic  principles,  521. 

Neutral  sulphated  oxide  of  methyl,  553. 

Nicotina,  or  nicotine,  515,  520. 

Night  shade,  509. 

Night  soil,  cause  of  efficacy  as  manure, 

Nitrated  hydruret  of  cinnamyl,  383. 
Nitrated  oxide  of  methyl,  553. 
Nitrogen,  372.* 
Nutrition  and  growth,  582. 

Oak  galls,  465. 

Oats,  gluten  in,  414. 

Odorine,  496. 

CEnanthated  oxide  of  ethyl,  544. 

CEnanthic  ether,  544. 

Oil  of  amber,  453 — of  ants,  artificial,  557 — 
of  anise,  439— of  asarurn,  439— of  bella- 
donna, 428— of  bitter  almond,  384,  432 
— of  black  mustard,  432,435 — of  cloves, 
440— of  cinnamon,  383,  440— of  cubebs, 
439— of  elecampane,  439— of  fennel,  439 
— of  hops,  435 — of  horse-radish,  435 — 
of  mustard,  517 — of  parsley,  439 — of 
peppermint,  439 — of  potato  spirit,  473 — 
of  olives,  423 — of  onions,  435 — of  rose, 
439 — of  sassafras,  445 — of  spirea  ulrna- 
ria,  384, 483 — of  sunflower,  428— of  tur- 
pentine, 439 — of  water-pepper,  435 — of 
wine,  533 — >of  wine,  heavy,  533. 

Oils  and  fat,  421. 

Oils,  fixed,  421,426. 

Ole-essence,  431. 

Olefiant  gas,  549.* 

Olein,  422,  425. 

Olivile,  528. 

Olivine,  528. 

Opium,  451. 

Organic  alkalies,  498— hydrates,  373— sub- 
stances, 371— tissues,  372. 

Osmazome,  570. 

Oxacids,  464.* 

Oxalate  of  ammonia,  381. 

Oxalated  oxide  of  ethyl,  543 — oxide  of 
methyl,  555. 

Oxalic  ether,  543. 

Oxalurate  of  ammonia,  490. 

Oxamide,  381,382. 

Ox  bile,  588. 

Oxide,   carbonic,   381— of  copper,   374— 

*  See  Inorganic  Chemistry. 


cystic,  582— of  ethyl,  385— of  glyceryl, 
397— of  mesityl,  560— of  methyl,  551. 

Oxides,  377. 

Oxidized  iron,  use  of,  as  a  mordant,  419. 

Oxychloride  of  acetal,  550. 

Oxygen,  371.* 

Oxygen,  volatile  oils  containing,  436. 

Oxysulphide  of  acetal,  550. 

Pahnatine,  422. 

Palm  oil,  422. 

Papin's  digester,  505. 

Paraffin,  452. 

Paramenispermine,  496. 

Paramorphia,  451,  500. 

Peas,  legumen  or  vegetable  caseine   in, 

414,  568. 
Peat,  585. 
Pepsine,  575. 

Perbromide  of  formyl,  557. 
Perchlorate  of  oxide  of  ethyl,  541. 
Perchloric  ether,  541. 
Perchloride  of  carbon,  556. 
Perchloride  of  formyl,  557,  558. 
Perchlorinated  oxide  of  methyl,  556. 
Periodide  of  formyl,  557. 
Phenomena  of  fermentation,  600,  602, 603. 
Phloridzeine  and  phloridzine,  523. 
Phosphate  of  ammonia,  582 — of  lime,  415. 

574,  582. 

Phosphorus,  372,  415. 
Phillyrine,  528. 
Picrolichenine,  525. 
Picromel,  578. 

Picrotoxia,  or  picrotoxine,  516,  519. 
Pigmentum  nigrum,  572. 
Piper  cubeba,  527. 
Pitayine,  496. 

Platina  sponge  and  black,  471,  600.* 
Plumbagine,  526. 
Polarized  light,  408.* 
Polygala  senega,  526. 
Poplar,  384. 
Poppy,  519. 
Populine,  528. 
Potash,  497. 
Potassium,  372,  385.* 
Prirnuline,  528. 

Principles  devoid  of  nitrogen,  524. 
Proof  spirit,  best  solvent  for  gum  resins, 

451. 

Proteine,  564 — compounds  of,  591. 
Prolide,  565. 

Protochloride  of  formyl,  557. 
Pseudomorphia,  451,  500. 
Pteleyle,  560— chloride  of,  560— nitrated 

oxide  of,  560. 
Pus,  579. 

Putrefactive  fermentation,  604. 
Pyretine  resins,  443. 
Pyrethrine,  528. 
Pyrogene    acids,    455 — oils,  443— resins, 

443. 
Pyroxylic  spirit,  394,  552. 

Quadroxide  of  nitrogen,  490. 

*  See  Inorganic  Chemistry. 


INDEX. 


XV11 


Quassine,  526. 

Queen  of  the  meadow,  384. 

Quinia,  or  quinine,  501,  519. 

Quinia,   basic   sulphate   of,   502— neutral 

sulphate  of,  503— phosphate  of,  503— 

salts  of,  503,  504. 
Quinquina  bark,  496. 

Radicals,  compound,  primitive,  deriva- 
tive, 379. 

Reagents,  chemical,  520. 

Rennet,  alleged  cause  of  its  efficacy,  568. 

Repulsion,  430. 

Resins,  442 — saponification  of,  444 — table 
of,  446. 

Resin  of  aldehyde,  549— benzoin,  446— 
colophony,  445 — copal, 446 — guaiac,446 
sandarach,  446. 

Rhamnine,  528. 

Rhus  vernix,  443. 

Ricino  olein,  425. 

Ricino  stearine,  425. 

Rickets,  574, 

Rising  of  wheat  dough,  317. 

Rosin,  442. 

Rotation  of  crops,  586. 

Rutuline,  523. 

Rye,  gluten  in,  414. 

Sabadilla,  507,  519. 

Saccharine  fermentation,  597. 

Sago,  406. 

Salacin,  384,  521,  522. 

Saliculites,  480. 

Saliculite  of  potash,  480. 

Salicyl,  or  salicule,  377,  384. 

Salicyl,  hydruret  of,  521. 

Saliretine,  522. 

Saliva,  575. 

Salivary  glands,  575. 

Salt.* 

Salts  of  morphia,  500. 

Salts  of  ethyl,  544. 

Sambucus  niger,  457. 

Sanguinarine,  496. 

Santonine,  524. 

Saponine,  526. 

Sassarubrin,  445. 

Saxon  blue,  420. 

Scammony,  451. 

Scilla,  maritima,  525. 

Scillitine,  525. 

Scordine,  528. 

Scutellarine,  528. 

Secretions,  574. 

Secretory  products,  372. 

Semen  cynte,  524. 

Seneca  oil,  453. 

Senegine,  526. 

Serpentarine,  528. 

Serosity  of  the  blood,  570. 

Sesquibasic  acetate,  460. 

Sesquicarburet  of  nitrogen,  377. 

Sesquioxide  of  iron,  470. 

Sexbasic  acetate  of  lead,  460. 

Siccative  oils,  428. 

*  See  Inorganic  Chemistry. 
C 


Silicon,  371,  372.* 

Silver,  saliculite  of,  481. 

Simple  ethers,  545. 

Sinapoline,  435. 

Skins  of  animals,  571. 

Smilacine,  526. 

Smilax  sarsaparilla,  526. 

Soda,  choleate  of,  578. 

Soda,  hyponitrite  of,  539— nitrate  of,  586. 

Soil  for  potatoes,  585. 

Solanacae,  519. 

Solania,  or  salanine,  509. 

Solvent  of  oils,  433,434. 

Spartine,  528. 

Spermaceti,  398,  444. 

Spigeline,  528. 

Spirea  ulmaria,  479. 

Spirit  of  Mindererus,  460. 

Staphisia,  519. 

Starch,  373,  406,  586. 

Starkey's  soap,  434. 

Stavesacre,  506. 

Stearate  of  potash,  425. 

Stearine,  422. 

Stearopten,  431,  438,  481. 

Stones,  bezoar,  578,  589. 

Straw,  410. 

Strychnine,  505. 

Strychnos,  nux  vomica,  505. 

Suavin,  401. 

Subordinate  radicals,  377. 

Substantive  dyes,  419. 

Suet,  444. 

Sugar,  373,  399,  401 — anhydrous  grape, 
403— of  bile,  578— of  the  cane,  402— 
diabetic,  402 — grape,  402 — liquorice,  402 
— of  manna,  402 — of  milk,  402,  404 — 
mushroom,  402,  405— of  lead,  460— un- 
fermentable,  405,  406 — acts  as  an  acid, 
403. 

Sugars,  400. 

Sulpharsin,  393. 

Sulphate  of  ether,  475. 

Sulphate  of  ether  and  water,  474. 

Sulphated  oxide  of  elayl,  475. 

Sulphate  of  indigo,  420. 

Sulphide  of  ethyl,  545— of  methyl,  555. 

Sulphocyanide  of  potassium,  575. 

Sulphur,  372,  415. 

Sulphuric  ether,  529. 

Sulphurous  ether,  537. 

Summer  strained  oil,  422. 

Surinamina,  or  surinamine,  496,  518. 

Sweat,  457. 

Sweet  spirits  of  nitre,  540. 

Symbols,  377. 

Synaptase,  383. 

Synthesis,  372. 

Syrups,  400. 

Table  of  alkalies,  494,  495. 
Table  of  oxygen  oils,  436. 
Tallow,  426,  444. 
Tanacetine,  528. 
Tanghinine,  527. 
Tannin,  artificial,  466. 

*  See  Inorganic  Chemistry. 


XV  111 


INDEX. 


Tantalum,  466. 
Tapioca,  406. 
Taraxacine,  523. 
Tartar,  cream  of,  462. 
Tartarized  iron,  462. 
Tartrate  of  potash  and  soda,  462. 
Tar  water,  440,  592. 
Taurine,  577. 
Tawed  leather,  571. 
Tea,  510. 
Teeth,  574,  592. 
Terebene,  440. 
Tests  of  morphia,  500,  520. 
Thebaina,  or  thebaine,  500,  519. 
Theine,  510,  592. 
Theobromia,  519. 
Thiosinnamina,  517. 
Titanium,  466. 
Tobacco,  oil  of,  428. 
Tonka  bean,  481. 
Torrefaction,  407. 
Trernelline,  528. 
Trioxide  of  acetyl,  457. 
Tungsten,  peculiar  insolubility  of  its  ace- 
tate, 459. 
Turpentine,  oil  of,  433. 

Ulmin,  452. 

Ultimate  analysis,  371. 

Uncrystallizable  sugars,  401. 

Uramile,  489, 490. 

Urate  of  ammonia,  485, 582. 

Urate  of  potash,  485. 

Urea,  579. 

Urea,  nitrate  of,  580. 

Uril,  484,  487. 

Urinary  calculi,  582. 

Urine,  457,  492,  579— acid  and  alkaline, 
581— of  birds,  581— carnivora,  581— of 
the  herbivora,  581 — of  serpents,  581. 

Valeryl,  473. 

Varnish,  428. 

Vegetable  acids,  374— alkalies,  493. 

Vegetable    albumen,    413 — caseine,  411, 


415,  418— elements,  418— fibrin,  415— 
growth,  582— life,  586— substances,  371 

Vegeto-alkalies,  493. 

Vegeto-animal  ferment,  597. 

Vegeto-animal  substances,  411. 

Veratria,  507,  519. 

Veratrine,  507. 

Veratrum  sabadilla,  507. 

Venous  blood,  595— fibrine,  567. 

Vinegar,  457. 

Vinous  fermentation,  597. 

Violine,  496. 

Viscous  fermentation,  598. 

Volatile  bases,  519— oils,  429,  434— oils 
formula  of,  436. 

Watch  work,  oil  for,  423. 

Water,  373,  374* — rain,  contains  ammo- 
nia, 583. 

Waves,  abating  influence  of  oil  on,  430. 

Wax,  446,  447,  592. 

Wheat,  413,  416. 

White  helebore,  507. 

Will  and  Varentrap's  process  for  nitro- 
gen, 374. 

Willow,  salycyl  or  salicin,  from  bark  of 
the,  384. 

Winter  strained  oil,  422. 

Wood,  409— distillation  of,  457. 

Wood  spirit,  395,  552. 

Wool,  dyeing  of,  420. 

Wort,  401,  409,  597. 

Xanthopicrine,  525. 
Xanthic  oxide,  582. 
Xylit,  559. 
Xylite,  559. 
Xylite  naptha,  560. 
Xylite  oil,  560. 

Yellow  wax,  447. 

Zedourine,  528. 
Zimome,  412. 

*  See    Inorganic  Chemistry. 


EMENDATIONS 

'ding  the  Isomeric  Acids  of  Phosphorus,  the  Atomic  Weight 
of  Silicon,  and  Composition  of  Silica. 

It  will  be  perceived  by  the  readers  of  that  portion  of  this  Com- 
pendium which  treats  of  "  acids  relatively  to  the  proportion  of  base 
required  for  saturation"(51Sl),  that  a  new  doctrine  has  been  ad- 
vanced on  that  subject.  Consistently  a  very  important  modification 
has  been  made  with  respect  to  the  three  previously  supposed  isome- 
ric  states  of  phosphoric  acid  (1153).  They  are  inferred  to  differ 
from  each  other  only  in  the  proportions  of  water,  or  other  base 
which  they  require  severally  for  their  saturation;  so  that  there  is  a 
monobasic,  a  bibasic,  and  tribasic  phosphoric  acid  (5184).  When  in 
the  state  heretofore  designated  as  free,  they  are  considered  as  con- 
stituting three  phosphates  of  water.  This  assumed  constitution  of 
these  isomeric  acids  has  been  represented  by  Dr.  Kane,  and  other 
respectable  chemists,  as  affording  strong  evidence  of  the  existence  of 
compound  radicals  in  certain  salts.  Hence  having,  in  arguing  against 
the  existence  of  such  radicals,  adverted  to  the  constitution  of  the  dif- 
ferent phosphates  of  water,*  I  deem  it  expedient  to  give,  in  the  lan- 
guage of  Dr.  Kane,t  an  account  of  the  acids  of  phosphorus  to  which 
reference  is  made,  and  of  their  habitudes  with  basic  water  and  other 
bases. 

"The  Phosphoric  acid  has  a  great  affinity  for  water,  combining  with  it  almost  ex- 
plosively. It  may  form  three  distinct  compounds,  phosphates  of  water,  the  constitu- 
tion of  which  is  as  follows:  — 

Monobasic  phosphate  of  water,          -        -         PO5  +    HO. 
Bibasic  phosphate  of  water,  -        -         PO  +  2HO. 

Tribasic  phosphate  of  water,  -         -        PO  +  3HO. 

This  relation  was  first  established  by  the  researches  of  Graham.  Phosphoric  acid 
combines  not  only  with  water  in  these  three  proportions,  but  each  of  them  is  a  type 
of  a  series  of  salts,  which  the  phosphoric  acid  is  capable  of  forming.  Thus,  there  is 
a  class  of  monobasic  phosphates,  another  class  of  bibasic  phosphates,  and  a  third,  which 
is  the  most  common,  of  tribasic  phosphates;  the  water  contained  in  the  phosphates  of 
water  being  replaced  to  a  greater  or  less  extent,  by  means  of  equivalent  proportions 
of  ammonia  or  metallic  oxides. 

A  solution  of  phosphoric  acid  in  water,  may  contain  any  one  of  the  three  phos- 
phates of  water  that  have  been  described,  and  when  neutralized  by  bases  may  hence 
produce  totally  different  salts.  The  properties  of  a  solution  of  phosphoric  acid  may, 
therefore,  be  totally  different  according  to  the  manner  in  which  it  had  been  prepared, 
and  hence  this  acid  was  at  one  time  ranked  as  a  remarkable  instance  of  isomerism  ; 
but  Graham  has  beautifully  shown,  that  the  difference  of  properties  is  only  the  result 
of  the  existence  of  the  different  states  of  combination  in  which  the  phosphoric  acid 
actually  exists.  It  will  consequently  be  necessary  to  study  separately  the  properties 
of  the  three  compounds  of  phosphoric  acid  with  water. 

iwbasic  Phosphate  of  Water.—  -A  solution  of  this  body  reacts  powerfully  acid,  it 
precipitates  albumen  (white  of  egg)  in  white  curds;  when  neutralized  by  a  • 

-alts  which  contain  but  on<;  atom  of  base,  their  formula  being  PO^  -\-  RO;  and 
a  soluble  salt  of  it  produces  in  solutions  of  silver,  a  white,  soft,  precipitate,  PO5  -f- 


effort  to  refute  the  arguments  in  favour  of  the  existen^o-^  ^mphide  salts 
of  a  compound  radical  like  cyanogen. 
t  Elements,  page  485. 


XX 

AgO.  This  is  the  least  stable  of  the  phosphates  of  water,  it  gradually  passes  into 
the  other  forms,  particularly  when  its  solution  is  boiled. 

Bibasic  Phosphate  of  Water. — This  form  of  the  acid  may  be  prepared  by  decompo- 
sing bibasic  phosphate  of  lead  by  sulphuretted  hydrogen.  Jt  is  characterized  by 
combining  always  with  two  equivalents  of  base,  forming  salts,  whose  formula  is  I'd* 
4-  2RO;  its  salts  give,  with  nitrate  of  silver,  a  white  precipitate,  PO*  -j-  2AgO, 
which  is  not  pasty  like  the  monobasic  phosphate.  The  salts  of  this  acid  may  contain 
only  one  equivalent  of  fixed  base,  the  other  being  water,  and  may  hence,  at  first 
sight,  appear  to  be  constituted  like  the  monobasic  salts  ;  the  basic  water  is,  how- 
ever, easily  known  to  be  present,  by  its  not  being  expelled  by  a  moderate  heat,  with 
the  water  of  crystallization,  but  requiring  a  temperature  approaching  to  ignition  for 
its  expulsion. 

Tribasic  Phosphate  of  Water. — This  is  the  form  of  phosphoric  acid  which  represents 
the  class  of  salts  most  generally  known ;  it  is  characterized  by  not  precipitating  al- 
bumen, and  by  combining  with  three  equivalents  of  base  when  fully  neutralized.  In 
the  majority  of  cases  of  the  three  equivalents  of  base,  one  is  water;  thus  the  com- 
mon phosphate  of  soda  is  a  tribasic  phosphate,  its  formula  being  (PO5  -}-  2NaO.HO) 
4-  24Aq;  when  moderately  heated,  or  even  by  long  exposure  to  dry  air,  it  loses  the 
24Aq,  but  it  requires  to  be  melted  at  a  red  heat,  in  order  to  drive  off  the  twenty-fifth 
atom  of  water;  and  if  this  be  done,  on  redissolving  the  fused  mass  in  water,  it  crys- 
tallizes in  a  totally  different  form,  and  is  found  to  have  been  changed  into  bibasic 
phosphate  of  soda,  the  formula  of  which  is  (PO  +  2NaO)  -f-  lOAq.  The  difference 
is  remarkably  shown  by  the  action  of  these  salts  on  a  solution  of  silver ;  common 
phosphate  of  soda  precipitates  nitrate  of  silver  of  a  canary  yellow,  and  the  solution 
becomes  acid  ;  one  equivalent  of  tribasic  phosphate  of  soda,  decomposing  three  equi- 
valents of  nitrate  of  silver,  producing  one  equivalent  of  tribasic  phosphate  of  silver, 
two  of  nitrate  of  soda,  and  one  of  nitrate  of  water;  this  last  being  liquid  nitric  acid, 
of  course  renders  the  liquor  acid.  The  reaction  may  be  simply  expressed 

PQ5  +  2NaO.HO  and  3  (NO  -J-  AgO) 
give  PO-  -f  3AgO  .  .  .  2(NO*  +  NaO)  and  NO3  4-  HO. 

If  on  the  other  hand,  bibasic  phosphate  of  soda  be  used,  the  liquor  remains  neutral, 
for  PO5  4-  2NaO  and  2(NO*  4-  AgO)  give  PO*  4-  2AgO  and  2(NO*  4-  JNaO). 

In  the  tribasic  phosphates,  it  frequently  occurs,  that  there  shall  be  but  one  equi- 
valent of  fixed  base,  the  other  two  being  water;  such  salts  have  frequently  an  acid 
reaction,  and  were  formerly  called  biphosphates.  Thus  one  tribasic  phosphate  of  soda 
is  PO3  4-  NaO.2HO;  the  biphosphate  of  ammonia  is  tribasic,  its  formula  being  PO' 
4-  NHO.  2HO. 

These  salts  of  phosphoric  acid  were  originally  designated  by  Graham,  metaphos- 
phates,  pyrophosphates,  and  common  phosphates." 

It  may  be  proper  to  add  that  the  opinion  of  Professor  Rose  re- 
specting the  identity  in  composition  of  the  different  kinds  of  phos- 
phuretted  hydrogen(1166),  of  which  one  only  is  spontaneously  in- 
flammable, has  been  confirmed.  According  to  analysis,  either  con- 
sists of  an  atom,  or  volume,  of  phosphorus  and  three  atoms,  or  six 
volumes,  of  hydrogen,  the  whole  aggregate  being  condensed  into 
four. 

Their  unlikeness, as  respects  spontaneous  inflammability,  is  ascribed 
to  the  presence  of  impurities  which  tend  either  to  promote  or  to  re- 
tard reaction  with  atmospheric  oxygen. 

•fltomic  Weight  of  Silicon  and  Composition  of  its  Oxide. 

Jn  this  Compendium  (1361),  the  equivalent  of  silicon  is  stated  to 
be  8,  and  that  taking  one  atom  of  oxj^gen  to  form  silicic  acid,  the 
equivalent  of  this  compound,  known  also  as  silex  or  silica,  is  16.  But 
latterly  it  has  been  inferred  that  the  equivalent  of  silicon  is  22.22 
And  that  to  form  silicic  acid  it  takes  3  atoms  of  oxygen  =  24. 

-~  -,* Consistently  the  equivalent  of  silicic  acid  is  46.22 


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